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Dec 16, 1994, 6:38:52 PM12/16/94

N M E A

NATIONAL MARINE ELECTRONICS ASSOCIATION

NMEA 0183

STANDARD FOR INTERFACING MARINE ELECTRONIC DEVICES

Version 2.00

January 1, 1992

This is an unauthorized copy - psst!
CONTENTS

0. PREFACE

1. INTRODUCTION

2. MANUFACTURER'S DOCUMENTATION

3. HARDWARE SPECIFICATION

4. DATA TRANSMISSION

5. DATA FORMAT PROTOCOL

6. DATA CONTENT

7. EXAMPLE SENTENCES

APPENDIX I - Sentences Not Recommended For New Designs

APPENDIX II - IMO List of Equipment and Notes

APPENDIX III - Manufacturer's Mnemonic Codes

APPENDIX IV - Glossary of Terms

Index
0. Preface......................................................... 01
Availability and Updates of the Standard........................ 02
1. Introduction.................................................... 03
1.1 Scope...................................................... 03
1.2 Intended Application and Limitations on Use................ 03
1.3 Definitions................................................ 03
1.3.1 General............................................. 03
1.3.2 TALKERs............................................. 03
1.3.3 LISTENERs........................................... 03
1.4 References................................................. 03
2. Manufacturer's Documentation.................................... 04
3. Hardware Specification.......................................... 05
3.1 Interconnection Wire....................................... 05
3.2 Conductor Definitions.......................................... 05
3.3 Electrical Connections/Shield Requirements................. 05
3.4 Connector.................................................. 05
3.5 Electrical Signal Characteristics.......................... 05
3.5.1 Signal State Definitions........................ 05
3.5.2 TALKER Drive Circuits............................... 06
3.5.3 LISTENER Receive Circuits........................... 06
3.5.4 Electrical Isolation................................ 07
3.5.5 Maximum Voltage on Bus.............................. 07
4. Data Transmission............................................... 07
5. Data Format Protocol............................................ 08
5.1 Characters................................................. 08
5.1.1 Reserved Characters................................. 08
5.1.2 Valid Characters.................................... 08
5.1.3 Undefined Character................................. 08
5.1.4 Character Symbols................................... 08
5.2 Fields..................................................... 08
5.2.1 Address Field....................................... 08
5.2.1.1 Approved Address Field....................... 09
5.2.1.2 Query Address Field.......................... 09
5.2.1.3 Proprietary Address Field.................... 09
5.2.2 Data Fields......................................... 09
5.2.2.1 Variable Length Field........................ 09
5.2.2.2 Data Field Types............................. 10
5.2.2.3 Null Fields.................................. 10
5.2.3 Checksum Field...................................... 10
5.3 Sentences.................................................. 10
5.3.1 Approved Sentences.................................. 11
5.3.1.1 Approved Sentence Structure.................. 12
5.3.2 Query Sentences..................................... 13
5.3.2.1 Reply to Query Sentence...................... 13
5.3.3 Proprietary Sentences............................... 13
5.3.4 Valid Sentences..................................... 14
5.3.5 Sentence Transmission Timing........................ 14
5.3.6 Additions to Approved Sentences..................... 14
6. Data Content.................................................... 15
TABLE 1 - RESERVED CHARACTERS.................................. 15
TABLE 2 - VALID CHARACTERS..................................... 15
TABLE 3 - CHARACTER SYMBOL TABLE............................... 16
TABLE 4 - TALKER IDENTIFIER MNEMONICS.......................... 17
TABLE 5 - APPROVED SENTENCE FORMATTERS......................... 18
TABLE 6 - FIELD TYPE SUMMARY................................... 20
6.3 Approved Sentences......................................... 22
7. Applications.................................................... 39
7.1 Example Sentences.......................................... 39
7.2 Receiver Diagrams.......................................... 42
0. Preface

NMEA Interface Standards are intended to serve the public
interest by facilitating interconnection and interchangeability
of eqipment, minimizing misunderstanding and confusion between
manufacturers, and assisting purchasers in selecting compatiblr
equipment.

Standards are adopted by NMEA without regard to whether or not
their adoption may involve patents on articles, materials or
processes. By such action, NMEA does not assume any liability to
any patent owner, nor does it assume any obligation whatever to
parties adopting these Standards.

This Standard defines electrical signal requirements, data trans-
mission protocol and timing, and specific sentence formats for a
4800 baud serial data bus. Each bus may have only a single TALK-
ER but may have multiple LISTENERS.

Because of differences in baud rate and other transmission param-
eters, NMEA 0183 data is not directly compatible with NMEA 0180
or NMEA 0182 Standards.

Equipment that is specified by IMO to meet the SOLAS regulations
is governed by the requirements of IEC doc. TC80/WG6.
The IEC Standard is aligned closely with the NMEA 0183 Standard.
Where possible, differences between the two documents, and sec-
tions that pertain specifically to IEC requirements, are indi-
cated herein by the symbol "*" in the margin.

Information on the availability of these standards will be found
on the following page.

Page 01
Availability and Updates of the Standard

This standard may be modified by action of the NMEA Interface
Standards Comittee as the need arises.

Updates to this Standard are published periodically in:

Marine Electronics - The Official Journal of the NMEA
330 W. Canton Avenue
Winter Park, FL 32789
U.S.A.

For additional or updated copies of this standard, contact:

Robert Sassaman Telephone: (205) 473-1793
NMEA Executive Director FAX: (205) 473-1669
P.O. Box 50040
Mobile, AL 36605
U.S,A,

For copies of IEC STandard doc. TC80/WG6, contact:
International Electrotechnical Commission
3, rue de Varembe
P.O. Box 131
1211 Geneva 20
SWITZERLAND

Or the appropriate National Standards Institution

For technical information, contact:

Chairman, NMEA 0183 Committee for Interfacing Marine Elec-
tronic Navigational Devices:

Frank Cassidy Telephone: (508) 563-7151
Datamarine International, Inc. FAX: (508) 564-4707
53 Portside Drive
Pocasset, MA 02559
U.S.A.

Secretary, I.E.C. Technical Committee 80/Working Group 6:

Michael P. Fox Telephone: 071-587-1245
Secretary General, C.I.R.M. FAX: 071-587-1436
South Bank House
Black Prince Road
London SE1 7SJ
ENGLAND

Page 02
1. Introduction

1.1 Scope

This standard is developed to permit ready and satisfactory data
communication between electronic marine instruments, navigation
equipment and communications equipment when interconnected via an
appropriate system.

1.2 Intended Application and Limitations on Use

This standard is intended to support one-way serial data trans-
mission from a single TALKER to one or more LISTENERs. This is
data in printable ASCII form and may include information such as
position, speed, depth, frequeny allocation, etc. Typical mes-
sages might be 20 to 80 characters in length and generally re-
quire transmission no more often than once per second.

The electrical definitions in this standard are not intended to
accommodate high-bandwidth applications such as radar or video
imagery, or intensive databased or file transfer applications.

Since there is no provision for garanteed delivery of messages
and only limited error checking capability, this standard should
be used with caution in critical applications.

1.3 Definitions

1.3.1 General

Common terms are defined in Apendix IV, Glossary, of this Stand-
ard. Where there is a conflict terms shall be interpreted wher-
ever possible in accordance with the references in Section 1.4.

1.3.2 TALKERs

A TALKER is any device which sends data to other devices within
this specification. The type of TALKER is identified by a 2-
character mnemonic as listed in Section 6.2 (Table 4).

1.3.3 LISTENERs

A LISTENER is any device which receives data from another device
within this specification.

1.4 References

1.4.1 American National Standards Institute:
A. ANSI X 3.15 1976 ANSI Character Structure and
Character Parity Sense for Serial-by-Bit Communication
B. ANSI X 3.16 1976 ANSI for Bit Sequencing of the ANS
Code or Information Interchange in Serial-By-Bit Data
Transmission.
C. ANSI X 3.14 1977 ANSI Code for Information Interchange

Page 03
1.4.2 Electronic Industries Association Standards:
A. EIA-422-A December 1978 (CCITT X.27/V.11)

1.4.3 International Electrotechnical Commission:
A. IEC 945, Marine Navigational Equipment - General
Requirements
B. IEC doc. TC80/WG6

1.4.4 American Practical Navigator, Defence Mapping Agency Hydro
graphic/Topographic Center, Publication No. 9, DMA Stock
No. NVPUB9V1, Volumes I and II

1.4.5 Interface Control Document, Navstar GPS Space
Segment/Navigation User Interface. Rockwell International
Corporation Document No. ICD-GPS-200 Revision B (November
30, 1987).

2. Manufacturer's Documentation

Operator's manuals or other appropriate literature provided for
equipment that is intended to meet the requirements of this
standard shall contain the following information:

1. Identification of the A and B signal lines.

2. The output drive capability as a TALKER.

3. A list of approved sentences, noting unused fields, Pro-
prietary sentences transmitted as a TALKER, and transmis-
sion interval for each sentence.

4. The load requirements as a LISTENER.

5. A list of sentences and associated data fields that are
required as a LISTENER.

6. The current software and hardware revision if this is
relevant to the interface.

7. An electrical description or schematic of the
LISTENER/TALKER input/output circuits citing actual
components and devices used, including connector type and
part number.

8. The Version No. and Date of Update of the standard for
which compliance is assured.

Page 04
3. Hardware Specification

One TALKER and multiple LISTENERS may be connected in parallel
over an interconnecting wire. The number of LISTENERS depends on
the output capability and input drive requirements of individual
devices.

3.1 Interconnecting Wire

Interconnection between devices may be by means of a two-conduc-
tor, shielded, twisted-pair wire.

3.2 Conductor Definitions

The conductors referred to in this standard are the signal lines
"A" and "B", and shield.

3.3 Electrical Connections/Shield Requirements

All signal line "A" connections are connected in parallel with
all device "A" connections and all signal line "B" connections
are connected in parallel with all device "B" connections. The
shield should be connected to the TALKER chassis and should not
be connected at any LISTENER. However, the shield should be
continuos (unbroken) between all listeners.

* A continuous DC path between TALKER and LISTENER signal grounds
* is required as provided for by EIA-422 if EIA-422 receivers are
* used in IEC applications. This path is generally part of the
* equipment safety (or chassis) grounding system.

3.4 Connector

No standard connector is specified. Wherever possible readily
available commercial connectors should be used. Manufacturers
shall provide means for user identification of the connections
used.

3.5 Electrical Signal Characteristics

This section describes the electrical characteristics of trans-
mitters and receivers.

3.5.1 Signal State Definitions

The idle, marking, logical "1", OFF or stop bit state is defined
by a negative voltage on line "A" with respect to line "B".

The active, spacing, logical"0", ON or start bit state is de-
fined by a positive voltage on line "A" with respect to line "B".

Note that the above "A" with respect to "B" levels are inverted
from the voltage input/output requirements of standard UARTs and
that many line drivers and receivers provide a logical inversion.

Page 05
3.5.2 TALKER Drive Circuits

No provision is made for more than a single TALKER to be connect-
ed to the bus. The drive circuit used to provide the signal "A"
and the return "B" shall meet, at a minimum, the requirements of
EIA-422-A (December 1978).

3.5.3 LISTENER Receive Circuits

Multiple LISTENERs may be connected to a single TALKER. The
LISTENER receive circuit shall consist of an optoisolator and
should have protective circuits to limit current, reverse bias
and power dissipation at the optodiode as shown in Figure 1.
Reference is made to example circuits in Section 7.0 of this
Standard.

The receive circuit shall be designed for operation with a mini-
mum differential input voltage of 2.0 volts and shall not take
more than 2.0 mA from the line at that voltage.

For reasons of compatibility with equipment designed to earlier
versions of this standard, it is noted that the 'idle, marking,
logical "1", OFF or stop bit state' had previously< been defined
to be in the range -15 to +0.5 volts. The active, spacing,
logical "0", ON or start bit state' was defined to be in the
range +4.0 to +15 volts while sourcing not less than 15mA.

* In places of this optoisolator receive circuit the IEC alternately
* allows the use of a differential-receiver that meets the require-
* ments of EIA-422-A (December 1978). This configuration is not
* compatible with equipment designed to meet previous versions of
* this standard that made use of single-ended unbalanced drive
* circuits.

$ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $
- OPTO-ISOLATOR
| | +--------+ - - - - - - - -
| | | | $
+-----------O---| |-------+ +------
| | | | |
| A| | | | | | | | L $
| |PROTECT-| | | I
| | | | | _|_ | S
| | | | \ | / / | T $
| | | | IVE | \|/ \|\ |/ E
| | | --- \| | N
| | | | | | | - |\| | E
| | | | -\ R $
| | | | | | |
| |CIRCUITS| | | | | #
| B| | | | | | 1 $
| | | | |
| +--------O---| |-------+ +------
| | | | | | $
| | | | +--------+ - - - - - - - -
| | -
| | $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $
$ $ $ $ $ $ | |
| |
| |
$ $ | | $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $
|\ - | | - OPTO-ISOLATOR
| \ | |/ | | | +--------+ - - - - - - - -
$ | \ / | | | | $
---| -----O--------------O---| |-------+ +------
| / | | | |
$ | / A| | | A| | | | | | | | L $
|/O-+ | |PROTECT-| | | I
| | | | | | | | _|_ | S
$ | | | | | \ | / / | T $
EIA-422 | | | | | | | IVE | \|/ \|\ |/ E
| | | | --- \| | N
| | | | | | | | | | - |\| | E
| / | | | -\ R $
$ | | | / | | | | | |
| / |CIRCUITS| | | | | #
| B| |/ B| | | | | | 2 $
$ | / | | | |
+----O--------------O---| |-------+ +------
| | | | | | $
$ +----O | | +--------+ - - - - - - - -
| | |SHIELDS -
--- - $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $
$ \_/ $
TALKER

$ $ $ $ $ $
(FIGURE 1)

Page 06
3.5.4 Electrical Isolation

Within a LISTENER there shall be no direct electrical connection
between the signal line, "A", return line, "B", or shield and
ship's ground or power. Isolation from ships ground is required.

3.5.5 Maximum Voltage on Bus

The maximum applied voltage between signal lines "A" and "B" and
between either line and Ground will be in accordance with the
EIA-422 specification.

For protection against miswiring and for use with earlier TALKER
designes, all receive curcuit devices should be capable of with-
standing 15 volts between signal lines "A" and "B" and between
either line and ground for an indefinite period.

4. Data Transmission

Data is transmitted in serial asynchronous form in accordance
with ANSI standards (reference paragraph 1.4.1). The first bit
is a start bit and is followed by data bits, least-significant-
bit first as illustrared by Figure 2. The following parameters
are used:

Baud rate 4800
Data bits 8 (d7 = 0)
Parity None
Stop bits One

+----+----+----+----+----+----+----+----+----+
| | | | | | | | | |
| | D0 | D1 | D2 | D3 | D4 | D5 | D6 | D7 | |
----+ +----+----+----+----+----+----+----+----+----+--

(FIGURE 2)

Page 07
5. Data Format Protocol

5.1 Characters

All transmitted data shall be interpreted as ASCII characters.
The most significant bit of the 8-bit character shall always be
transmitted as zero (d7 = 0).

5.1.1 Reserved Characters

The reserved character set consist of those ASCII characters
shown in Section 6.1 (Table 1). These characters are used for
specific formatting purposes, such as sentence and field delimit-
ing, and may not be used in data fields.

5.1.2 Valid Characters

The valid character set consist of all printable ASCII charac-
ters (HEX 20 to HEX 7E) except those defined as reserved charc-
ters. Section 6.1 (Table 2) lists the valid character set.

5.1.3 Undefined Characters

ASCII values not specified as either "reserved characters" or
"valid characters" are excluded and may not be transmitted at any
time.

5.1.4 Character Symbols
When individual characters are used in this standard to define
units of measure, indicate the type of data field, type of sen-
tence, etc. they will be interpreted according to the character
symbol table in Section 6.1 (Table 3).

5.2 Fields

A Field consists of a string of valid characters, or no charac-
ters (null field), located between two appropriate delimiter
characters.

5.2.1 Address Field

An address field is the first field in a sentence and follows the
"$" delimiter, it serves to define the sentence. Characters
within the address field are limited to digits and upper case
letters. The address field may not be a null field. Only sen-
tences with the following three types of address fileds may be
transmitted:

Page 08
5.2.1.1 Approved Address Field

Approved address fields consist of five characters defined by
this standard. The first two characters are the TALKER Identifi-
er, listed in Section 6.2 (Table 4). The next three characters
form the Sentence Formatter used to define the format and the
type of data. Section 6.2 (Table 5) and Appendix I list approved
Sentence Formatters.

5.2.1.2 Query Address Field

The query address consists of five characters and is used for the
purpose of requesting transmission of a specific sentence on a
separate bus from an identified TALKER.

The first two characters are the TALKER Identifier of the device
requesting data, the next two characters are the TALKER Identifi-
er of the device being addressed and the final character is the
query character "Q".

5.2.1.3 Proprietary Address Field

The proprietary address field consists of the proprietary charc-
ter "P" followed by a three-character Manufacturer's Mnemonic
Code, used to identify the TALKER issuing a proprietary sentence,
and any additional characters as required. A list of valid Manu-
facturer's Mnemonic Codes is contained in Appendix III.

5.2.2 Data Fields

Data Fields in approved sentences follow a "," delimiter and con-
tain valid characters in accordance with the formats illustrated
in Section 6.2 (Table 6). Data fields in proprietary sentences
contain only valid characters but are not defined by this stand-
ard.

Because of the presence of variable data fields and null fields,
specific data fileds may only be located within a sentence by ob-
serving the field delimiters ",". Therefore it is essential for
the LISTENER to locate fields by counting delimiters rather than
counting total numbers of characters received from the start of
the sentence.

5.2.2.1 Variable Length Fields

Although some data fields are defined to have fixed length, many
are of variable lenght in order to allow devices to convey infor-
mation and to provide data with more or less precission, according
to the capability or requirements of a particular device.

Variable length fields may be alpha-numeric or numeric fileds.
Variable numeric fields may contain a decimal point and may con-
tain leading or trailing "zeros".

Page 09
5.2.2.2 Data Field Types

Data fields may be alpha, numeric, alphanumeric, variable length,
fixed length, fixed/variable (with a portion fixed in length
while the remainder varies). Some fields are constant, with
their value dictated by a specific sentence definition. The al-
lowable field types are summarized in section 6.2 (Table 6),
Field Type Summary.

