Clock keeps correct time by listening to the radio (WWV/WWVH)
David Schachter
new product announcement in the two newgroups that are pertinent. (See pre-
ceding article.)
My company makes a product that may solve the hassles of shifting Daylight
Savings Time start/stop dates. The Precision Clock/Time Receiver, Model
OEM-10(tm) receives shortwave radio broadcasts from the U.S. National Bureau
of Standards containing the time and date. These broadcasts, on radio stations
WWV and WWVH, are converted by the clock into a format suitable for use by
computer systems and output through an RS-232 port. The N.B.S. transmissions
include a bit which is twitched twice a year, to indicate the start and stop
of Daylight Savings time and the clock has a switch to let you control whether
the bit is accepted or ignored. (The clock has other switches to let you
control other aspects of its behavior.) Anyway, before this turns into a sales
pitch, let me give you the address and phone number where you can get more
information, if you want:
Precision Standard Time, Inc.
2585 Scott Blvd.
Santa Clara, CA 95050
(408) 980-8001
(If you wonder, I'm the same David who used to work for Daisy Systems.)
John Chambers
The Zenith/Heathkit "Most Accurate Clock" (GCW-1000) has been around
for a while now and performs pretty much the same function as described.
Shop and compare before you buy. ;-)
--------
John B. Chambers
snail: MCC/Database, P.O. Box 200195, Austin TX 78720 USA
arpa: j...@sally.utexas.edu, db.ch...@mcc.com
uucp: {gatech,harvard,ihnp4,seismo,pyramid,...}!ut-sally!{,ghostwheel!}jbc
voice: +1 512 343 0860 x3478
Bob Devine
> My company [Precision Standard Time, Inc] makes a product that may
> solve the hassles of shifting Daylight Savings Time start/stop dates.
> The Precision Clock/Time Receiver, Model OEM-10(tm) receives shortwave
> radio broadcasts from the U.S. National Bureau of Standards containing
> the time and date. These broadcasts, on radio stations WWV and WWVH,
> are converted by the clock into a format suitable for use by computer
> systems and output through an RS-232 port. The N.B.S. transmissions
> include a bit which is twitched twice a year, to indicate the start and stop
> of Daylight Savings time and the clock has a switch to let you control whether
> the bit is accepted or ignored.
Note that the NBS broadcast of time services only gives the national
rule for changes from/to DST. That means those parts of the country that
have different rules must always ignore the bit. However, most states
could follow it.
A second point: Because the WWV and WWVB transmitters are in Fort Collins
Colorado, the signal strength is low on the east coast. I don't know if
this will necessarily cause intermittent reception or not. The field
intensity map supplied by NBS shows strength < 100 microvolts/meter east
of central New York state.
For those not familiar with the signal of WWV/WWVB call (303)499-7111
for the audio portion of WWV. WWVH (Hawaiian site) is (808)335-4363.
NBS says that what you hear over the phone line is within 30 milliseconds
of the actual time (lower 48 states only).
Bob Devine
David Schachter
Mr. Devine raises two points regarding WWV/WWVH radio clocks. His first point
is that some states do not follow the national Daylight Savings Time guidelines
and thus the WWV/WWVH broadcast will not work correctly with Daylight Savings
Time. He is correct. Automatic DST correction by the clock can be defeated
with a switch or through the serial port. Of course this reduces the useful-
ness of the clock. Question: are there enough localities with their own DST
rules that the PSTI clock should allow some user programmability of the DST
rules, perhaps letting the user enter start and stop dates over the serial port?
Mr. Devine's second point is the low signal strength on the East Coast. This
is not a problem, at least with the PSTI clock. We have several units working
on the East Coast. The signal strength on the East Coast is certainly lower
than nearer the transmitter (hey, that's not always the case with shortwave
radio!) but our receiver is very sensitive, and is designed to receive just
the five WWV/WWVH frequencies. A specialized receiver such as this can be
more sensitive than a generalized receiver, says the RF analog design guy. It
sounds reasonable....
[I am an employee of Precision Standard Time, Inc. and have a financial inter-
est in the firm.]
Uh, if you want to reply to this, perhaps net.unix-wizards is more appropriate
than net.misc.
-- David Schachter (408) 980-8001 noon-9pm Pacific Time
Bret A. Marquis
400 ready to go..
Chris Grevstad
>Heathkit offers such a beasty as well. 250 in kit form and about
>400 ready to go..
Can someone please email to me the address of Heathkit? Or better yet,
how do I get my hands on one of their catalogues?
As an aside, how good are their products?
--
Chris Grevstad
{sdcsvax,hplabs}!sdcrdcf!psivax!nrcvax!chris
ihnp4!nrcvax!chris
"Plan? There ain't no plan."
and...@hammer.uucp
>> 400 ready to go..
> Can someone please email to me the address of Heathkit? Or better yet,
> how do I get my hands on one of their catalogues?
Drop them a line at
Heath Company
Hilltop Road
St Joseph, Michigan 49085
and they'll send you a mail-order catalog.
WARNING. Don't go to a Heathkit store for a catalog. The store
catalogs are different, and some of the prices are higher than those in
the mail-order catalog. (Or at least they were in 1980.)
> As an aside, how good are their products?
I used to work at Heath. Some of their stuff is excellent, really
top-notch, like the old H19 computer terminal. Some of their stuff is
absolutely awful, like the old H9 computer terminal. There's no
pattern to it.
With regard to the clock, I heard that it worked pretty well if you
arrange things so that it continuously receives the time broadcast, but
that it's poor at maintaining the time-of-day when that broadcast
fades. This is third-hand information and not very reliable.
-=- Andrew Klossner (decvax!tektronix!tekecs!andrew) [UUCP]
(tekecs!andrew.tektronix@csnet-relay) [ARPA]