5.2.2.3 Null Fields

A null field is a field of length zero, i.e. no character are
transmitted in the field. Null fields shall be used when the
value is unreliable or not available.

For example, if heading information were not available, sending
data of "000" is misleading because a user cannot sidtinguish
between "000" meaning no data and a legitimate heading of "000".
However, a null field, with no characters at all, clearly indi-
cates that no data is being transmitted.

Null fileds with their delimiters can have the following
appearance depending on where they are located in the sentence:

",," ",*" ",<CR><LF>"

The ASCII NULL character (HEX 00) shall not be used as the null
field.

5.2.3 Checksum Field

A checksume filed may optionally be transmitted in any sentence.
However some approved sentences specifically require the checksum
field. The checksum field is the last field in a sentence and
follows the checksum delimiter character "*".

The checksum is the 8-bit exclusive OR (no start or stop bits) of
all characters in the sentence, including "," delimiters, between
but not including the "$" and the "*" delimiters.

The hexadecimal value of the most significant and least signifi-
cant 4 bits of the result are converted to two ASCII characters
(0-9, A-F) for transmission. The most significant character is
transmitted first.

5.3 Sentences

This section describes the general structure of sentences. De-
tails of specific sentences may specify restrictions beyond the
general limitations given in this part of the standard. Such re-
strictions may include defining some fields as fixed length, nu-
meric or text only, required to be non-null, transmitted with a
certain frequency, etc.

Page 10
The maximum number of characters in a sentence shall be 82, con-
sisting of a maximum of79 characters between the starting delim-
iter "$" and the terminating <CR><LF>.

The minimum number of fields in a sentence is one (1). The first
field shall be an address field containing the identity of the
TALKER and the sentence formatter which specifies the number of
data fields in the sentence, the type of data they contain and
the order in which the data fields are transmitted. The remain-
ing portion of the sentence may contain zero or multiple data
fields.

The maximum number of fields allowed in a single sentence is lim-
itetd only by the maximum sentence length of 82 characters. Null
fields may be presented in the sentence and shall always be used if
data for that field is unavailable.

All sentences bebin with the sentence start delimiter character
"$" and end with the sentence termination delimiter <CR><LF>.

5.3.1 Approved Sentences

Approved sentences are those designed for general use and de-
tailed in this Standard. Approved sentences are listed in Sec-
tion 6.3 and Appendix I of the current version of the Standard.
Preferred sentences are contain in Section 6.3 and these sen-
tences should be used wherever possible. Appendix I contains
sentences that may be phased-out of use, are not recommend for
new designes, but may be met in practise.

An approved sentence contains, in the order shown, the following
elements:

"$" HEX 24 - Start of sentence
<address field> TALKER identifier and sentence formatter
[","<data field>] Zero or more data fields
.
.
.
[","<data field>]
["*"<checksum field>] Optional checksum field
<CR><LF> Hex 0D 0A - End of sentence

Page 11
5.3.1.1 Approved Sentence Structure

The following provides a summary explanation of the approved
sentence structure: $aaccc,c--c*hh<CR><LF>

ASCII HEX DESCRIPTION

"$" 24 Start of Sentence.

aaccc Address Field. Alphanumeric characters
identifying type of TALKER, and Sentence
Formatter. The first two characters iden-
tify the TALKER. The last three are the
Sentence Formatter mnemonic code identify-
ing the data type and the string formt of
the successive Fields. Mnemonics will be
used as far as posible to facilitate
readouts by users.

"," 2C Field delmiter. Starts each Field except
Address and Checksum fields. If it is
followed by a null field, it is all that
remainsto indicate no data in field.

c--c Data sentence block. Follows Address
field and is a series of data fields con-
taining all of the data to be transmitted.
Data field sequences is fixed and identified
by 3rd and subsequent characters of the
address field (the "Sentence Formatter").
Data fields may be of variable length and
are preceded by delimiters ",".

"*" 2A Optional Checksum Delimiter. Follows
last Data field of the sentence. It indi-
cates that the following two alpha-numeric
characters show the HEX value of the CHECK-
SUM.

hh Optional Checksum Field. The absolute
value calculatedby exclusive-OR'ing the 8
data bits (no start bits or stop bits) of
each character in the Sentence, between,
but excluding "$" and "*". The hexadecimal
value of the most significant and least
significant 4 bits of the result are con-
verted to two ASCII characters (0-9, A-F)
for transmission. The most significant
character is transmitted first. The
"CHECKSUM" field is optional, except when
indicated as mandatory.

<CR><LF> 0D 0A Terminates Sentence.

Page 12
5.3.2 Query Sentences

Query sentences are intended to request Approved sentences to be
transmittetd from a TALKER on a seperate bus in a form of two way
communication.

The approved Query sentence contains, in the order shown, the
following elements:

"$" HEX 24 - Start of sentence
<aa> TALKER Identifier or requester
<aa> TALKER Identifier for device from which
data is being requested
"Q" Query character identifies Query address
"," Data field delimiter
<ccc> Approved sentence formatter of data
being requested
["*"<checksum field>] Optional checksum field
<CR><LF> HEX 0D 0A - End of sentence

5.3.2.1 Reply to Query Sentence

The reply on a seperate bus to a Query sentence is the Approved
sentence that was requested. The use of Query sentences requires
cooperation between the devices that are interconnected, a reply
to a Query sentence is not mandatory and there is no specified
time delay between the receipt of a query and the reply.

5.3.3 Proprietary Sentences

Proprietary sentences provide a means for manufacturers to use
the sentence structure definitions of this standard to transfer
data which does not fall within the scope of approved sentences.
This will generally be for one of the following reasons:

-Data is intended for another device from the same manu-
facturer, is device specific, and not in a form or of a
type of interest to the general user;

-Data is being used for test purposes prior to the adop-
tion of approved sentences;

-Data is not of a type and general usefulness which
merits the creation of an approved sentence.

A proprietary sentence contains, in the order shown, the follow-
ing elements:

"$" Hex 24 - Start of sentence
"P" Hex 50 - Proprietary sentence ID
<aaa> Manufacturer's Mnemonic code
[<valid characters, manufacturer's data>]
["*"<checksum field>] Optional checksum field
<CR><LF> Hex 0D 0A - End of sentence

Page 13
Beyond limiting overall sentence length are requiring the use of
only valid characters, details of proprietary data fields will
not be included in this standard and need not be submitted for
approval. However it is required that such sentences be pub-
lished in the manufacturer's manuals for reference.

5.3.4 Valid Sentences

Approved sentences, Query sentences and Proprietary sentences are
the only valid sentences. Sentences of any other form are non-
valid and shall not be transmitted on the bus.

5.3.5 Sentences Transmission Timing

Frequency of sentence transmission when specified shall be in
accordance with the approved sentence definitions (Section 6.3 and
Appendix I): When not specified, the rate should be consistent
with the basic measurement or calculation cycle but generally
not more frequently than once per second.

It is desirable that sentences be transmitted with minimum inter-
character spacing, preferably as a near continuous burst, but under
no circumstance shall the time to complete the transmission of a
sentence be greater than 1 second.

5.3.6 Additions to Approved Sentences

In order to allow for improvements or additions, future revisions
of this Standard may modify existing sentences by adding new data
fields after the last data field but before the optional checksum
delimiter character "*" and checksum field. LISTENERs should
determine the end of the sentence by recognition of "<CR><LF>"
and "*" rather than by counting field delimiters. The checksum
value should be computed on all received characters between, but
not including, "$" and "*" whether or not the LISTENER recognizes
all fields.

Page 14
6. Data Content

6.1 Character Definitions

TABLE 1 - RESERVED CHARACTERS

HEX DEC
<CR> 0D 13 Carriage return } End of sent-
<LF> 0A 10 Line feed } tence delimiter
$ 24 36 Start of sentence delimiter
* 2A 42 Checksum field delimiter
, 2C 44 Field delimiter
! 21 33 Reserved for future use
\ 5C 92 Reserved for future use
^ 5E 94 Reserved for future use
~ 7E 126 Reserved for future use

TABLE 2 - VALID CHARACTERS

HEX DEC HEX DEC HEX DEC
Space 20 32 @ 40 64 ` 60 96
Reserved A 41 65 a 61 97
" 22 34 B 42 66 b 62 98
# 23 35 C 43 67 c 63 99
Reserved D 44 68 d 64 100
% 25 37 E 45 69 e 65 101
& 26 38 F 46 70 f 66 102
' 27 39 G 47 71 g 67 103
( 28 40 H 48 72 h 68 104
) 29 41 I 49 73 i 69 105
Reserved J 4A 74 j 6A 106
+ 2B 43 K 4B 75 k 6B 107
Reserved L 4C 76 l 6C 108
- 2D 45 M 4D 77 m 6D 109
. 2E 46 N 4E 78 n 6E 110
/ 2F 47 O 4F 79 o 6F 111
0 30 48 P 50 80 p 70 112
1 31 49 Q 51 81 q 71 113
2 32 50 R 52 82 r 72 114
3 33 51 S 53 83 s 73 115
4 34 52 T 54 84 t 74 116
5 35 53 U 55 85 u 75 117
6 36 54 V 56 86 v 76 118
7 37 55 W 57 87 w 77 119
8 38 56 X 58 88 x 78 120
9 39 57 Y 59 89 y 79 121
: 3A 58 Z 5A 90 z 7A 122
; 3B 59 [ 5B 91 { 7B 123
< 3C 60 Reserved | 7C 124
= 3D 61 ] 5D 93 } 7D 125
> 3E 62 Reserved Reserved
? 3F 63 _ 5F 95 --------

Page 15
6.1 Character Definitions
(continued)

TABLE 3 - CHARACTER SYMBOL TABLE

A Status symbol; Yes; Data Valid; Warning Flag Clear; Auto
a Alphabet character variable A through Z or a through z
B Bars (pressure, 1000 Mb equal 1 Std. Atm.); Bottom
C Celsius (Degrees); Course-up
c Valid characters; Calculating
D Degrees (of Arc)
E Error; East; Engine
F Fathoms
f Feet
G Great Circle; Green
g Good
H Compass Heading; Head-up; Hertz; Humidity
h Hours; HEX number
I Inches
J Input operation completed
K Kilometers; Km/hour
k Kilograms
L Left; Local; Lost Target
l Latitude; Liters; Liters/second
M Meters; Meters/second; Magnetic; Manual; Cubic Meters
m Minutes; message
N Nautical miles; Knots; North; North-up; Newtons
n Numeral; address
P Purple; Proprietary (only when following "$"); Position
sensor; Percent
Q Query; Target-Being-Acquired
R Right; Rhumb line; Red; Relative; Reference; RADAR Tracking
S South; Statue miles; Statute miles/hour; Shaft
s Seconds
T Time difference; True; Track; Tracked-Target
t Test
U Dead Reckoning Estimate
u Sign, if minus "-" (HEX 2D)
V Data invalid; No; Warning Flag Set; Manual
W West; Water
x Numeric Character variable
y Longitude
Z Time

Page 16
6.2 Field Definitions

TABLE 4 - TALKER IDENTIFIER MNEMONICS
(Address Characters 1 and 2)

TALKER DEVICE IDENTIFIER

AUTOPILOT: General *AG
Magnetic AP
COMMUNICATIONS: Digital Selective Calling (DSC) *CD
Satellite *CS
Radio-Telephone (MF/HF) *CT
Radio-Telephone (VHF) *CV
Scanning Receiver *CX
DECCA Navigation DE
Direction Finder *DF
Electronic Chart Display & Information System (ECDIS) EC
Emergancy Position Indicating Beacon (EPIRB) *EP
Engineroom Monitoring Systems ER
Global Positioning System (GPS) GP
HEADING SENSORS: Compass, Magnetic *HC
Gyro, North Seeking *HE
Gyro, Non-North Seeking HN
Integrated Instrumentation II
Integrated Navigation IN
LORAN: Loran-A LA
Loran-C LC
OMEGA Navigation System OM
Proprietary Code P
Radar and/or ARPA *RA
Sounder, depth *SD
Electronic positioning system, other/general TR
Sounder, scanning SS
Turn Rate Indicator *TI
TRANSIT Navigation System TR
VELOCITY SENSORS: Doppler, other/general *VD
Speed Log, Water, Magnetic VM
Speed Log, Water, Mechanical VW
TRANSDUCER YX
TIMEKEEPERS, TIME/DATE: Atomic Clock ZA
Chronometer ZC
Quartz ZQ
Radio Update, WWV or WWVH ZV
Weather Instruments WI

*
Designated by I.E.C. for use with I.M.O. marine electronic
devices. This is the minimum requirement for equipment that is
specified by I.M.O. to meet S.O.L.A.S. regulations.

Page 17
6.2 Field Definitions
(continued)

TABLE 5 - APPROVED SENTENCE FORMATTERS

AAM - Waypoint Arrival Alarm............................... 22
ALM - GPS Almanac Data..................................... 22
APB - Autopilot Sentence "B"............................... 23
*ASD - Autopilot System Data................................ 23
BEC - Bearing & Distance to Waypoint, Dead Reckoning....... 23
BOD - Bearing, Origin to Destination....................... 24
BWC - Bearing & Distance to Waypoint, Great Circle......... 24
BWR - Bearing & Distance to Waypoint, Rhumb Line........... 24
BWW - Bearing, Waypoint to Waypoint........................ 24
DBT - Depth Below Transducer............................... 24
DCN - Decca Position....................................... 25
*DPT - Depth................................................ 25
*FSI - Frequency Set Information............................ 25
GGA - Global Positioning System Fix Data................... 26
GLC - Geographic Position, Loran-C......................... 26
GLL - Geographic Position, Latitude/Longitude.............. 27
GSA - GPS DOP and Active Satellites........................ 27
GSV - GPS Satellites in View............................... 27
GXA - TRANSIT Position..................................... 28
*HDG - Heading, Deviation & Variation....................... 28
*HDT - Heading, True........................................ 28
HSC - Heading Steering Command............................. 28
LCD - Loran-C Signal Data.................................. 29
MTW - Water Temperature.................................... 29
*MWV - Wind Speed and Angle................................. 29
OLN - Omega Lane Numbers................................... 29
*OSD - Own Ship Data........................................ 30
RMA - Recommend Minimum Specific Loran-C Data.............. 30
RMB - Recommend Minimum Navigation Information............. 31
RMC - Recommend Minimum Specific GPS/TRANSIT Data.......... 31
*ROT - Rate of Turn......................................... 32
*RPM - Revolutions.......................................... 32
*RSA - Rudder Sensor Angle.................................. 32
*RSD - RADAR System Data.................................... 32
RTE - Routes............................................... 33
*SFI - Scanning Frequency Information....................... 33
STN - Multiple Data ID..................................... 34
TRF - TRANSIT Fix Data..................................... 34
*TTM - Tracked Target Message............................... 35
*VBW - Dual Ground/Water Speed.............................. 35
VDR - Set and Drift........................................ 35
VHW - Water Speed and Heading.............................. 35
VLW - Distance Traveled through the Water.................. 36

Page 18
6.2 Field Definitions
(continued)

VPW - Speed, Measured Parallel to Wind..................... 36
VTG - Track Made Good and Ground Speed..................... 36
WCV - Waypoint Closure Velocity............................ 36
WNC - Distance, Waypoint to Waypoint....................... 36
WPL - Waypoint Loacation................................... 36
XDR - Transducer Measurements.............................. 37
XTE - Cross-Track Error, Measured.......................... 37
XTR - Cross-Track Error, Dead Reckoning.................... 38
ZDA - Time & Date.......................................... 38
ZFO - UTC & Time from Origin Waypoint...................... 38
ZTG - UTC & Time to Destination Waypoint................... 38

Page 19
6.2 Field Definitions
(continued)

TABLE 6 - FIELD TYPE SUMMARY

Field Type Symbol Definition

Special Format Fields:

Status A Single character field:
A = Yes, Data Valid, Warning Flag Clear
V = No, Data Invalid, Warning Flag Set

Latitude llll.ll Fixed/Variable length field:
degreed|minutes.decimal - 2 fixed digits
of degrees, 2 fixed digits of minutes
and a variable number of digits for
decimal-fraction of minutes. Leading
zeros always included for degrees and
minutes to maintain fixed length. The
decimal point and associated decimal-
fraction are optional if full resolution
is not required.

Longitude yyyyy.yy Fixed/Variable length field:
degreed|minutes.decimal - 3 fixed digits
of degrees, 2 fixed digits of minutes
and a variable number of digits for
decimal-fraction of minutes. Leading
zeros always included for degrees and
minutes to maintain fixed length. The
decimal point and associated decimal-
fraction are optional if full resolution
is not required.

Time hhmmss.ss Fixed/Variable length field:
hours|minutes|seconds.decimal - 2 fixed
digits of hours, 2 fixed digits of
minutes, 2 fixed digits of seconds and a
variable number of digits for decimal-
fraction of seconds. Leading zeros
always included for hours, minutes and
seconds to maintain fixed length. The
decimal point and associated decimal-
fraction are optional if full resolution
is not required.

Page 20
6.2 Field Definitions
(continued)

TABLE 6 - FIELD TYPE SUMMARY
(continued)

Field Type Symbol Definition

Defined field Some fileds are specified to contain
pre-defined constants, most often alpha
characters. Such a field is indicated
in this standard by the presence of one
or more valid characters. Excluded from
the list of allowable characters are the
following which are used to indicate
field types within this standard:
"A", "a", "c", "hh", "hhmmss.ss",
"llll.ll", "x", "yyyyy.yy"

Numeric Value Fields:
Variable numbers x.x Variable length integer or floating
numeric field. optional leading and
trailing zeros. The decimal point and
associated decimal-fraction are optional
if full resolution is not required.
(example: 73.10 = 73.1 = 073.1 = 73)

Fixed HEX field hh__ Fixed length HEX numbers only, MSB
on the left

Information Fields:
Variable text c--c Variable length valid character field.

Fixed alpha field aa__ Fixed length field of upper-case or
lower case alpha characters

Fixed number field xx__ Fixed length field of numeric characters

Fixed text field cc__ Fixed length field of valid characters

NOTES:

1. Spaces may only be used in variable text fields.

2. A negative sign "-" (HEX 2D) is the first character in a Filed if
the value is negative. The sign is omitted if value is positive.

3. Units of measure fields are appropriate characters from the Symbol
Table (table 3) unless a specific unit of measure is indicated.

Page 21
6.3 Approved Sentences

General format of printed sentence information:

{mnemonic} - {name}
{definition paragraph}

$--{sentence}
| |
| +-{field descriptions}
+-------Start of sentence and Talker ID

*
Designated by I.E.C. for use with I.M.O. marine electronic
devices. This is the minimum requirement for equipment that is
specified by I.M.O. to meet S.O.L.A.S. regulations.

AAM - Waypoint Arrival Alarm

Status of arrival (entering the arrival circle, or passing the
perpendicular of the course line) at waypoint c--c.

$--AAM,A,A,x.x,N,c--c*hh<CR><LF>
| | | | |
| | | | +---------------Waypoint ID
| | | +------------------Units of radius, nautical miles
| | +---------------------Arrival circle radius
| +------------------------Status: A = perpendicular passed at waypoint
+--------------------------Status: A = arrival circled entered

ALM - GPS Almanac Data

Contains GPS week number, satellite health and the complete almanac
data for one satellite. Multiple messages may be transmitted, one
for each satellite in the GPS constellation, up to maximum of 32
messages.

$--ALM,x.x,x.x,xx,x.x,hh,hhhh,...
| | | | | |
| | | | | +-------e, eccentricity [3]
| | | | +-----------SV health, bits 17-24 of each almanac page [2]
| | | +--------------GPS week number [1]
| | +------------------Satellite PRN number, 01 to 32
| +---------------------Message number
+-------------------------Total number of messages

hh,hhhh,hhhh,hhhhhh,hhhhhh,...
| | | | |
| | | | +--------Omega, argument of perigee [3]
| | | +---------------SQRT(A), root of semi-major axis [3]
| | +---------------------OMEGADOT, rate of right ascension [3]
| +--------------------------(sigma) index i, inclination angle [3]
+------------------------------t index OA, almanac reference time [3]

hhhhhh,hhhhhh,hhh,hhh*hh<CR><LF>
| | | |
| | | +-----------a index f1, clock parameter [3]
| | +---------------a index f0, clock parameter [3]
| +---------------------M index O , mean anomaly [3]
+----------------------------(OMEGA) index O, longitude of ascension node[3]

Page 22
Notes:

[1] Variable lengh integer, 4-digits maximum. Converted from (10) most
significant binary bits of Subframe 1, Word 3. Reference Table 20-I,
ICD-GPS-200, Rev. B.

[2] Reference paragraph 20.3.3.5.1.3, Table 20-VII and Table 20-VIII, ICD-
GPS-200, Rev. B.

[3] Reference Table 20-VI, ICD-GPS-200, Rev. B for scaling factors and
units.

APB - Autopilot Sentence "B"

Commonly used by autopilots this sentence contains navigation
receiver warning flag status, cross-track-error, waypoint arriv-
al status, initial bearing from origin waypoint to the destina-
tion, continuous bearing from present position to destination
and recommended heading-to-steer to destination waypoint for the
active navigation leg of the journey.

$--APB,A,A,x.x,a,N,A,A,x.x,a,c--c,...
| | | | | | | | | |
| | | | | | | | | +---Destination waypoint ID
| | | | | | | | +-----\M/T Magnetic or True
| | | | | | | +--------/Bearing origin to destination
| | | | | | +------------Status: A = perpendicular passed at waypoint
| | | | | +--------------Status: A = arrival circle entered
| | | | +----------------XTE units, nautical miles
| | | +------------------L/R Direction to steer
| | +---------------------Magnitude of XTE (cross-track-error)
| +------------------------Status: V = Loran-C Cycle Lock warning flag
| A = OK or not used
+--------------------------Status: V = Loran-C Blink or SNR warning
V = general warning flag for other navigation
systems when a reliable fix is not available

x.x,a,x.x,a*hh<CR><LF>
| | | |
| | | +-------------------\M/T Magnetic or True
| | +----------------------/Heading-to-steer to destination waypoint
| +-------------------------\M/T Magnetic or True
+----------------------------/Bearing, Present position to destination

*ASD - Autopilot System Data

I.M.O. Ref. A342 (IX). Autopilot operating parameters, alarm status
commanded course and vessel heading.

(TO BE DETERMINED)

BEC - Bearing & Distance to Waypoint - Dead Reckoning

Time (UTC) and distance & bearing to, and loacation of, a speci-
fied waypoint from the dead-reckoned present position.

$--BEC,hhmmss.ss,llll.ll,a,...
| | |
| | +-------\N/S North or South
| +--------------/Waypoint Latitude
+------------------------UTC of observation

c--c*hh<CR><LF>
|
+-----------------------------Waypoint ID

Page 23
BOD - Bearing - Origin to Destination

Bearing angle of the line, calculated at the origin waypoint, extend-
ing to the destination waypoint from the origin waypoint for the
active navigation leg of the journey.

BWC - Bearing & Distance to Waypoint - Great Circle
BWR - Bearing & Distance to Waypoint - Rhumb Line

Time (UTC) and distance & bearing to, and location of, a specified
waypoint from present position. '$--BWR' data is calculated along the
rhumb line from present position rather than along the great circle
path.

$--BWC,hhmmss.ss,llll.ll,a,...
| | |
| | +-------\N/S North or South
| +--------------/Waypoint latitude
+------------------------UTC of observation

c--c*hh<CR><LF>
|
+-----------------------------Waypoint ID

$--BWR,hhmmss.ss,llll.ll,a,...
| | |
| | +-------\N/S North or South
| +--------------/Waypoint latitude
+------------------------UTC of observation

c--c*hh<CR><LF>
|
+-----------------------------Waypoint ID

BWW - Bearing - Waypoint to Waypoint

Bearing angle of the line, between the "TO" and the "FROM" waypoints,
calculated at the "FROM" waypoint for any two arbitrary waypoints.

DBT - Depth Below Transducer

Water depth referenced to the transducer.

Page 24
DCN - Decca Position

Status and lines-of-position for a specified Decca chain.

cc,x.x,A,A,A,A,x.x,N,x*hh<CR><LF>
| | | | | | | | |
| | | | | | | | +---------Fix Data Basis [1]
| | | | | | | +----------\nautical miles
| | | | | | +-------------/Position uncertainty
| | | | | +-----------------Purple-line navigation use, A = valid
| | | | +-------------------Green -line navigation use, A = valid
| | | +---------------------Red -line navigation use, A = valid
| | +----------------------\
| +--------------------------PURPLE
+-----------------------------/

Notes:

[1] Fix Data Basis: 1 = Normal pattern
2 = Lane identification pattern
3 = Lane identification transmissions

*DPT - Depth

I.M.O. Ref. A224(VII). Water depth relative to the transducer and
offset of the measuring transducer. Positive offset numbers provide
the distance from the transducer to the waterline. Negative offset
numbers provide the distance from the transducer to the part oft the
keel of interest.

Motes:

* [1] For I.E.C applications the offset shall always be applied so as to
* provide depth relative to the keel.

*FSI - Frequency Set Information

This sentence is used to set frequency, mode of operation and trans-
mitter power level of a radiotelephone; to read out frequencies, mode
and power ant to acknowledge setting commands.

$--FSI,xxxxxx,xxxxxx,c,x+hh<CR><LF>
| | | |
| | | +----------Power level, 0 = Standby; 1 = lowest; 9 = highest
| | +------------Mode of operation [1]
| +-----------------Receiving frequency [2][3]
+------------------------Transmitting frequency [2][3]

Notes:

[1] Mode of operation:
d = F3E/G3E simplex, telephone w = F1B/J2B, teleprinter/DSC
e = F3E/G3E duplex, telephone x = A1A Morse, tape recorder
m = J3E , telephone { = A1A Morse, morse key/head set
o = H3E , telephone | = F1C/F2C/F3C, FAX-machine
q = F1B/J2B FEC NBDP, TELEX/teleprinter null for no information
s = F1B/J2B ARQ NBDP, TELEX/teleprinter
t = F1B/J2B receive only, teleprinter/DSC

Page 25
[2] Frequencies to be in 100 Hz increments.
MF/HF telephone channels to have first digit 3 followed by ITU channel
numbers with leading zeros as required.
MF/HF teletype channels to have first digit 4; the second ans
third digit frequency bands; and the fourth to sixth digits ITU channel
numbers; each with leading zeros as required.
VHF channels to have the first digit 9 followed by channel numbers
with leading zeros as required

[3] For paired frequencies zhe transmitting frequency only need to be in-
cluded; null for receiving frequency field. For receive frequency only,
the transmitting frequency field shall be null.

GGA - Global Positioning System Fix Data

Time, position and fix related data for a GPS receiver.

yyyyy.yy,a,x,xx,x.x,x.x,M,...
| | | | | | |
| | | | | | +-----\Units of antenna altitude, meters
| | | | | +--------/Antenna altitude above/below mean-sea-level (geoid)
| | | | +-------------Horizontal dilution of precision
| | | +-----------------Number of satellites in use, 00-12,
| | | may be different from the number in view
| | +-------------------GPS quality indicator [1]
| +--------------------\E/W East or West
+---------------------------/Longitude

x.x,M,x.x,xxxx*hh<CR><LF>
| | | |
| | | +-------------------Differential reference station ID, 0000-1023
| | +-----------------------Age of Differential GPS data [2]
| +-------------------------\Units of geoidal seperation, meters
+----------------------------/Geoidal seperation [3]

Notes:

[1] GPS quality indicator: 0 = fix not available or invalid
1 = GPS fix
2 = Differential GPS fix

[2] Time in seconds since last SC104 Type 1 or 9 update, null
field when DGPS is not used

[3] Geoidal Seperation: the difference between the WGS-84 earth
ellipsoid and mean-sea-level (geoid), "-" = mean-sea-level below
ellipsoid.

GLC - Geographic Position - Loran-C

Loran-C GRI, status and Time Difference (TD) lines of position for
present vessel position.

$--GLC,xxxx,x.x,a,x.x,a,x.x,a,...
| | | | | | |
| | | | | | +----\
| | | | | +-------/TD2 [2]
| | | | +----------\
| | | +-------------/TD1 [2]
| | +----------------\microseconds
| +-------------------/Master TOA [1]
+-------------------------GRI, microseconds/10

Page 26
Notes:

[1] Master TOA provides for direct ranging operation. It may be the
actual range to Master in microseconds or be offset and
track the arrival of the Master signal.

[2] Time difference numbers are in the Loran-C Coding Delay order
with null fields used when values are unavailable.

GLL - Geographic Position - Latitude/Longitude

Latitude and Longitude of present vessel position, time of position
fix and status.

A*hh<CR><LF>
|
+------------------------------Status: A = Data valid

GSA - GPS DOP and Active Satellites

GPS receivers operating mode, satellites used for navigation and
DOP values.

$--GSA,a,x,xx,xx,xx,xx,xx,xx,xx,...
| | | | | | | | |
| | | | | | | | +---|
| | | | | | | +------|
| | | | | | +---------|
| | | | | +------------|
| | | | +---------------|
| | | +------------------|PRN numbers of satellites used in
| | +---------------------/solution (null for unused fileds)
| +------------------------Mode: 1 = Fix not available
| 2 = 2D
| 3 = 3D
+--------------------------Mode: M = Manual, forced to operate in 2D or 3D mode
A = Automatic, allowed to automatically switch 2D/3D

xx,xx,xx,xx,xx,x.x,x.x,x.x*hh<CR><LF>
| | | | | | | |
| | | | | | | +------VDOP
| | | | | | +----------HDOP
| | | | | +--------------PDOP
| | | | +-----------------\
| | | +--------------------|
| | +-----------------------|
| +--------------------------|
+-----------------------------|

GSV - GPS Satellites in View

Number of SVs in view, PRN numbers, elevation, azimuth and SNR value.
Four satellites maximum per transmission, additional satellite data
sent in second or third message. Total number of messages being
transmitted and the number of the message being transmitted is indi-
cated in the first two fields.

$--GSV,x,x,xx,xx,xx,xxx,xx __________ ...
| | | | | | | |
| | | | | | | |
| | | | | | | +-2nd - 3rd SV [2]
| | | | | | |
| | | | | | +--------\SNR (C/No) 00-99 dB, null when not tracking
| | | | | +-----------|Azimuth, degrees True, 000 to 359
| | | | +---------------|Elevation, degrees, 90 deg maximum
| | | +------------------/Satellite PRN number
| | +----------------------Total number of satellites in view
| +------------------------Message number, 1 to 3 [1]
+--------------------------Total number of messages [1]

xx,xx,xxx,xx*hh<CR><LF>
| | | |
| | | +-------------------\
| | +----------------------|
| +--------------------------|
+-----------------------------/4th SV [2]

Page 27
Notes:

[1] Satellite information may require the transmission of multiple messages.
The first field specifies the total number of messages, minimum value 1.
The second field identifies the order of this message (message number),
minimum value 1.

[2] A variable number of 'PRN-Elevation-Azimuth-SNR' sets are allowed up to
a maximum of four sets per message. Null fields are not required for
unused sets when less than four sets are transmitted.

GXA - TRANSIT Position

Location and time of TRANSIT fix at waypoint "c--c":

$--GXA,hhmmss.ss,llll.ll,a,...
| | |
| | +-------\N/S North or South
| +-------------/Latitude
+------------------------UTC of position fix

yyyyy.yy,a,c--c,x*hh<CR><LF>
| | | |
| | | +--------------Satellite number
| | +------------------Waypoint ID
| +--------------------\E/W East or West
+---------------------------/Longitude

*HDG - Heading, Deviation & Variation

I.M.O. Ref. A382 (X). Heading (magnetic sensor reading), which if
corrected for deviation, will produce Magnetic heading, which if
offset by variation will provide True heading.

$--HDG,x.x,x.x,a,x.x,a*hh<CR><LF>
| | | | |
| | | | +-----------\E/W East or West [2] [3]
| | | +--------------/Magnetic variation, degrees
| | +-----------------\E/W East or West [1] [3]
| +--------------------/Magnetic deviation, degrees
+-------------------------Magnetic sensor heading, degrees

Notes:

[1] To obtain Magnetic heading:
Add Easterly deviation (E) to Magnetic Sensor Reading
Subtract Westerly deviation (W) from Magnetic Sensor Reading

[2] To obtain True Heading:
Add Easterly variation (E) to Magnetic Heading
Subtract Westerly variation (W) from Magnetic Heading

[3] Variation and deviation fields will be null fields if unknown.

*HDT - Heading - True

I.M.O. Ref. A424 (XI). Actual vessel heading in degrees True pro-
duced by any device or system producing true heading.

$--HDT,x.x,T*hh<CR><LF>
| |
| +---------------------\True
+------------------------/Heading, degrees

HSC - Heading Steering Command

Command heading to steer vessel.

$--HSC,x.x,T,x.x,M*hh<CR><LF>
| | | |
| | | +---------------\Magnetic
| | +------------------/Commanded heading, degrees
| +---------------------\True
+------------------------/Commanded heading, degrees

Page 28
LCD - Loran-C Signal Data

Signal-to-Noise ratio and pulse shape (ECD) data for Loran-C
signals.

$--LCD,xxxx,xxx,xxx,xxx,xxx,...
| | | | |
| | | | +-------\
| | | +-----------/S1 [1]
| | +---------------\
| +-------------------/Master
+-------------------------GRI, microseconds/10

xxx,xxx,xxx,xxx,xxx,xxx,...
| | | | | |
| | | | | +--------\
| | | | +------------/S4 [1]
| | | +----------------\
| | +--------------------/S3 [1]
| +------------------------\
+----------------------------/S2 [1]

xxx,xxx*hh<CR><LF>
| |
| +------------------------\Secondary5 [1] Relative ECD, 000 to +-999
+----------------------------/Secondary5 [1] Relative SNR, 000 to 999

Notes:

[1] Data is in the Loran-C Coding Delay order with null fields used
when values are unavailable.

MTW - Water Temperature

Water temperature.

$--MTW,x.x,C*hh<CR><LF>
| |
| +---------------------\degrees C
+------------------------/Temperature

*MWV - Wind Speed and Angle

When the Reference Field is set to Relative, data is provded giving
the wind angle in relation to the vessel's headig and wind speed,
both relative to the (moving) vessel.
When the Reference Field is set to True, data is provided giving the
wind angle relative to the vessel's heading and wind speed, both with
reference to the (moving) water. True wind is the vector sum of the
Relative (Apparent) wind vector and the vessel's velocity vector
along the heading line of the vessel. It represents the wind at the
vessel if it were stationary relative to the water and heading in the
same direction.

$--MWV,x.x,a,x.x,a,A*hh<CR><LF>
| | | | |
| | | | +--------------Status, A = Data Valid
| | | +---------------\Wind speed units, K/M/N
| | +------------------/Wind speed
| +---------------------\Reference: R = Relative
| T = True
+------------------------/Wind angle, 0 to 360 degrees

OLN - Omega Lane Numbers

Omega Lines of Positions (LOPs).

$--OLN,aa,xxx,xxx,aa,xxx,xxx,...
| | | | | |
| | | | | +------\
| | | | +----------|
| | | +--------------/pair 2
| | +-----------------\
| +---------------------|
+-------------------------/pair 1

aa,xxx,xxx*hh<CR><LF>
| | |
| | +---------------------\Centilane number
| +-------------------------|Lane number
+-----------------------------/pair 3, AB-GH

Page 29
*OSD - Own Ship Data

I.M.O. Ref. A477 (XII). Heading, course, speed, set and drift sum-
mary. Useful for, but not limited to RADAR/ARPA applications.

$--OSD,x.x,A,x.x,a,x.x,a,...
| | | | | |
| | | | | +---------\Speed Reference, B/M/W/R/P [1]
| | | | +------------/Vessel speed
| | | +---------------\Course Reference, B/M/W/R/P [1]
| | +------------------/Vessel Course, degrees True
| +---------------------\Heading Status: A = Data valid
+------------------------/Heading, degrees True

x.x,x.x,a*hh<CR><LF>
| | |
| | +---------------------\Speed units, K/N/S
| +------------------------|Vessel drift (speed) \ Manually
+----------------------------/Vessel set, degrees True / entered

Notes:

[1] Reference system: B = Bottom tracking log
M = Manually entered
W = Water referenced
R = RADAR tracking (of fixed target)
P = Positioning system ground reference

RMA - Recommended Minimum Specific Loran-C Data

Position, course and dpeed data provided by a Loran-C receiver. Time
differences A and B are those used in computing latitude/longitude.
Checksum is madatory in this entence. This sentence is transmitted
at intervals not exceeding 2-seconds and is always accompanied by RMB
when a destination waypoint is active. RMA and RMB are the recom-
mended minimum data to be provided by a loran receiver. All data
fields must be provided, null fields used only when data is tempo-
rarily unavailable.

$--RMA,A,llll.ll,a,yyyyy.yy,a,...
| | | | |
| | | | +----\E/W East or West
| | | +-----------/Longitude
| | +---------------\N/S North or South
| +---------------------/Latitude
+--------------------------Status: V = Blink, Cycle or SNR warning

x.x,x.x,x.x,x.x,x.x,a*hh<CR><LF>
| | | | | | |
| | | | | | +--------Checksum mandatory for RMA
| | | | | +---------\E/W East or West
| | | | +------------/Magnetic variation [1], degrees
| | | +-----------------Track Made Good, degrees True
| | +---------------------Speed over ground, knots
| +-------------------------Time difference B, uS
+-----------------------------Time difference A, uS

Notes:

[1] Easterly variation (E) subtracts from True course
Westerly variation (W) adds to True course

Page 30
RMB - Recommended Minimum Navigation Information

Navigation data from present position to a destination waypoint
provided ba a Loran-C, TRANSIT, OMEGA, GPS, DECCA, navigation
computer or other integrated navigation system. Checksum is
mandatory in this sentence. This semtemce always accompanies RMA or
RMC sentences when a destination is active when provided by a Loran-
C, TRANSIT or GPS receiver, other systems may transmit $--RMB without
$--RMA or $--RMC.

$--RMB,A,x.x,a,c--c,c--c,...
| | | | |
| | | | +------------Destination waypoint ID
| | | +-----------------Origin waypoint ID
| | +-------------------\Direction to steer - L/R Left or Right
| +----------------------/Cross track error - nautical miles [2]
+--------------------------Data status: V = Navigation receiver warning

llll.ll,a,yyyyy.yy,a,...
| | | |
| | | +----------\E/W East or West
| | +-----------------/Destination wpt. longitude
| +---------------------\N/S North or South
+---------------------------/Destination wpt. latitude

x.x,x.x,x.x,A*hh<CR><LF>
| | | | |
| | | | +----------------Checksum, mandatory for RMB
| | | +------------------Arrival status: A = arrivalcircle entered or perpendicular passed
| | +---------------------Destination closing velocity, knots
| +-------------------------Bearing to destination, degrees True
+-----------------------------Range to destination, nautical miles [1]

Notes:

[1] If range to destination exceeds 999.9 NM, display 999.9

[2] if cross track error exceeds 9.99 NM, display 9.99

RMC - Recommended Minimum Specific GPS/TRANSIT Data

Time, date, position, course and speed data provided by a GPS or
TRANSIT navigation receiver. Checksum is mandatory in this sen-
tence. This sentence is transmitted at intervals not exceeding 2-
secondes and is always accompanied by RMB when a destination waypoint
is active. RMC and RMB are recommended minimum data to be pro-
vided by a GPS or TRANSIT receiver. All data fields must be provid-
ed, null fields used only when data is temporarily unavailable.

$--RMC,hhmmss.ss,A,llll.ll,a,...
| | | |
| | | +-----\N/S North or South
| | +-----------/Latitude
| +----------------Status: V = Nav. receiver warning
+------------------------UTC of position fix

x.x,a*hh<CR><LF>
| | |
| | +------------------------Checksum, mandatory for RMC
| +-------------------------\E/W East or West [1]
+----------------------------/Magnetic variation, degrees

Notes:

[1] Easterly variation (E) subtract from True course
Westerly variation (W) adds to True course

Page 31
*ROT - Rate of Turn

I.M.O. Ref. A526 (XIII). Rate of turn and direction of turn.

$--ROT,x.x,A*hh<CR><LF>
| |
| +----------------------Status: A = Data valid
+-------------------------Rate of turn, degrees/minute, "-" = bow turns to port

*RPM - Revolutions

I.M.O. Ref. (none). Shaft or engine revolution rate and propeller
pitch.

$--RPM,a,x,x.x,x.x,A*hh<CR><LF>
| | | | |
| | | | +--------------Status: A = Data valid
| | | +-----------------Propeller pitch, % of max., "-" = astern
| | +---------------------Speed, rev/min, "-" = counter-clockwise
| +------------------------Engine or shaft number, numbered from center-
| line, odd = starboard, even = port, 0 = single
| or on center-line
+--------------------------Source: Shaft/Engine - S/E

*RSA - Rudder Sensor Angle

I.M.O. Ref. (none). Relative rudder angle, from rudder angle sensor.

$--RSA,x.x,A,x.x,A*hh<CR><LF>
| | | |
| | | +---------------\Status A = Valid
| | +------------------/Port rudder sensor [1]
| +---------------------\Status A = Valid
+------------------------/Starboard (or single) rudder sensor [1]

*RSD - RADAR System Data

I.M.O. Ref. A477 (XII). RADAR screen setting data.

$--RSD,x.x,x.x,x.x,x.x,x.x,x.x,...
| | | | | |
| | | | | +-----Origin2 bearing
| | | | +---------Origin2 range
| | | +-------------Bearing Line 1 (EBL1), degrees from 0 deg
| | +-----------------Variable Range Marker 1 (VRM1), range
| +---------------------Origin1 bearing, degrees from 0 deg
+-------------------------Origin1 range , from own ship

x.x,x.x,x.x,x.x,x.x,a,a*hh<CR><LF>
| | | | | | |
| | | | | | +--------Display rotation [1]
| | | | | +----------Range units, K/N/S
| | | | +-------------Range scale (maximum)
| | | +-----------------Cursor bearing, degrees CW from 0 deg.
| | +---------------------Cursor range, from own ship
| +-------------------------EBL2, degrees
+-----------------------------VRM2, range

Notes:

[1] Display rotation: C = Course-up, course-over-ground up, degrees True
H = Head -up, ship's heading (center-line) 0 deg up
N = North -up, True north is 0 deg up

Page 32
RTE - Routes

Waypoint identifiers, listed in order with starting waypoint first,
for the identified route. Two mode of transmission are provided:
'c' indicates that the complete list of waypoints in the route are
being transmitted; 'w' indicates a working route where the first
listed waypoint is always the last waypoint that had been reached
(FROM), while the second listed waypoint is always the waypoint that
the vessel is currently heading for (TO), the remaining list of
waypoints represents the remainder of the route.

$--RTE,x.x,x.x,a,c--c,c--c,...
| | | | |
| | | | +----------Waypoint identifier
| | | +---------------Route identifier
| | +------------------Message mode: c = complete route, all waypoints
| | w = working route, 1st listed waypoint
| | is 'FROM', 2nd is 'TO' and remain-
| | ing are rest of route
| +---------------------Message number [2]
+-------------------------Total number of messages being transmitted [2]

______ c--c*hh<CR><LF>
| |
| +----------------------Waypoint 'n' identifier [1]
+----------------------------Additional waypoint identifiers [1]

Notes:

[1] A variable number of waypoint identifiers, up to 'n', may be in
included within the limits of allowed sentence length. As there is
no specified number of waypoints, null fields are not required for
Waypoint Identifier fields.

[2] A single route may require the transmission of multipe messages.
The first field specifies the total number of messages, minimum
value = 1. The second field identifies the order of this message
(message number), minimum value = 1.

*SFI - Scanning Frequency Information

This sentence is used to set frequencies and mode of operation for
scanning purposes and to acknowledge setting commands. Scanning
frequencies are listed in order of scanning.

Note:
For DSC distress and safety watchkeeping only 6 channels shall be
scanned in the same scanning sequence.
To indicate a frequency set at the scanning receiver use FSI sen-
tence.

$--SFI,x.x,x.x,xxxxxx,c _______ ...
| | | | |
| | | | +-------2nd - 5th frequency, mode [3]
| | | +----------\Mode of operation [1]
| | +---------------/1st frequency or ITU channel [2]
| +---------------------Message number [4]
+-------------------------Total number of messages being transmitted [4]

xxxxxx,c*hh<CR><LF>
| |
| +----------------------\mode [3]
+---------------------------/6th frequency

Page 33
Notes:

[2] Frequencies to be in 100 Hz increments.
MF/HF telephone channels to have first digit 3 followed by ITU
channel numbers with leading zeros as required.
MF/HF teletype channels to have first digit 4; the second and
third digit frequency bands; and the fourth to sixth digits ITU
channel numbers; each with leading zeros as required.
VHF channels to have first digit 9 followed by channel number with
leading zeros as required.

[3] A variable number of frequency-mode pair fields are allowed up to a
maximum of six pairs. Null fields are not required for unused pairs
when less than six pairs are transmitted.

[4] Scanning frequency information may require the transmision of
multiple messages. The first field specifies the total number of
messages, minimum value = 1. The second field identifies the order
of this message (message number), minimum value = 1.

STN - Multiple Data ID

This sentence is transmitted before each individual sentence where
there is a need for the Listener to determine the exact source of
data in a system. Examples might include dual-frequency depthsound-
ing equipment or equipment that integrates data from a number of
sources and produces a single output.

$--STN,xx*hh<CR><LF>
|
+--------------------------Talker ID number, 00 to 99

TRF - TRANSIT Fix Data

Time, date, position and information related to a TRANSIT fix.

yyyyy.yy,a,x.x,x.x,x.x,x.x,...
| | | | | |
| | | | | +------Update distance, nautical miles
| | | | +----------Number of Doppler intervals
| | | +--------------Number of iterations
| | +------------------Elevation angle
| +--------------------\E/W East or West
+---------------------------/Longitude

xxx,A*hh<CR><LF>
| |
| +--------------------------Data status: warning flag
+-----------------------------Satellite ID

Page 34
*TTM - Tracked Target Message

I.M.O. Ref. A477 (XII). Data associated with a tracked target rela-
tive to own ship's position.

$--TTM,xx,x.x,x.x,a,x.x,x.x,a,...
| | | | | | |
| | | | | | +----\true/relative - T/R
| | | | | +-------/Target course, degrees
| | | | +------------Target speed
| | | +--------------\true/relative - T/R
| | +-----------------/Bearing from own ship, degrees
| +----------------------Target distance, from own ship
+--------------------------Target number, 00 to 99

x.x,x.x,a,c--c,a,a*hh<CR><LF>
| | | | | |
| | | | | +-------------Reference target = R, null otherwise
| | | | +---------------Target status [1]
| | | +-------------------User data (eg. target name)
| | +----------------------Minutes
| +-------------------------Time to CPA, "-" increasing
+-----------------------------Distance of closest-point-of-approach

Notes:

[1] Target status: L = Lost, tracked target has been lost
Q = Query, target in the process of acquisition
T = Tracking

*VBW - Dual Ground/Water Speed

Water referenced and ground referenced speed data.

$--VBW,x.x,x.x,A,x.x,x.x,A*hh<CR><LF>
| | | | | |
| | | | | +--------Status: Ground speed, A = Data valid
| | | | +-----------Transverse ground speed [1], knots
| | | +---------------Longitudinal ground speed [1], knots
| | +------------------Status: Water speed, A = Data valid
| +---------------------Transverse water speed [1], knots
+-------------------------Longitudinal water speed [1], knots

Notes:

[1] Transverse speed: "-" = port, Longitudinal speed: "-" = astern

VDR - Set and Drift

The direction towards which a current flows (Set) and speed
(Drift) of a current.

VHW - Water Speed and Heading

The compass heading to which the vessel points and the speed of
the vessel relative to the water.

Page 35
VLW - Distance Traveld through the Water

The distance traveled, relative to the water.

$--VLW,x.x,N,x.x,N*hh<CR><LF>
| | | |
| | | +---------------\nautical miles
| | +------------------/Distance since reset
| +---------------------\nautical miles
+------------------------/Total cumulative distance

VPW - Speed Measured Parallel to Wind

The component of the vessel's velocity vector parallel to the
direction of the true wind direction. Sometimes called "speed
made good to windward" or "velocity made good to windward".

$--VPW,x.x,N,x.x,M*hh<CR><LF>
| | | |
| | | +---------------\meters/second
| | +------------------/Speed, "-" = downwind
| +---------------------\knots
+------------------------/Speed, "-" = downwind

VTG - Track Made Good and Ground Speed

The actual track made good and speed relative to the ground.

WCV - Waypoint Closure Velocity

The component of the velocity vector in the direction of the
waypoint, from present position. Sometimes called "speed made
made good" or "velocity made good".

$--WCV,x.x,N,c--c*hh<CR><LF>
| | |
| | +-------------------Waypoint identifier
| +---------------------\knots
+------------------------/Velocity component

WNC - Distance - Waypoint to Waypoint

Distance between two specified waypoints.

WPL - Waypoint Location

Latitude and longitude of specified waypoint.

Page 36
XDR - Transducer Measurements

Measurement data from transducers that measure physical quantities
such as temperature, force, pressure, frequency, angular or linear
displacement, etc. Data from a variable number transducers measuring
the same or different quantities can be mixed in the same sentence.
This sentence is designed for use by integrated systems as well as
transducers that may be connected in a 'chain' where each transducer
receives the sentence as an input and adds its own data fields on
before retransmitting the sentence.

$--XDR,a,x.x,a,c--c, ________ ...
| | | | |
| | | | +---------Data for variable # of transducers
| | | +----------------\Transducer #1 ID
| | +-------------------|Units of measure, Transducer #1 [2]
| +----------------------|Measurement data, Transducer #1
+-------------------------/Transducer type, Transducer #1 [2]

a,x.x,a,c--c*hh<CR><LF>
| | | |
| | | +--------------------\
| | +-----------------------|
| +--------------------------|
+-----------------------------/Transducer 'n' [1]

Notes:

[1] Sets of the four fields 'Type-Data-Units-ID' are allowed for an unde-
fined number of transducers. Up to 'n' transducers may be included
within the limits of allowed sentence length, null fields are not re-
quired except where portions of the 'Type-Data-Units-ID' combination are
not available.

[2] Allowed transducer types and their units of measure are:

Transducer Type Field Units Field Comments

temperature C C = degrees Celsius
angular displacement A D = degrees "-" = anticlockwise
linear displacement D M = meters "-" = compression
frequency F H = Hertz
force N N = Newtons "-" = compression
pressure P B = Bars "-" = vacuum
flow rate R l = liters/second
tachometer T R = RPM
humidity H P = Percent
volume V M = cubic meters

XTE - Cross-Track Error - Measured

Magnitude of the position error perpendicular to the intended track
line and the direction to steer to reduce the error.

$--XTE,A,A,x.x,a,N*hh<CR><LF>
| | | | |
| | | | +---------------\Units, nautical miles
| | | +-----------------|Direction to steer, L/R Left or right
| | +--------------------/Magnitude of Cross-Track-Error
| +------------------------Status: V = Loran-C Cycle Lock warning flag
| A = OK or not used
+--------------------------Status: V = Loran-C Blink or SNR warning
V = general warning flag for other navigation
system when a reliable fix is not available

Page 37
XTR - Cross-Track Error - Dead Reckoning

Magnitude of the dead reckoned position error perpendicular to
the intended track line and the direction to steer to reduce the
error.

$--XTR,x.x,a,N**hh<CR><LF>
| | |
| | +-------------------\Units, nautical miles
| +---------------------|Direction to steer, L/R Left or right
+------------------------/Magnitude of Cross-Track-Error

ZDA - Time & Date

UTC, day, month, year and local time zone.

$--ZDA,hhmmss.ss,xx,xx,xxxx,xx,xx*hh<CR><LF>
| | | | | |
| | | | | +--Local zone minutes description, same sign as local hours
| | | | +-----Local zone description [1], 00 to +-13 hrs
| | | +---------Year
| | +-------------Month, 01 to 12
| +----------------Day , 01 to 31
+------------------------UTC

Notes:

[1] Zone description is the number of whole hours added to local
time to obtain GMT, Zone description is negative for East
longitudes.

ZFO - UTC & Time from Origin Waypoint

UTC and elapsed time from origin waypoint.

$--ZFO,hhmmss.ss,hhmmss.ss,c--c*hh<CR><LF>
| | |
| | +-----Origin waypoint ID
| +--------------Elapsed time
+------------------------UTC of observation

ZTG - UTC & Time to Destination Waypoint

UTC and predicted time-to-go to destination waypoint.

$--ZTG,hhmmss.ss,hhmmss.ss,c--c*hh<CR><LF>
| | |
| | +-----Destination waypoint ID
| +--------------Time-to-go
+------------------------UTC of observation

Page 38
7. Applications

7.1 Example Sentences

These examples are intended as samples of correct constructed sentences.
They are representative samples only and show part of the wide range of
legal variations possible with sentences. They should not necessarily be
used as templates for sentences.

7.1.1 Example #1, Loran-C LAT/LONG

This example gives present position in Lat-Long, as determined by LoranC.
The 3 character mnemonic in the address, GLL, indicates that the data is
present position in Lat.-Long. The time (UTC) of the position fix is 09
hours, 13 minutes and 42 seconds. Decimal seconds are not available and
the decimal point is optionally omitted. There are no warning flags set in
the navigation receiver as indicated by Status = 'A'.

$LCGLL,4728.31,N,12254.25,W,091342,A*21<CR><LF>
| | | | | | | | | |
| | | | | | | | | +--Sentence Terminator
| | | | | | | | +-------Checksum 21HEX
| | | | | | | +---------Receiver status: no warnings
| | | | | | +--------------Time of position fix
| | | | | +-----------------\Units Designator (West)
| | | | +------------------------/Long. 122 Degrees, 54.25 Minutes
| | | +----------------------------\Units Designator (North)
| | +----------------------------------/Lat. 47 Degrees, 28.31 Minutes
| +-----------------------------------------Address: LC = Loran-C
| GLL = Present Position
+--------------------------------------------Start of sentence

7.1.2 Example #2, Loran-C Arrival Alarm

This example illustrates Arrival Alarm data. The mnemonic code for Arrival
Alarm is AAM. In this case the address Field is "LCAAM" for Loran-C Arriv-
al Alarm. The first data field shows "V" indicating the radius of the
arrival circle HAS NOT been entered, the second data field is "A" showing
that the perpendicular to the course line, at the destination, HAS been
crossed. The third and fourth fields show the radius and units of the
destination waypoint arrival circle ".15,N" for 0.15 nautical miles. Data
field five is the Waypoint Identifier field of valid characters.

$LCAAM,V,A,.15,N,CHAT-N6*56<CR><LF>
| | | | | | | | |
| | | | | | | | +--------------Sentence Terminator
| | | | | | | +-------------------Checksum 56HEX
| | | | | | +------------------------Identifier for waypoint "CHAT-N6"
| | | | | +----------------------------\Units of arrival circle, nautical miles
| | | | +-------------------------------/Radius of arrival circle, 0.15
| | | +-----------------------------------Status: perpendicular has been crossed
| | +-------------------------------------Status: arrival circle has not been entered
| +-----------------------------------------Address: LC = Loran-C
+-------------------------------------------- AAM = Start of Sentence

Page 39
7.1.3 Example #3 - Proprietary Sentence

A proprietary sentence has the following general format:

|<--- 80 character Sentence or less --->|
v v

$Paaa-----------------------------------<CR><LF>
|| | | | |
|| | +--> data, 75 character maximum <--+ +--> End of sentence
|| |
|| +----> 3 character manufacturer's mnemonic code
||
|+------> Proprietary sentence identifier
|
+-------> Start of sentence

A specific example will have little meaning to someone other than
the particular manufacturer that designed the sentence:

$PSRDA003[470738][1224523]???RST47,3809,A004*47<CR><LF>
|| | | | | |
|| | +> any serie of valid (non-reserved) <+ | +--> End of Sentence
|| | +> characters of manufacturers choice<+ +--------> Checksum 47HEX
|| |
|| +--> Unique manufacturer's assigned code
||
|+----> Proprietary sentence identifier
|
+-----> Start of sentence

7.1.4 Example #4 - RMA Examples

The following group of sentences show a typical progression of
output data as a Loran-C receiver acquires stations:

a) $LCRMA,V,,,,,14162.8,,,,,*0D<CR><LF>
Data invalid, only one TD acquired. Fields where data is
not yet available are null fields.

b) $LCRMA,V,,,,,14172.3,26026.7,,,,*2E<CR><LF>
Two TDs acquired but not settled, data invalid.

c) $LCRMA,A,,,,,14182.3,26026.7,,,,*36<CR><LF>
Data valid, two TDs cycled but Lat/Lon not yet calculated.

d) $LCRMA,A,4226.26,N,07125.89,W,14182.3,26026.7,8.5,275.,14.0,W*68<CR><LF>
Normal operation

e) $LCRMA,V,4226.26,N,07125.89,W,14182.3,26026.7,8.5,275.,14.0,W*7F<CR><LF>
Data invalid, potential Loran problem.

f) $LCRMA,A,4226.265,N,07125.890,W,14182.33,26026.71,8.53,275.,14.0,W*53<CR><LF>
Loran operating in high resolution mode.

Page 40
7.1.5 Example #5 - FSI Examples

The following sentences show typical applications for remote
control of radiotelephones:

a) $--FSI,020230,026140,m,0*hh<CR><LF>
Set transmitter 2023 kHz, receiver 2614 kHz, mode J3E,
telephone, standby.

b) $CTFSI,020230,026140,m,5*11<CR><LF>
MF/HF radiotelephone set transmit 2023 kHz, receive
2614 kHz, mode J3E, telephone, medium power.

c) $--FSI,,021820,o,*hh<CR><LF>
Set receiver 2182 kHz, mode H3E, telephone.

d) $CDFSI,900016,,d,9*08<CR><LF>
Set VHF transmit and receive channel 16, F3E/G3E
simplex, telephone, high power.

e) $--FSI,300821,,m,9*hh<CR><LF>
Set MF/HF radiotelephone to telephone channel 821 e.g.
transmit 8 255 kHz, receive 8 779 kHz, mode J3E,
telephone, high power.

f) $--FSI,404001,,w,5*hh<CR><LF>
Set MF/HF radiotelephone to telephone channel 1 in 4 MHz
band e.g. transmit 4 172.5 kHz, receive 4 210.5 kHz,
mode F1B/J2B, teleprinter, medium power.

g) $CTFSI,416193,,s,0*00<CR><LF>
MF/HF radiotelephone tuned to teletype channel 193 in
16 MHz band e.g. transmitter 16 784.5 kHz, receiver
16 902.5kHz, mode F1B/J2E ARQ, TELEX/teleprinter, standby.

h) $--FSI,041620,043020,|,9*hh<CR><LF>
Set MF/HF radiotelephone transmit 4 162 kHz, receive
4 302 kHz, mode F1C/F2C/F3C, FAX-machine, high power.

i) $CXFSI,,021875,t,*3A<CR><LF>
Scanning receiver set 2 187.5 kHz, mode F1B/J2B receive
only, teleprinter/DSC.

Page 41
7.2 Receiver Diagrams

The illustrative diagrams in Figure 3 and Figure 4 show the structure of
two optoisolator based LISTENER circuits that offer overvoltage, reverse
voltage and power dissipation protection for the optoisolator and serve-
limit the current drawn from the line.

N-CHANNEL OPTO-ISOLATOR
JFET - - - - - - - -
____ | |
A O-------+ +-----|____|---*---------+ +------
| | | | |
----- | | | | |
^ | | |
| | _|_ |
| --- | \ | / / |
- /|\ \|/ \|\ |/
| | /_|_\ --- \| |
| | | | | - |\| |
| | | | -\
| | | | |
- | | | | |
| | | |
| | | |
B O---------*----------------*---------+ +------
| |
- - - - - - - -

(Figure 3)

OPTO-ISOLATOR
- - - - - - - -
____ | |
A O-------|____|---*---*---------------+ +------
| | | |
| | | | | |
| | | |
| | _|_ |
--- | | \ | / / |
/|\ | NPN \|/ \|\ |/
/_|_\ \ --- \| |
| \| | | - |\| |
| |-----+ | -\
| |/| | | |
| /- | | | | |
| | | | |
| | ____ | | |
B O----------------*---*-|____|-*------+ +------
| |
- - - - - - - -

(Figure 4)

End of NMEA 0183 Version 2.00

Page 42
STANDARD FOR INTERFACING MARINE ELECTRONIC DEVICES
NMEA 0183 Version 2.00 Appendix I

NMEA 0183 APPENDIX I

Version 2.00

Januar 1, 1992

Sentences Not Recommended for New Designs

The following identifiers and senteces are scheduled to be phased out
of use and are no longer recommended for sole use in new or revised
designs. The senteces are valid sentences, but due to changing
circumstances it is desirable to delete or replace these sentences as
indicated below.

Generally in each of the sentence descriptions below reference is made
to a sentence in the current Version of the standard, manufacturers
are urged to use the currently recommended sentence in new or revised
designs. It is desirable that manufacturers provide both new and old
sentences whenever possible for a period of time that will serve as a
phase-in period for the new sentences.

TABLE I-1 - TALKER IDENTIFIER MNEMONICS

TALKER DEVICE IDENTIFIER

COMPUTER
Programmed Calc. CC
Memory data CM
Microwave Positioning System MP
Distress Alarm System OS
TRANSDUCERS
Temperature YC
Displacement, Angular or Linear YD
Frequency YF
Level YL
Pressure YP
Flow Rate YR
Tachometer YT
Volume YV

TABLE I-2 - SENTENCE FORMATTERS NOT RECOMMENDED FOR NEW DESIGNS

APA - Autopilot Sentence "A"......................................4
BER - Bearing & Distance to Waypoint, Dead Reckoning, Rhumb Line..4
BPI - Bearing & Distance to Point of Interest.....................4
DBK - Depth Below Keel............................................4
DBS - Depth Below Surface.........................................4
DRU - DUAL DOPPLER AUXILIARY DATA.................................5
GDa - Dead Reckoning Positions....................................5
GLa - Loran-C Positions...........................................5

Page I-01
GOa - OMEGA Positions.............................................5
GXa - TRANSIT Positions...........................................5
GTD - Geographical Position, Loran-C TDs..........................6
HCC - Compass Heading.............................................6
HCD - Heading and Deviation.......................................6
HDM - Heading, Magnetic...........................................6
HVD - Magnetic Variation, Automatic...............................7
HVM - Magnetic Variation, Manually Set............................7
IMA - Vessel Identification.......................................7
MHU - Humidity....................................................7
MMB - Barometer...................................................7
MTA - Air Temperature.............................................7
MWD - Wind Direction and Velocity, Surface........................8
MWH - Wave Height.................................................8
MWS - Wind & Sea State............................................8
OLW - Omega Lane Width............................................8
OMP - OMEGA Pairs.................................................8
ONZ - Omega Zone Number...........................................8
Rnn - Routes......................................................8
SBK - Loran-C Blink Status........................................9
SCY - Loran-C Cycle Lock Status...................................9
SCD - Loran-C ECDs................................................9
SDB - Loran-C Signal Strength.....................................9
SGD - Position Accuracy Estimate..................................9
SGR - Loran-C Chain Identifier....................................9
SIU - Loran-C Stations in Use.....................................9
SLC - Loran-C Status.............................................10
SNC - Navigation Calculation Basis...............................10
SNU - Loran-C SNR Status.........................................10
SPS - Loran-C Predicted Signal Strength..........................10
SSF - Position Correction Offset.................................10
STC - Time Constant..............................................11
STR - Tracking Reference.........................................11
SYS - Hybrid System Configuration................................11
TEC - TRANSIT Satellite Error Code & Doppler Count...............11
TEP - TRANSIT Satellite Predicted Elevation......................11
TGA - TRANSIT Satellite Antenna & Geoidal Heights................11
TIF - TRANSIT Satellite Initial Flag.............................12
TRP - TRANSIT Satellite Predicted Direction of Rise..............12
TRS - TRANSIT Satellite Operating Status.........................12
VCD - Current at Selected Depth..................................12
VPE - Speed, Dead Reckoned Parallel to True Wind.................12
VTA - Actual Track...............................................12
VTI - Intended Track.............................................13
VWE - Wind Track Efficiency......................................13
WDC - Distance to Waypoint.......................................13
WDR - Waypoint Distance, Rhumb Line..............................13
WFM - Route Following Mode.......................................13
WNR - Waypoint-to-Waypoint Distance, Rhumb Line..................13
YWP - Water Propagation Speed....................................14
YWS - Water Profile..............................................14
Zaa - Time, Elapsed/Estimated....................................14
ZCD - Timer......................................................15
ZEV - Event Timer................................................15
ZLZ - Time of Day................................................15
ZZU - Time, UTC..................................................15

Page I-02
APA - Autopilot Sentence "A"

Commonly used by autopilots this sentence contains navigation
receiver warning flag status, cross-track-error, waypoint arriv-
al status and initial bearing from origin waypoint to the desti-
nation waypoint for the active navigation leg of journy.

Use of $--APB with additional data fields of heading-to-steer
and bearing from present position to destination is recommended.

$--APA,A,A,x.x,a,N,A,A,x.x,M,c--c*hh<CR><LF>
| | | | | | | | | |
| | | | | | | | | +---Destination waypoint ID
| | | | | | | | +-----\Magnetic
| | | | | | | +--------/Bearing origin to destination
| | | | | | +------------Status: perpendicular passed at waypoint
| | | | | +--------------Status: arrival circle entered
| | | | +---------------\XTE units, Nautical miles
| | | +-----------------|Direction to steer, L/R
| | +--------------------/Magnitude of XTE (cross-track-error)
| +------------------------Data status: Loran-C Cycle Lock warning flag
+--------------------------Data status: "OR" of Loran-C Blink and SNR warning flags

BER - Bearing & Distance to Waypoint, Dead Reckoning, Rhumb Line
BPI - Bearing & Distance to Point of Interest

Time (UTC) and distance & bearing to, and locationof, a speci-
fied waypoint from present position:

BER: Calculated along the rhumb line from dead reckoned
present position. The use of $--BEC using great circle
calculations is recommended.

BPI: Calculated along a great circle path from measured
present position. Redundant with BWC, the use of
$--BWC is recommended.

$--BER,hhmmss.ss,llll.ll,a,...
$--BPI,... | | |
| | +-------\N/S North or South
| +--------------/Waypoint latitude
+----------------------UTC of observation

c--c*hh<CR><LF>
|
+-----------------------------Waypoint ID

DBK - Depth Below Keel
DBS - Depth Below Surface

Water depth referenced to the vessel's keel (DBK) or to the
water surface (DBS).

The use of $--DPT is recommended in place of either of these.

Page I-03
DRU - DUAL DOPPLER AUXILIARY DATA

Depth, turn rate and % RPM in support of Doppler velocity sys-
tems.

The use of $--DPT is recommended for depth data, $--RPM for
shaft rotation and $--ROT for rate of turn.

$--DRU,x.x,A,x.x,A,x.x*hh<CR><LF>
| | | | |
| | | | +-------------Propeller shaft rotation, % of maximum
| | | +---------------\Status: Rate of turn
| | +------------------/Rate of turn, degrees per minute, "-" = port
| +---------------------\Status: Depth
+------------------------/Depth

GDa - Dead Reckoning Positions
GLa - Loran-C Positions
GOa - OMEGA Positions
GXa - TRANSIT Positions

Location and time at waypoint "c--c":
$--aaF: predicted or estimated time
$--aaP: present position and time
$--aaA: past position and time

The use of waypoint location $--WPL (for past positions) or
$--GLL (for present position) followed by time tag $--ZDA is
recommended for reporting past or present waypoint times; $--WPL
followed by $--ZTG is recommended for estimated time.

Dead reckoned positions:
$--GDF,hhmmss.ss,llll.ll,a,...
$--GDP,...| | |
$--GDA,...| | +--------\N/S North or South
| +--------------/Latitude
+------------------------UTC of position fix

yyyyy.yy,a,c--c*hh<CR><LF>
| | |
| | +-------------------Waypoint ID
| +---------------------\E/W East or West
+----------------------------/Longitude

Loran-C determined positions:
$--GLF,...
$--GLP,...
$--GLA,...

Omega determined positions:
$--GOF,...
$--GOP,...
$--GOA,...

TRANSIT determined positions:
$--GXF,hhmmss.ss,llll.ll,a,...
$--GXP,...| | |
| | +--------\N/S North or South
| +--------------/Latitude
+------------------------UTC of position fix

yyyyy.yy,a,c--c,x*hh<CR><LF>
| | | |
| | | +---------------Satellite number
| | +-------------------Waypoint ID
| +---------------------\E/W East or West
+----------------------------/Longitude

Page I-04
GTD - Geographical Position, Loran-C TDs

Loran-C Time Difference (TD) lines of position for present
vessel position.

The use of $--GLC is recommended.

$--GTD,x.x,x.x,x.x,x.x,x.x*hh<CR><LF>
| | | | |
| | | | +---------TD 5, micro-seconds
| | | +-------------TD 4, micro-seconds
| | +-----------------TD 3, micro-seconds
| +---------------------TD 2, micro-seconds
+-------------------------TD 1, micro-seconds

HCC - Compass Heading

Vessel compass heading, which differs from magnetic heading by
the amount of uncorrected magnetic variation.

The use of $--HDG is recommended.

$--HCC,x.x*hh<CR><LF>
|
+-------------------------Compass heading, degrees

HCD - Heading and Deviation

Actual Vessel magnetic heading, indicated compass heading and
the difference (deviation) between them.

The use of $--HDG is recommended.

Note:

[1] Easterly deviation (E) subtracts from Compass Heading
Westerly deviation (W) adds to Compass Heading

HDM - Heading, Magnetic

Actual vessel heading in degrees Magnetic.

The use of $--HDG is recommended.

$--HDM,x.x,M*hh<CR><LF>
| |
| +---------------------\degrees Magnetic
+------------------------/Heading

Page I-05
HVD - Magnet Variation, Automatic
HVM - Magnet Variation, Manually Set

Magnetic Variation, automatically derived (calculated or taken
from a data base) (HDV), or manually entered (HVM).

The use of $--HDG is recommended.

$--HVD,x.x,a*hh<CR><LF>
$--HVM,x.x,a*hh<CR><LF>
| |
| +---------------------\degrees E/W [1]
+------------------------/Magnetic variation

Note:

[1] Easterly variation (E) subtracts from True Heading
Westerly variation (W) adds to True Heading

IMA - Vessel Identification

Limited utility, no recommended replacement.

$--IMA,aaaaaaaaaaaa,aaaxxxx,...
| |
| +----------Radio call sign
+---------------------12 character vessel name

MDA - Meteorological Composite

Barometric pressure, air and water temperature, humidity, dew
point and wind speed and direction relative to the surface of the
earth.

The use of $--MTW, $--MWV and $--XDR is recommended.

Page I-06
MHU - Humidity

The use of $--XDR is recommended.

$--MHU,x.x,x.x,x.x,C*hh<CR><LF>
| | | |
| | | +-------------\degrees C
| | +----------------/Dew point
| +---------------------Absolute humidity, percent
+-------------------------Relative humidity, percent

MMB - Barometer

The use of $--XDR is recommended.

$--MMB,x.x,I,x.x,B*hh<CR><LF>
| | | |
| | | +---------------\bars
| | +------------------/Barometric pressure
| +---------------------\inches of mercury
+------------------------/Barometric pressure

MTA - Air Temperature
MTW - Water Temperature

The use of $--XDR is recommended.

$--MTA,x.x,C*hh<CR><LF>
$--MTW,x.x,C*hh<CR><LF>
| |
| +-----------\degrees C
+--------------/Temperature

MWD - Wind Direction and Velocity, Surface

The use of $--MWV is recommended.

MWH - Wave Height

Limited utility, no recommended replacement.

MWS - Wind & Sea State

Limited utility, no recommended replacement.

$--MWS,xx,xx*hh<CR><LF>
| |
| +-----------------------Beaufort Sea State Code
+--------------------------Beaufort Wind Force Code

OLW - Omega Lane Width

Limited utility, no recommended replacement.

Page I-07
OMP - OMEGA Pairs

Limited utility, no recommended replacement.

ONZ - Omega Zone Number

Limited utility, no recommended replacement.

$--ONZ,a*hh<CR><LF>
|
+--------------------------Station identifier, A-H

Rnn - Routes

Waypoint identifiers, listed in order with starting waypoint first
for route number "nn".

$--Rnn,c--c,c--c----,c--c*hh<CR><LF>
| | |
| | ... +-----------\
| +------------------------/14 field sequence of route waypoint IDs
+-----------------------------nn = Route number

SBK - Loran-C Blink Status
SCY - Loran-C Cycle Lock Status

Loran-C warning flags for Blink (SBK) and Cycle Lock (SCY)
indicating that one or more Loran-C stations being used to
produce Lat/Lon and other navigation data are unreliable.

The use of $--GLC is recommended.

$--SBK,A*hh<CR><LF>
$--SCY,A*hh<CR><LF>
|
+--------------------------Warning Flag

SCD - Loran-C ECDs

The use of $--LCD is recommeded.

SDB - Loran-C Signal Strength

Limited utility, no recommended replacement.

$--SDB,x.x*hh<CR><LF>
|
+-------------------------Signal strength, dB

Page I-08
SGD - Position Accuracy Estimate

Estimate of position accuracy based on geometric of
precision (GDOP) and system noise, in feet and nauticl miles.

Limited utility, no recommended replacement.

SGR - Loran-C Chain Identifier

The unique Loran-C Chain identifier, representing Group Repeti-
tion Interval (GRI) in tens of microseconds (Group Repetition
Interval = [Chain ID]*10, microseconds).

The use of $--GLC is recommended.

$--SGR,xxxx*hh<CR><LF>
|
+-------------------------GRI, tens of microseconds

SIU - Loran-C Stations in Use

The use of $--GLC is recommended.

$--SIU,1,2,3,4,5,6,7,8*hh<CR><LF>
| |
| ... +-----------\
+-------------------------/Stations in use, null fields for stations not in use

SLC - Loran-C Status

Blink, Cycle and SNR warning status and SNR value for all
stations. Stations used in Lat/Lon conversion are identified.

The use of $--GLC and/or $--LCD is recommended.

$--SLC,A,A,A,xxx,A,A,A,A,xxx,...
| | | | | | | | |
| | | | | | | | +------\SNR value, 000 to 999 , Secondary #1
| | | | | | | +---------|Status: SNR Warning Flag, Secondary #1
| | | | | | +-----------|Status: Cycle Lock Warning Flag, Secondary #1
| | | | | +-------------|Status: Blink Warning Flag, Secondary #1
| | | | +---------------/Status: Secondary #1 used in Lat/lon calculation
| | | +-------------------SNR value, 000 to 999 , Master
| | +----------------------Status: SNR Warning Flag, Master
| +------------------------Status: Cycle Lock Warning Flag, Master
+--------------------------Status: Blink Warning Flag, Master

A,A,A,A,xxx,A,A,A,A,xxx,...
| | | | | | | | | |
| | | | | | | | | +--------\
| | | | | | | | +-----------|
| | | | | | | +-------------|Secondary #3
| | | | | | +---------------|
| | | | | +-----------------/
| | | | +--------------------\
| | | +-----------------------|
| | +-------------------------|Secondary #2
| +---------------------------|
+-----------------------------/

A,A,A,A,xxx,A,A,A,A,xxx*hh<CR><LF>
| | | | | | | | | |
| | | | | | | | | +--------\
| | | | | | | | +-----------|
| | | | | | | +-------------|Secondary #5
| | | | | | +---------------|
| | | | | +-----------------/
| | | | +--------------------\
| | | +-----------------------|
| | +-------------------------|Secondary #4
| +---------------------------|
+-----------------------------/

SNC - Navigation Calculation Basis

Basis for navigation calculations, Great Circle or Rhumb Line.

Limited utility, no recommended replacement.

$--SNC,a*hh<CR><LF>
|
+--------------------------Great Circle or Rhumb Line, G/R

Page I-09
SNU - Loran-C SNR Status

Loran-C warning flag for Signal-To-Noise-Ratio indicating that
one or more Loran-C stations being used to produce Lat/Lon and
other navigation data are unreliable.

The use of $--GLC is recommended.

$--SNU,A*hh<CR><LF>
|
+--------------------------Warning Flag

SPS - Loran-C Predicted Signal Strength

Limited utility, no recommended replacement.

$--SPS,xx*hh<CR><LF>
|
+--------------------------Signal strength, dB

SSF - Position Correction Offset

Amount of offset, and direction of offset, applied to measured
position Lat/Lon to produce a displayed position Lat/Lon.

Limited utility, no recommended replacement.

$--SSF,x.x,a,x.x,a*hh<CR><LF>
| | | |
| | | +---------------\E/W East or West
| | +------------------/Longitude offset, minutes
| +---------------------\N/S North or South
+------------------------/Latitude offset, minutes

STC - Time Constant

Time constant specified manually for use in navigation calcula-
tions.

Limited utility, no recommended replacement.

$--STC,xxx*hh<CR><LF>
|
+-------------------------Time constant, 000 to 999 seconds

STR - Tracking Reference

Transmitted prior to a sentence containing velocity-based data
to indicate when velocity is measured over-the-ground or rela-
tive to the water.

The use of appropriate ground or water-referenced approved
sentences such as $--VBW, $--VHW or $--VTG is recommended.

$--STR,a*hh<CR><LF>
|
+--------------------------A = Ground reference, V = Water reference

SYS - Hybrid System Configuration

Limited utility, no recommended replacement.

$--SYS,L,O,T,G,D*hh<CR><LF>
| | | | |
| | | | +------------------DECCA \
| | | +--------------------GPS \
| | +----------------------TRANSIT Null fields for systems not in use
| +------------------------OMEGA /
+--------------------------LORAN-C /

Page I-10
TEC - TRANSIT Satellite Error & Doppler Count

The use of $--TRF is recommended.

$--TEC,A,A,A*hh<CR><LF>
| | |
| | +----------------------Status: Iteration number
| +------------------------Status: Doppler count
+--------------------------Status: Maximum angle

TEP - TRANSIT Satellite Predicted Elevation

Limited utility, no recommended replacement.

$--TEP,x.x,D*hh<CR><LF>
| |
| +---------------------\degrees
+------------------------/Elevation

TGA - TRANSIT Satellite Antenna & Geoidal Heigths

Limited utility, no recommended replacement.

TIF - TRANSIT Satellite Initial Flag

Limited utility, no recommended replacement.

$--TIF,a*hh<CR><LF>
|
+--------------------------Normal operation = A
Set initialization data = V
Initialization data complete = J

TRP - TRANSIT Satellite Predicted Direction of Rise

Limited utility, no recommended replacement.

$--TRP,aa*hh<CR><LF>
|
+--------------------------Southeasterly = SE, southwesterly = SW

TRS - TRANSIT Satellite Operating Status

Limited utility, no recommended replacement.

$--TRS,a*hh<CR><LF>
|
+--------------------------Acquiring = A
Calculating = c
Error = e
Message = m
Test = T
Dead reckoning = U

Page I-11
VCD - Current at Selected Depth

Limited utility, no recommended replacement.

VPE - Speed, Dead Reckoned Parallel to True Wind

Limited utility, no recommended replacement.

$--VPE,x.x,N,x.x,M*hh<CR><LF>
| | | |
| | | +---------------\meters/second
| | +------------------/Speed, "-" = downwind
| +---------------------\knots
+------------------------/Speed, "-" = downwind

VTA - Actual Track

Limited utility, possible use of $--VTG for a portion of the data.

VTI - Intended Track

Limited utility, no recommended replacement.

VWE - Wind Track Efficiency

Limited utility, no recommended replacement.

$--VWE,x.x*hh<CR><LF>
|
+-------------------------Efficiency, percent

VWR - Relative (Apparent) Wind Speed and Angle

Wind angle in relation to the vessel's heading and wind speed meas-
ured relative to the moving vessel.

The use of $--MWV is recommended.

Page I-12
VWT - True Wind Speed and Angle

True wind angle in relation to the vessel's heading and true wind
speed referenced to the water. True wind is the vector sum of the
Relative (Apparent) wind vector and the vessel's velocity vector
relative to the water along the heading line of the vessel. It
represents the wind at the vessel if it were stationary relative to
the water and heading in the same direction.

The use of $--MWV is recommended.

WDC - Distance & Waypoint

Distance from present position to the specified waypoint.

The use of $--BWC is recommended.

$--WDC,x.x,N,c--c*hh<CR><LF>
| | |
| | +-------------------Waypoint identifier
| +---------------------\nautical miles
+------------------------/Distance

WDR - Waypoint Distance, Rhumb Line

The use of $--WDC using great circle calculations is recommend-
ed.

$--WDR,x.x,N,c--c*hh<CR><LF>
| | |
| | +-------------------Waypoint identifier
| +---------------------\nautical miles
+------------------------/Distance

WFM - Route Following Mode

Limited utility, no recommended replacement.

$--WFM,a*hh<CR><LF>
|
+--------------------------Mode: "A" = automatic, "V" = manual

WNR - Waypoint-to-Waypoint Distance, Rhumb Line

The use of $--WNC using great circle calculations is recommend-
ed.

$--WNR,x.x,N,x.x,K,c--c,c--c*hh<CR><LF>
| | | | | |
| | | | | +--------
| | | | +-------------
| | | +---------------\
| | +------------------/
| +---------------------\
+------------------------/

Page I-13
YWP - Water Propagation Speed

Limited utility, no recommended replacement.

YWS - Water Profile

Limited utility, no recommended replacement.

Zaa - Time, Elapsed/Estimated

Elapsed time from point-of-interest.
The use of $--ZFO is recommended.

$--ZFI,hhmmss.ss,hhmmss.ss,c--c*hh<CR><LF>
| | |
| | +-----Waypoint ID
| +--------------Elapsed time from waypoint
+------------------------UTC

Arrival time at point-of-interest.
The use of $--ZTG is recommended.

$--ZPI,hhmmss.ss,hhmmss.ss,c--c*hh<CR><LF>
| | |
| | +-----Waypoint ID
| +--------------Arrival time at waypoint
+------------------------UTC

Estimated time of arrival at waypoint.
The use of $--ZTG is recommended.

$--ZTA,hhmmss.ss,hhmmss.ss,c--c*hh<CR><LF>
| | |
| | +-----Waypoint ID
| +--------------Estimated time at waypoint
+------------------------UTC

Estimated time to event/point-of-interest.
The use of $--ZTG is recommended.

$--ZTE,hhmmss.ss,hhmmss.ss,c--c*hh<CR><LF>
$--ZTI,hhmmss.ss,hhmmss.ss,c--c*hh<CR><LF>
| | |
| | +-----Waypoint ID
| +--------------Estimated time-to-go to waypoint
+------------------------UTC

Arrival time at waypoint.
The use of $--ZTG is recommended.

$--ZWP,hhmmss.ss,hhmmss.ss,c--c*hh<CR><LF>
| | |
| | +-----Waypoint ID
| +--------------Arrival time at waypoint
+------------------------UTC

Page I-14
ZCD - Timer

Limited utility, no recommended replacement.

ZEV - Event Timer

Limited utility, no recommended replacement.

ZLZ - Time of Day

Time of day in hours-minutes-seconds, both with respect to
(UTC) and the local time zone.

The use of $--ZDA is recommended.

$--ZEV,hhmmss.ss,hhmmss.ss,xx*hh<CR><LF>
| | |
| | +------Local zone description [1], -12 to +12
| +--------------Local time
+------------------------UTC

Notes:

[1] Zone description is the number of whole hours added to local
time to obtain GMT, Zone description is negative for East
longitudes.

ZZU - Time, UTC

The use of $--ZDA is recommended.

$--ZZU,hhmmss.ss*hh<CR><LF>
|
+------------------------UTC

End of Appendix I

Page I-15

NMEA 0183 APPENDIX II

Version 2.00

January 1, 1992

IMO List of Equipment and Notes

(To Be Determined)

Page II-1
NMEA 0183 APPENDIX III

Version 2.00

January 1, 1992

Manufacturer's Mnemonic Codes

AAR ASIAN AMERICAN RESOURCES
ACE AUTO-COMM ENGINEERING CORP.
ACR ACR ELECTRONICS, INC.
ACS ARCO SOLAR, INC.
ACT ADVANCED CONTROL TECHNOLOGY
AGI AIRGUIDE INSTRUMENT CO.
AHA AUTOHELM OF AMERICA
AIP AIPHONE CORP.
ALD ALDEN ELECTRONICS, INC.
AMR AMR SYSTEMS
AMT AIRMAR TECHNOLOGY
ANS ANTENNA SPECIALISTS
ANX ANALYTYXS ELECTRONIC SYSTEMS
ANZ ANSCHUTZ OF AMERICA
APC APELCO
APN AMERICAN PIONEER, INC.
APX AMPEREX, INC.
AQC AQUA-CHEM, INC.
AQD AQUADYNAMICS, INC.
AQM AQUA METER INSTRUMENT CO.
ASP AMERICAN SOLAR POWER
ATE AETNA ENGENEERING
ATM ATLANTIC MARKETING COMPANY, INC.
ATR AIRTRON
ATV ACTIVATION, INC.
AVN ADVANCED NAVIGATION, INC.
AWA AWA NEW ZEALAND, LTD.

BBL BBL INDUSTRIES, INC.
BBR BBR AND ASSOCIATES
BDV BRISSON DEVELOPMENT, INC.
BEC BOAT ELECTRIC CO.
BGS BARRINGER GEOSERVICE
BGT BROOKES AND GATEHOUSE, INC.
BHE BH ELECTRONICS
BHR BAHR TECHNOLOGIES, INC.
BLB BAY LABORATORIES
BMC BMC
BME BARTEL MARINE ELECTRONICS

Page III-1
BNI NEIL BROWN INSTRUMENT SYSTEMS
BNS BOWDITCH NAVIGATION SYSTEMS
BRM MEL BARR COMPANY
BRY BYRD INDUSTRIES
BTH BENTHOS, INC.
BTK BALTEK CORP.
BTS BOAT SENTRY, INC.
BXA BENDIX-AVALEX, INC.

CAT CATEL
CBN CYBERNET MARINE PRODUCTS
CCA COPAL CORPORATION OF AMERICA
CCC COASTEL COMMUNICATIONS COMPANY
CCL COASTAL CLIMATE COMPANY
CCM COASTAL COMMUNICATIONS
CDC CORDIC COMPANY
CEC CECO COMMUNICATIONS, INC.
CHI CHARLES INDUSTRIES, LTD.
CKM CINKEL MARINE ELECTRONICS INDUSTRIES
CMA SOCIETE NOUVELLE D'EQUIPEMENT DU CALVADOS
CMC COE MANUFACTURING CO.
CME CUSHMAN ELECTRONICS, INC.
CMP C-MAP, s.r.l.
CMS COASTAL MARINE SALES COMPANY
CMV COURSEMASTER USA, INC.
CNV COASTAL NAVIGATOR
CNX CYNEX MANUFACTURING COMPANY
CPL COMPUTROL, INC.
CPN COMPUNAV
CPS COLUMBUS POSITIONING, LTD.
CPT CPT, INC.
CRE CRYSTAL ELECTRONICS, LTD.
CRO THE CARO GROUP
CRY CRYSTEK CRYSTALS CORP.
CSM COMSAT MARITIME SERVICES
CST CAST, INC.
CSV COMBINED SERVICES
CTA CURRENT ALTERNATIVES
CTB CETEC BENMAR
CTC CELL-TECH COMMUNICATIONS
CTE CASTLE ELECTRONICS
CTL C-TECH, LTD.
CNI CONTINENTAL INSTRUMENTS
CWD CUBIC WESTERN DATA
CWV CELWACE R.F., INC.
CYZ CYZ, INC.

DCC DOLPHIN COMPONENTS CORP.
DEB DEBEG GMBH
DFI DEFENDER INDUSTRIES, INC.
DGC DIGICOURSE, INC.
DME DIGITAL MARINE ELECTRONICS CORP.
DMI DATAMARINE INTERNATIONAL, INC.

Page III-2
DNS DORNIER SYSTEM GMBH
DNT DEL NORTE TECHNOLOGY, INC.
DPS DANAPLUS, INC.
DRL R.L.DRAKE COMPANY
DSC DYNASCAN CORP.
DYN DYNAMOTE CORPORATION
DYT DYTEK LABORATORIES, INC.

EBC EMERGENCY BEACON CORP.
ECT ECHOTEC, INC.
EEV EEV, INC.
EFC EFCOM COMMUNICATION SYSTEMS
ELD ELECTRONIC DEVICES, INC.
EMC ELECTRIC MOTION COMPANY
EMS ELECTRO MARINE SYSTEMS, INC.
ENA ENERGY ANALYSTS, INC.
ENC ENCRON, INC.
EPM EPSCO MARINE
EPT EASTPRINT, INC.
ERC THE ERICSSON CORPORATION
ESA EUROPEAN SPACE AGENCY

FDN FLUIDDYNE
FHE FISH HAWK ELECTRONICS
FJN JON FLUKE CO.
FMM FIRST MATE MARINE AUTOPILOTS
FNT FRANKLIN NET AND TWINE, LTD.
FRC THE FREDERICKS COMPANY
FTG T.G.FARIA CORPORATION
FUJ FUJITSU TEN CORPORATION OF AMERICA
FEC FURUNO ELECTRIC CO.
FUR FURUNO, USA. INC.

GAM GRE AMERICA, INC.
GCA GULF CELLULAR ASSOCIATES
GES GEOSTAR CORPORATION
GFC GRAPHIC CONTROLS, CORP.
GIS GALAX INTEGRATED SYSTEMS
GPI GLOBAL POSITIONING INSTRUMENT CORP.
GRM GARMIN CORPORATION
GSC GOLD STAR COMPANY, LTD.
GTO GRO ELECTRONICS
GVE GUEST CORPORATION
GVT GREAT VALLEY TECHNOLOGY

HAL HAL COMMUNICATIONS CORPORATION
HAR HARRIS CORPORATION
HIG HY-GAIN
HIT HI-TEC
HPK HEWLETT-PACKARD
HRC HARCO MANUFACTURING COMPANY
HRT HART SYSTEMS, INC.
HTI HEART INTERFACE, INC.

Page III-3
HUL HULL ELECTRONICS COMPANY
HWM HONEYWELL MARINE SYSTEMS

ICO ICOM OF AMERICA, INC.
IFD INTERNATIONAL FISHING DEVICES
IFI INSTRUMENTS FOR INDUSTRY
IME IMPERIAL MARINE EQUIPMENT
IMI I.M.I.
IMM ITT MACKAY MARINE
IMP IMPULSE MANUFACTURING, INC.
IMT INTERNATIONAL MARKETING AND TRADING, INC.
INM INMAR ELECTRONIC AND SALES, INC.
INT INTECH, INC.
IRT INTERA TECHNOLOGIES, LTD.
IST INNERSPACE TECHNOLOGY, INC.
ITM INTERMARINE ELECTRONICS, INC.
ITR ITERA, LTD.

JAN JAN CRYSTALS
JFR RAY JEFFERSON
JMT JAPAN MARINE TELECOMMUNICATIONS
JRC JAPAN RADIO COMPANY, LTD.
JRI J-R INDUSTRIES, INC.
JTC J-TECH ASSOCIATES, INC.
JTR JOTRON RADIOSEARCH, LTD.

KBE KB ELECTRONICS, LTD.
KBM KENNEBEC MARINE COMPANY
KLA KLEIN ASSOCIATES, INC.
KMR KING MARINE RADIO CORP.
KNG KING RADIO CORPORATION
KOD KODEN ELECTRONICS COMPANY, LTD.
KRP KRUPP INTERNATIONAL, INC.
KVH KVH COMPANY
KYI KYOCERA INTERNATIONAL, INC.

LAT LATITUDE CORPORATION
LEC LORAIN ELECTRONICS CORP.
LMM LAMARCHE MANUFACTURING CO.
LRD LORAD
LSE LITTLEMORE SCIENTIFIC ENGINEERING
LSP LASER PLOT, INC.
LTF LITTLEFUSE, INC.
LWR LOWRANCE ELECTRONICS CORP.

MCL MICROLOGIC, INC.
MDL MEDALLION INSTRUMENTS, INC.
MEC MARINE ENGINE CENTER, INC.
MEG MARITEC ENGINEERING GMBH
MFR MODERN PRODUCTS, LTD.
MFW FRANK W. MURPHY MANUFACTURING
MGS MG ELECTRONIC SALES CORP.
MIE MIECO, INC.

Page III-4
MIM MARCONI INTERNATIONAL MARINE CO.
MLE MARTHA LAKE ELECTRONICS
MLN MATLIN COMPANY
MLP MARLIN PRODUCTS
MLT MILLER TECHNOLOGIES
MMB MARSH-MCBIRNEY, INC.
MME MARKS MARINE ENGINEERING
MMP METAL MARINE PILOT, INC.
MMS MARS MARINE SYSTEMS
MNI MICRO-NOW INSTRUMENT COMPANY
MNT MARINE TECHNOLOGY
MNX MARINEX
MOT MOTOROLA COMMUNICATIONS AND ELECTRONICS
MPN MEMPHIS NET AND TWINE COMPANY, INC.
MQS MARQUIS INDUSTRIES, INC.
MRC MARINECOMP, INC.
MRE MORAD ELECTRONICS CORP.
MRP MOORING PRODUCTS OF NEW ZEALAND
MRR II MORROW, INC.
MRS MARINE RADIO SERVICE
MSB MITSUBISHI ELECTRIC COMPANY, LTD.
MSE MASTER ELECTRONICS
MSM MASTER MARINER, INC.
MST MESOTECH SYSTEMS, LTD.
MTA MARINE TECHNICAL ASSOCIATES
MTG MARINE TECHNICAL ASSISTANCE GROUP
MTK MARTECH, INC.
MTR MITRE CORPORATION, THE
MTS METS, INC.
MUR MURATA ERIE NORTH AMERICA
MVX MAGNAVOX ADVANCED PRODUCTS AND SYSTEMS CO.
MXX MAXXIMA MARINE
MES MARINE ELECTRONICS SERV. INC.

NAT NAUTECH, LTD.
NEF NEW ENGLAND FISHING GEAR, INC.
NMR NEWMAR
NGS NAVIGATION SCIENCES, INC.
NOM NAV-COM, INC.
NOV NOVATEL COMMUNICATIONS, LTD.
NSM NORTHSTAR MARINE
NTK NOVATECH DESIGNS, LTD.
NVC NAVICO
NVS NAVSTAR
NVO NAVIONICS, S.P.A.

OAR O.A.R. CORPORATION
ODE OCEAN DATA EQUIPMENT CORP.
ODN ODIN ELECTRONICS, INC.
OIN OCEAN INSTRUMENTS, INC.
OKI OKI ELECTRIC INDUSTRY COMPANY
OLY NAVSTAR LTD. (POLYTECHNIC ELECTRONICS)
OMN OMNETICS

Page III-5
ORE OCEAN RESEARCH
OTK OCEAN TECHNOLOGY

PCE PACE
PDM PRODELCO MARINE SYSTEMS
PLA PLATH, C. DIV OF LITTON
PLI PILOT INSTRUMENTS
PMI PERNICKA MARINE INSTRUMENTS
PMP PACIFIC MARINE PRODUCTS
PRK PERKO, INC.
PSM PEARCE-SIMPSON
PTC PETRO-COM
PTG P.T.I./GUEST
PTH PATHCOM, INC.

RAC RACAL MARINE, INC.
RAE RCA ASTRO-ELECTRONICS
RAY RAYTHEON MARINE COMPANY
RCA RCA SERVICE COMPANY
RCH ROACH ENGINEERING
RCI ROCHESTER INSTRUMENTS, INC.
RDI RADAR DEVICES
RDM RAY-DAR MANUFACTURING COMPANY
REC ROSS ENGINEERING CO.
RFP ROLFITE PRODUCTS, INC.
RGC RCA GLOBAL COMMUNICATIONS, INC.
RGY REGENCY ELECTRONICS, INC.
RMR RCA MISSILE AND SURFACE RADAR
RSL ROSS LABORATORIES, INC.
RSM ROBERTSON-SHIPMATE, USA.
RWI ROCKWELL INTERNATIONAL
RME RACAL MARINE ELECTRONICS
RTN ROBERTSON TRITECH NYASKAIEN A/S

SAI SAI, INC.
SBR SEA-BIRD ELECTRONICS, INC.
SCR SIGNALCRAFTERS, INC.
SEA SEA
SEC SERCEL ELECTRONICS OF CANADA
SEP STEEL AND ENGINE PRODUCTS, LTD.
SFN SEAFARER NAVIGATION INTERNATIONAL, LTD.
SGC SGC, INC.
SIG SIGNET, INC.
SIM SIMRAD, INC.
SKA SKANTEK CORPORATION
SKP SKIPPER ELECTRONICS A/S
SME SHAKESPEARE MARINE ELECTRONICS
SMF SEATTLE MARINE AND FISHING SUPPLY CO.
SML SIMERL INSTRUMENTS
SMI SPERRY MARINE, INC.
SNV STARNAV CORPORATION
SOM SOUND MARINE ELECTRONICS, INC.
SOV SELL OVERSEAS AMERICA

Page III-6
SPL SPELMAR
SPT SOUND POWERED TELEPHONE
SRD SRD LABS
SRS SCIENTIFIC RADIO SYSTEMS, INC.
SRT STANDARD RADIO AND TELEFON AB
SSI SEA SCOUT INDUSTRIES
STC STANDARD COMMUNICATIONS
STI SEA-TEMP INSTRUMENT CORP.
STM SI-TEX MARINE ELECTRONICS
SVY SAVOY ELECTRONICS
SWI SWOFFER MARINE INSTRUMENTS, INC.
SRS SHIPMATE, RAUFF & SORENSEN, A/S

TBB THOMPSON BROTHERS BOAT MANUFACTURING CO.
TCN TRADE COMMISSION OF NORWAY, THE
TDL TIDELAND SIGNAL
THR THRANE AND THRANE A/A
TLS TELESYSTEMS
TMT TAMTECH, LTD.
TNL TRIMBLE NAVIGATION
TRC TRACTOR, INC.
TSI TECHSONIC INDUSTRIES, INC.
TTK TALON TECHNOLOGY CORPORATION
TTS TRANSTECTOR SYSTEMS
TWC TRANSWORLD COMMUNICATIONS, INC.
TXI TEXAS INSTRUMENTS, INC.

UME UMEC
UNI UNIDEN CORPORATION OF AMERICA
UNP UNIPAS, INC.
UNF UNIFORCE ELECTRONICS COMPANY

VAN VANNER, INC.
VAR VARIAN EIMAC ASSOCIATES
VCM VIDEOCOM
VEX VEXILAR
VIS VESSEL INFORMATION SYSTEMS, INC.
VMR VAST MARKETING CORP.

WAL WALPORT U.S.A.
WBG WESTBERG MANUFACTURING, INC.
WBR WESBAR CORPORATION
WEC WESTINGHOUSE ELECTRIC CORP.
WHA W-H AUTOPILOTS
WMM WAIT MANUFACTURING AND MARINE SALES CO.
WMR WESMAR ELECTRONICS
WNG WINEGARD COMPANY
WSE WILSON ELECTRONICS CORPORATION
WTC WATERCOM
WST WEST ELECTRONICS LIMITED

YAS YAESU ELECTRONICS

Page III-7

NMEA 0183 APPENDIX IV

Version 2.00

January 1, 1992

GLOSSARY

accuracy - in navigation, a measure of the error between the
point desired and the point achieved, or between the position in-
dicated by measurement and the true position [compare with preci-
sion].

address field - for sentences in this standard, the fixed length
field following the beginning sentence delimiter "$" (HEX 24).
For approved sentences, composed of a two character talker iden-
tifier and a three character sentence formatter. For proprietary
sentences, composed of the charcter "P" (HEX 50) followed by a
three character manufacturer identification code.

additional secondary factor - in Loran-C, a correction in addi-
tion to the secondary phase factor correction for the additional
time (or phase delay) for transmission of a low frequency signal
over a composite land-seawater path when the signal transit time
is based on the free-space velocity.

apparent wind - (see 'relative wind').

approved sentence - a sentence which has been approved for gener-
al use by the NMEA general assembly and is listed in this stand-
ard and attached Appendices.

arrival alarm - an alarm signal issued by a voyage tracking unit
which indicates arrival at or at a pre-determined distance from a
waypoint. - (see 'arrival circle')

arrival circle - an artificial boundary placed around the desti-
nation waypoint of the present navigation leg, the entering of
which will signal an arrival alarm.

arrival perpendicular - crossing of the line which is perpendicu-
lar to the course line and which passes through the destination
waypoint.

azimuth - the horizontal direction of a celestial point from a
terrestrial point, expressed as the angular distance from a ref-
erence direction, usually measured from 000deg at the reference di-
rection clockwise through 360deg.

Page IV-1
ASCII - American Standard Code for Information Interchange. A 7
bit wide serial code describing numbers, upper and lower case al-
pha, characters, special and non-printing charcters. See Ameri-
can National Standards Institute documents ANSI X 3.15, ANSI X
3.16 and ANSI X 3.4.

atomic time - time obtained by counting the cycles of a signal in
resonance with certain kinds of atoms.

autopilot - an automatic device for steering a vessel so as to
maintain its heading in an intended direction. Mechanical means
are used to steer the rudder. A radio navigation system is often
connected to correct for track errors, or to select new destina-
tions.

bearing - the horizontal direction of one terrestrial point from
another, expressed as the angular distance from a reference di-
rection, usually measured from 000deg at the reference direction
clockwise through 360deg.

Beaufort wind scale - a numerical scale for indicating wind
speed. Beaufort numbers (or forces) range from force 0 (calm) to
force 12 (hurricane).

blink - in Loran-C, a signal used to indicate that a station is
malfunctioning. Intended to prevent use of that signal for navi-
gation.

checksum - for this standard, a validity check performed on the
data contained in the sentence, calculated by the talker, ap-
pended to the message, when recalculated by the listener for com-
parison to determine if the message was received correctly. Re-
quired for some sentences, optional for all others.

communication protocoll - a method established for message trans-
fer between a talker and a listener which includes the message
format and the sequence in which the message are to be trans-
ferred. Also includes the signaling requirements such as baud
rate, stop bits, parity, and bits per character.

course - the horizontal direction in which a vessel is steered or
intended to be steered, expressed as angular distance from north,
usually from 000deg at north, clockwise through 360deg. Strictly,
the term applies to direction through the water, not the direc-
tion intended to be made good over the ground (see 'track'). Dif-
fers from heading.

course over ground (COG) - term used to refer to the direction of
the path over ground actually followed by a vessel [a misnomer in
that courses are directions steered or intended to be steered
through the water with respect to a reference meridian].

cross track error (XTE) - the distance from the vessel's present
position to the closest point on a line between the origin and
destination waypoints of the navigation leg being travelled.

Page IV-2
cycle lock - in Loran-C, the comparison, in time difference, be-
tween corresponding carrier cycles contained in the rise times of
a master and slave station pulse is called cycle match. This
value when refined to a determination of the phase difference be-
tween these two cycles results in cycle lock. (See also 'en-
velope-to-cycle distortion').

data field - in an NMEA 0183 sentence, a field which contains a
data value.

dead reckoning - the process of determining the position of a
vessel at any instant by applying to the last well-determined po-
sition (point of departure or subsequent fix) the run that has
since been made, usually based on the recent history of speed and
heading measurements.

Decca chain - a group of associated stations of the Decca Naviga-
tor System. A Decca chain normally consists of a master and
three slave stations. Each slave station is called by the color
of associated pattern of hyperbolic lines as printed on the
chart, i.e., red slave, green slave, purple slave.

Decca Navigator System - a short to medium range low frequency
(70-130 kHz) radionavigation system by which a hyperbolic line of
position of high accuracy is obtained. The system is an arrange-
ment of fixed, phase locked, continuous wave transmitters operat-
ing on harmonically related frequencies and special receiving
equipment located on a vessel.

delimiter - in this standard, a character or characters used to
separate fields or sentences. The following delimiters are used
in this standard:

field delimiters - ASCII "$" (HEX 24) for address fields
- ASCII "," (HEX 2C) for data fields
- ASCII "*" (HEX 2A) for checksum field

sentence delimiters - carriage return <CR> and line feed
<LF> (HEX 0D0A)
[note: a <CR><LF> is not required preceding the first
sentence transmitted]

depth sounder - an instrument which determines the depth of water
by measuring the time interval between the emissions of a sound
and the return of its echo from the bottom.

destination - the immediate geographic point of interest to
which a vessel is navigating. It may be the next waypoint along
a route of waypoints or the final destination of a voyage.

deviation - the angle between the magnetic meridian and the axis
of a compass card, expressed in degrees east or west to indicate
direction in which the northern end of the compass card is offset
from magnetic north.

Page IV-3
Doppler speed log - an instrument which measures the relative mo-
tion between a vessel and the reflective sea bottom (for bottom
return mode) or suspended particulate matter in the seawater it-
self (for water return mode) by measuring the frequency shifts
between a transmitted and subsequently echoed acoustic or elec-
tromagnetic signal.

drift - the speed of a current.

echo sounder - (see 'depth sounder').

envelope-to-cycle distortion (ECD) - the time relationship be-
tween the phase of the Loran-C carrier and the time origin of the
envelope waveform.

field - in this standard, a character or string of characters im-
mediately preceded by a field delimiter (see 'delimiters').

fixed field - in this standard, a field in which the number of
characters is fixed. For data fields, such fields are shown in
the sentence definitions with no decimal point. Other fields
which fall into this category are the address field and the
checksum field (if present).

geoid - a surface along whith the gravity potential is everywhere
equal (equipotential surface) and to which the direction of
gravity is always perpendicular.

geometric dilution of precision (GDOP) - a value representing all
geometric factors that degrade the accuracy of a position fix
which has been derived from a navigation system.

Global Positioning System (GPS) - (full name NAVSTAR Global Posi-
tioning System) an all-weather, continuous satellite navigation
system being developed by the Department of Defense under Air
Force management. The fully deployed operational system is in-
tended to provide highly accurate position and velocity informa-
tion in three dimensions and precise time and time interval on a
global basis, to an unlimited number of authorized users. Al-
though developed primarily for military missions, current policy
calls for civil availability with a degradation in system accura-
cy in order to protect U.S. national security interests.

great circle - the intersection of the surface of a sphere and a
plane through its center.

great circle chart - a chart on which a great circle appears as a
straight line or approximately so.

great circle direction - horizontal direction of a great circle,
expressed as angular distance from a reference direction.

group repetition interval (GRI) - of a particular Loran-C chain,
the specified time interval for all stations of the chain to
transmit their pulse groups. For each chain a minimum group

Page IV-4
repetition interval is selected of sufficient duration to provide
time for each station to transmit its pulse group and additional
time between each pulse group so that signals from two or more
stations cannot overlap in time anywhere within the coverage
area.

gyrocompass - a compass having one or more gyroscopes as the di-
rective element, and which is north-seeking. Its operation de-
pends upon four natural phenomena: gyroscopic inertia, gyroscop-
ic precession, the earth's rotation, and gravity.

gyropilot - an automatic device for steering a vessel by means of
control signals received from gyrocompass (see 'autopilot').

gyroscope - a rapidly rotating mass free to move about one or
both axes perpendicular to the axis of rotation and to each oth-
er.

heading - the horizontal direction in which a ship actually
points or heads at any instant, expressed in angular units from a
reference direction, usually from 000deg at the reference direction
clockwise through 360deg. (See 'true heading' and 'magnetic heading')

heading-to-steer - the difference between the bearing to destina-
tion (from present position) and track-made-good, applied to the
bearing to the destination to produce a heading that will guide
the vessel to the destination.

horizontal dilution of precision (HDOP) - similar to GDOP, except
elevation factors are ignored.

keel - a longitudinal timber or plate extending along the center
of the bottom of a ship and often projecting from the bottom.

line of position (LOP) - in Loran or Decca navigation systems, a
vector obtained by measurement of the time difference between the
receipt of the master and slave signals which is then used to se-
lected a corresponding LOP from a chart or table, Two or more
intersecting LOP's are required to obtain a position fix.

listener - in this standard, the recipient of message across
the interconnecting link.

log - an instrument for measuring the speed or distance or both
traveled by a vessel.

Loran - the general designation of one group of radionavigation
systems by which a hyperbolic line of position is determined
through measuring the difference in the times of reception of
synchronized pulse signals from two fixed transmitters.

magnetic bearing - bearing relative to magnetic north; compass
bearing corrected for deviation.

Page IV-5
magnetic heading - heading relative to magnetic north.

manufacturer identification code - in this standard, a three
character manufacturer identifier, usually an acronym derived
from the company name, which has been approved and is listed in
Appendix III, for use by a manufacturer as part of the address
field in formulation of proprietary sentences.

Mercator map projection - a conformal cylindrical map projection
in which the surface of a sphere or spheroid, such as earth, is
conceived as developed on a cylinder tangent along the equator.
Meridias appear as equally spaced vertical lines and parallels
as horizontal lines drawn farther apart as the latitude and
longitude scales at any point is maintained. Also known as Mer-
cator map projection.

Navigation Leg - the portion of a voyage upon which the vessel
currently travels. Each leg consists of two waypoints, an ORIGIN,
a DESTINATION, and a line between between them, upon which the vessel
travels.

Navy Navigation Satellite System (TRANSIT) - an operational
satellite navigation system of the united States conceived and
developed by the Applied Physics Laboratory of John Hopkins
University for the U.S. Navy. It is an all-weather, worldwide,
and passive system used primarily for the navigation of surface
ships and submarines. Also known by the acronyms NAVSAT or
TRANSIT, it consists of a constellation of orbiting satellites, a
ground system of tracking stations, and any number of user sta-
tions (navigators). The user stations are radionavigation de-
vices composed of a receiver, a frequency cycle-counter, and a
computer. The minimum constellation for system operation is four
satellites (five satellites in orbit provide redundancy). The
satellite orbits are controlled by the tracking stations. Satel-
lites broadcast current known positions while orbiting the earth.
The NAVSAT system utilizes the Doppler shift of radio signals
transmitted from the satellite to measure the relative velocity
between the satellite and the navigator. Knowing the satellite
orbit precisely, the navigator's absolute position can be accu-
rately determined from this time rate of change of range to the
satellite.

null field - in this standard, indicates that data is not avail-
able for the field. Indicated by two ASCII commas, i.e., ",,"
(HEX 2C2C), or, for the last data field in a sentence, one comma
followed by either the checksum delimiter "*" (HEX 2A) or the
sentce delimiters <CR><LF> (HEX 0D0A). [Note: the ASCII Null
character (HEX 00) is not to be used for null fields!]

Omega Navigation System - a worldwide, continuous, radionaviga-
tion system of medium accuracy which provides hyperbolic lines of
position through phase comparisons of VLF (10-14kHz) continuous
wave signals transmitted on a common frequency on a time-shared
basis. The fully implemented system is comprised of only eight
transmitting stations.

Page IV-6
one-way communication protocol - a protocol established between a
talker and a listener in which only the talker may send messages
[compare to 'two-way communication protocol'].

origin waypoint - the starting point of the present navigation
leg.

precision - a measure of how close the outcome of a series of ob-
servations or measurements cluster about some estimated value of
a desired quantity, such as the average value of a series of ob-
servations of a quantity. Precision implies repeatability of
the observations within some specified limit and depends upon the
random errors encountered due to the quality of the observing
equipment, the skill of the observer and randomly fluctuating
conditions such as temperature, pressure, refraction, ect. [com-
pare with 'accuracy'].

proprietary sentence - a sentence to be sent across the intercon-
necting link which is not included in the List of Approved Sen-
tences of this standard. All proprietary sentences sent over the
interconnecting link shall contain a unique talker identifier
which bwgins with a "P" (HEX 50) followed by a three character
manufacturer identification code.

relative bearing - bearing relative to heading or to vessel.

relative wind - the speed and relative direction from which the
wind appears to blow with reference to a moving point (also
called apparent wind).

rhumb line - a line on the surface of the earth making the same
oblique angle with allmeridians. A rhumb line is a straight
line on a rhumb (or Mercator) projection.

rhumb direction - the horizontal direction of a rhumb line, ex-
pressed as angular distance from a refernce direction. Also
known as Mercator direction. (See Mercator map projection).

RMa sentence - Recommended Minimum Acceptable sentence, a compos-
ite sentence recommended by this standard to insure interopera-
bility between talkers and listeners and to insure that all data
considered necessary for navigation is sent by a particular navi-
gation unit.

route - a planned course of travel, usually composed of more than
one navigation leg.

route system - any system of one or more routes and/or routing
measures aimed at reducing the risk of casualties schemes, rec-
ommended tracks, restricted areas, inshore traffic zones, etc.

semi-fixed field - data fields having a base other than 10, but
use base 10 to express precision of the final term (such as
minutes expressed as units with a decimal trailer instead of sec-

Page IV-7
onds in a base 60 field, or seconds expressed with a decimal
trailer).

selected waypoint - the waypoint currently selected to be the
point toward which the vessel is travelling. Also called "TO"
Waypoint, destination or destination waypoint.

sentence formatter - in this standard, a three charcter sentence
identifier which follows the talker identifier ans is included as
part of the address field. The sentence formatters are an inte-
gral part of the sentence definitions provided by this standard
and attached appendices.

set - the direction towards which a current flows.

speed log - an instrument for measuring a vessel's speed through
water and/or speed over ground. Asingle axis speed log normally
measures speed along the longitudinal (fore/aft) axis of the ves-
sel, while a dual axis speed log measures speed along the trans-
verse (port/starboeard) axis as well. (Also see 'Doppler speed
log').

speed made good - the adjusted speed which takes into account
factors such as drift and wind speed. Can be estimated or comput-
ed ny a navigation receiver.

speed over ground (SOG) - the speed of a vessel along the actual
path of travel over the ground.

signal-to-noise ratio (SNR) - the ratio of the magnitude of a
signal to that of the noise (interference), often expressed in
decibels.

talker - in the NMEA 0183 Standard, the originator of messages
across an NMEA 0183 link.

talker identifier - the first two characters following the "$"
(HEX 24) in an NMEA 0183 sentence (address character 1 and 2);
selected from Table - Talker Identifier, Mnemonics of the NMEA
0183 Standard.

time difference (TD) - in Loran-C, the time difference measured
from the time of reception of the master station signal to the
time of reception of the slave station signal.

track - the intended or desired horizontal direction of travel
with respect to the earth. The track expressed in degrees of the
compass may differ from the course due to allowence made in the
course for such factors as sea and weather conditions in order to
resume the desired track (see 'track made good').

track made good - the single resultant direction from a point of
departure to a point of arrival at any given time.

Page IV-8
transducer - a device that converts one type of energy to anoth-
er, as a loudspeaker that changes electrical energy into acousti-
cal energy.

true bearing - bearing relative to true north; compass bearing
corrected for compass error.

true heading - heading relative to true north.

to-way-communication protocol - a protocol established between a
talker and a listener in which the listener may also issue re-
quests to the talker when required [compare to 'one-way communica-
tion protocol].

UART - Universal Asynchronous Receiver/Transmitter which produces
an electrical signal and timing for transmission of data over a
communication path, and circuitry for detection and capture of
such data transmitted from another UART.

Iniversal Time Coordinated (UTC) - a time scale based on the ro-
tation of the earth which is disseminated by most broadcast time
services [compare with 'atomic time'].

variable field - in NMEA 0183 sentences, a data field which may
or may not contain a decimal point depending on the requirements
and the accuracy of the measuring device (talker).

variation - the angle between the magnetic and geographic merid-
ians at any place, expressed in degrees and minutes east or west
to indicate the direction of magnetic north from true north.

waypoint - a reference point on a track.

End of Appendix IV

Page IV-9

NMEA 0183 Version 2.00

January 1, 1992

Index

AAM - Waypoint Arrival Alarm, 22 BWW - Bearing
Accuracy, IV-1 Waypoint to Waypoint, 24
Additional secondary factor, IV-1
Additions to Approved Sentences, 14 Character Definitions, 15, 16
Address Field, 8, IV-1 Characters, 8, 16
approved sentence, IV-1 Checksum, IV-2
proprietary sentence, IV-1 Checksum delimiter character "*", 10
ALM- GPS Almanac Data, 22 Checksum Field, 10
Alpha data fields, 10 Communication protocol, IV-2
Alphanumeric data fields, 10 Conductor Definitions, 5
American Practical Navigator, 4 Connector, 5
ANSI standards, 3, 7 Course, IV-2
APA Not recommended - Table I-2 Course over ground (COG), IV-2
APB - Autopilot Sentence "B", 23 Cross track error (XTE), IV-2
Apparent wind, IV-1, IV-7 Cycle lock, IV-3
Applications, 39
Approved Address Field, 9 Datat bits, 7
Approved sentence formatters, 18 Data Content, 15
Approved Sentence Structure, 12 Data Field Types, 10
Approved Sentences, 11, IV-1 Data Fields, 9, IV-3
Arrival alarm, IV-1 Data Format Protocol, 8
Arrival circle, IV-1 Data Sentence block, 12
Arrival perpendicular, IV-1 Data transmission, 3, 7
ASCII, 3, IV-2 Data transmission protocol/timing, 1
ASCII NULL character (HEX 00), 10 Date of Update, 4
ASD - Autopilot System Data, 23 DBK Not recommended - Table I-2
Atomic time, IV-2 DBS Not recommended - Table I-2
Autopilot, IV-2 DBT - Depth Below Transducer, 24
Availability and Updates, 2 Dead reckoning, IV-3
Decca Navigator System, IV-3
Baud rate, 7 Defined field, 21
Bearing, IV-2 Definitions, 3
Beaufort wind scale, IV-2 Delimiter, 8, 9, IV-3
BEC - Bearing & Distance field, IV-3
Dead Reckoned, 23 sentence, IV-3
BER Not recommended - Table I-2 Depth sounder, IV-3
Blink, IV-2 Destination, IV-3
BOD - Bearing Deviation, IV-3
Origin to Destination, 24 Differential-receiver, 6
BPI Not recommended - Table I-2 Direction to steer, 37
BWC - Bearing & Distance Doppler speed log, IV-4
to waypoint, 24 DPT - Depth, 25
BWR - Bearing & Distance Drift, IV-4
Rhumb Line, 24 Drive capability, 4

Index Page 1
DRU Not recommended - Table I-2 Heading, IV-5
Heading-to-steer, IV-5
Echo sounder, IV-4 Hexadecimal value, 10
EIA-422-A, 4, 6 High-bandwidth, 3
Electrical Connections, 5 Horizontal dilution of precision, IV-5
Electrical Isolation, 7 HSC - Heading Steering Command, 28
Electrical Signal Characteristics, 5 HVD Not recommended - Table I-2
Envelope-to-cycle distortion, IV-4 HVM Not recommended - Table I-2
Error checking, 3
Example Sentences, 39 ICD-GPS-200, 4
Exclusive OR, 10 Idle, 5
I.E.C., 1, 2, 6
Field Definitions, 17 IMA Not recommended - Table I-2
Field delimiter, 12 I.M.O., 1, 22
Fields, 8, IV-4 Information Fields, 21
File transfer, 3 Input/output circuits, 4
Fixed alpha field, 21 Intended Application and Limitations, 3
Fixed field, IV-4 Interconnecting Wire, 5
Fixed HEX field, 21
Fixed length data fields, 10 Keel, IV-5
Fixed number field, 21
Fixed text field, 21 Latitude, 20
Fixed/variable data fields, 10 LCD - Loran-C Signal Data, 29
FSI Examples, 41 Leading or trailing "zeros", 9
FSI - Frequency Set Information, 25 Line of position (LOP), IV-5
List of sentences, 4
GDa Not recommended - Table I-2 LISTENER, 3, IV-5
General structure of sentences, 10 Listener receive circuits, 6
Geoid, IV-4 Load requirements, 4
Geometric dilution of precision, IV-4 Log, IV-5
GGA - GPS Fix Data, 26 Logical "1", 5
GLa Not recommended - Table I-2 Longitude, 20
GLC - Position - Loran-C, 26 Loran, IV-5
GLL - Position - Lat/Lon, 27 Loran C Arrival Alarm, 39
Global Positioning System (GPS), IV-4 Loran C LAT/LONG, 39
Glossary of terms - Appendix IV, IV-1
GOa Not recommended - Table I-2 Magnetic bearing, IV-5
Great circle, IV-4 Magnetic heading, IV-6
Great circle chart, IV-4 Manufacturer's Documentation, 4
Great circle direction, IV-4 Manufacturer's Mnemonic Code, 9,
Group repetition interval (GRI), IV-4 Appendix II, IV-6
GSA - GPS DOP and Active Satellites, 27 Marking, 5
GSV - GPS Satellites in View, 27 Maximum number of characters, 11
GTD Not recommended - Table I-2 Maximum number of fields, 11
GXa Not recommended - Table I-2 Maximum Voltage, 7
GXA - TRANSIT Position, 28 MDA Not recommended - Table I-2
Gyrocompass, IV-5 Mercator, IV-6
Gyropilot, IV-5 MHU Not recommended - Table I-2
Gyroscope, IV-5 Minimum differential input voltage, 6
Minimum number of fields, 11
Hardware Specification, 5 MMB Not recommended - Table I-2
HCC Not recommended - Table I-2 Most significant bit, 9
HCD Not recommended - Table I-2 MTA Not recommended - Table I-2
HDG - Heading, Deviation / Variation, 28 MTW Not recommended - Table I-2
HDM Not recommended - Table I-2 Multiple listeners, 5
HDT - Heading - True, 28 MWD Not recommended - Table I-2

Index Page 2
MWH Not recommended - Table I-2 RMC - Minimum Specific GPS/TRANSIT, 31
MWS Not recommended - Table I-2 Rnn Not recommended - Table I-2
MWV - Wind Speed and Angle, 29 ROT - Rate Of Turn, 32
Route, IV-7
Navigation Leg, IV-6 Route system, IV-7
Navy Navigation Satellite System, IV-6 RPM - Revolutions, 32
Negative sign, 21 RSA - Rudder Sensor Angle, 32
NMEA 0180, 1 RSD - RADAR System Data, 32
NMEA 0182, 1 RTE - Routes, 33
NMEA address, 2
NMEA Interface Standards Committee, 2 SBK Not recommended - Table I-2
Not recommended - Appendix I SCD Not recommended - Table I-2
Null field, 8, 10, IV-6 Scope, 3
Numeric data fields, 10,21 SCY Not recommended - Table I-2
SDB Not recommended - Table I-2
OLN - Omega Lane Numbers, 29 Selected waypoint, IV-8
OLW Not recommended - Table I-2 Semi-fixed field, IV-7
Omega, IV-6 Sentence elements, 11
OMP Not recommended - Table I-2 Sentence formatter, IV-8
ONZ Not recommended - Table I-2 Sentence terminator, 12
Operator's manuals, 4 Sentence Transmission Timing, 14
Optional Checksum Delimiter, 12 Sentences, 10
Optional Checksum Field, 12 Serial asynchronous, 7
Optoisolator, 6 Set, IV-8
Origin waypoint, IV-7 SFI - Scanning Frequency Information, 33
OSD - Own Ship Data, 30 SGD Not recommended - Table I-2
SGR Not recommended - Table I-2
"P", 9 Shield, 5
Parallel, 5 Ships ground, 7
Parity, 7 Signal State Definitions, 5
Precision, 9, IV-1, IV-7 Signal-to-noise ratio (SNR), IV-8
Preferred sentences, 11 SIU Not recommended - Table I-2
Proprietary, 4 SLC Not recommended - Table I-2
Proprietary Address Field, 9 SNC Not recommended - Table I-2
Proprietary sentence, 13, IV-6, IV-7, SNU Not recommended - Table I-2
example of, 40 Software and hardware revision, 4
Protective circuits, 6 Spaces, 21
Special Format Fields, 20
"Q", 9 Speed log, IV-8
Query Address Field, 9 Speed made good, IV-8
Query Sentences, 13 Speed over ground (SOG), IV-8
SPS Not recommended - Table I-2
Radar, 3 SSF Not recommended - Table I-2
Receiver Diagrams, 42 Standard, 1
References, 3 Status, 20
Relative bearing, IV-7 STC Not recommended - Table I-2
Relative wind, IV-7 STN - Multiple Data ID, 34
Reply To Query Sentence, 13 Stop bit, 5, 7
Reserved Characters, 8, 15 STR Not recommended - Table I-2
Reverse bias, 6 SYS Not recommended - Table I-2
Rhumb direction, IV-7
Rhumb line, IV-7 TABLE 6 FIELD TYPE SUMMARY, 20
RMA Examples, 40 TALKER, 3, IV-8
RMa sentence, IV-7 Talker drive circuits, 6
RMA - Minimum Specific Loran-C Data, 30 Talker identifier, 17, IV-8
RMB - Minimum Navigation Information, 31 TEC Not recommended - Table I-2

Index Page 3
Technical information, 2 XDR - Transducer Measurements, 37
TEP Not recommended - Table I-2 XTE - Cross-Track Error
TGA Not recommended - Table I-2 Measured, 37
TIF Not recommended - Table I-2 XTR - Cross-Track Error
Time, 20 Dead Reckoning, 38
Time difference (TD), IV-8
Track, IV-8 YWP Not recommended - Table I-2
Track errors, IV-2 YWS Not recommended - Table I-2
Track made good, IV-8
Transducer, IV-9 Zaa Not recommended - Table I-2
TRF - TRANSIT Fix Data, 34 ZCD Not recommended - Table I-2
TRP Not recommended - Table I-2 ZDA - Time & Date, 38
TRS Not recommended - Table I-2 ZEV Not recommended - Table I-2
True bearing, IV-9 ZFO - UTC & Time
True heading, IV-5, IV-9 from Origin Waypoint, 38
TTM - Tracked Target Message, 35 ZLZ Not recommended - Table I-2
Two-way communication protocol, IV-9 ZTG - UTC & Time
to Destination Waypoint, 38
UART, IV-9 ZZU Not recommended - Table I-2
Undefined Characters, 8
Units of measure fields, 21
Universial Time Coordinated (UTC), IV-9 End of Index
Unreliable data, 10
Updates, 2

Valid Characters, 8, 15
Valid Sentences, 14
Variable length data fields, 9, 10, IV-9
Variable numbers, 21
Variable text, 21
Variation, IV-9
VBW - Dual Ground/Water Speed, 35
Video, 3
VLW - Distance Traveled, 36
VPE Not recommended - Table I-2
VPW - Speed - Parallel to Wind, 36
VTA Not recommended - Table I-2
VTG - Track Made Good and Ground Speed, 36
VTI Not recommended - Table I-2
VWE Not recommended - Table I-2
VWR Not recommended - Table I-2
VWT Not recommended - Table I-2

Waypoint, IV-9
WCV - Waypoint Closure Velocity, 36
WDC Not recommended - Table I-2
WDR Not recommended - Table I-2
WFM Not recommended - Table I-2
WNC - Distance
Waypoint to Waypoint, 36
WNR Not recommended - Table I-2
WPL - Waypoint Location, 36

Index Page 4
<EOF>

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