GPS Export Regulations (USA)
Todd Freestone
altitude limits on GPS receivers, with some folks asking where these
limits come from.
First, personal experience: We have several GPS receivers (Trimble, and
Ashtech) and they all *HAD* an altitude and velocity limit on them--For
example, our Trimble units were limited to +20,000 meters (66,000 ft)
altitude and 400 m/s (about 800 kts) speed. These limits are due to
software inside the receiver microprocessor--physically, their tracking
loops are capable of much higher limits. We signed the necessary
non-export paperwork, and got these limits removed--we needed to, as we
use the receivers in a low-earth-orbit environment.
Second, I did some digging and came up with the following, which is a
reprint of a photocopy that came from who-knows-where, but sounds
believable. I'm not sure how old the following is, whenit became
relevant, whether or not it still is, etc. But for those of you
interested, here it is:
"The U.S manufacturers of GPS equipment are subject to three export
control policies: The COCOM core list, the Missle Technology Control
Regime, and the U.S. Munitions List. Each policy's treatment of GPS
exports is being reviewed and revised."
COCOM Core List
" The Coordinating Committee on Multilateral Export Controls (COCOM) is
composed of seventeen countries, including Australia, Belgium, Canada,
Denmark, France, Germany, Greece, Italy, Japan, Luxembourg, the
Netherlands, Norway, Portugal, Spain, Turkey, the United Kingdom, and the
United States. COCOM controls exports to Albania, Bulgaria, the Peoples
Republic of China, Czechoslovakia, Hungary, Mongolia, North Korea, Poland,
Romania, the USSR, and Vietnam."
"Until this September, export of GPS equipment has been controlled under
the Commerce Department Export Administration Regulation 1501A. This
regulation required an individual validated export license for any GPS
equipment that did not meet the following criteria:
1. Capable of processing the L1 (SPS) channel
2. Capable only of the Short-Term Code (C/A Code)
3. No decryption capabilities
4. No cesium beam standards
5. No null-steerable antenna
On September 1, 1991, new COCOM regulations will go into effect for all
member countries. Essentially, all GPS equipment is eligible for general
destination (G-Dest) licensing, unless it meets the folowing criteria:
1. Employs encryption / decryption
2. Includes a null-steerable antenna"
The Missile Technology Control Regime (MTCR)
"The MTCR was recently formed among a group of nations to control exports
of equipment with potential use in missile guidance systems and the
production of ballistic missiles. The member countries are Australia,
Belgium, Canada, Denmark, France, Germany, Italy, Japan, Luxembourg, the
Netherlands, New Zealand, Norway, Spain, the United Kingdom, and the
United States. The organization will restrict exports to countries in the
Middle East, Southeast Asia, and other areas."
"In discussions with MTCR Government representatives, the U.S. GPS
industry proposed a set of altitude and speed limitations that would
distinguish GPS equipment intended for normal commercial use from
equipment that could be used to guide ballistic missiles. It is our
understanding that these altitude and speed parameters have been adapted
as part of the MTCR criteria:
1. At speeds in excess of 515 m/sec (1,000 nmi/hr)
2. At altitudes in excess of 18 km (60,000 ft)
"The COCOM criteria became effective September 1. It is anticipated that
the MTCR implementation schedule will be finalized before the end of this
year."
The U.S. Munitions List
"The USML pertains to U.S. exports intended exclusively for military-end
use. Goods and technologies placed on the USML are subject to unilateral
export controls. The President's Executive Order Number 12735 issued on
November 16, 1990 required that the USML be harmonized with the COCOM Core
list decisions, greatly reducing the number of GPS equipment categories
subject to control."
"The USML is still under final inter-agency review, but it appears that
the position proposed by the U.S. GPS industry, which closely parallels
the COCOM Core list and MTCR positions, has become the basis for the class
comodity jurisdiction announced by Assistant Secretary of the Air Force
Martin Faga."
--------------------end of photocopy--------------------
Well, that's all I know....hope this satisfies any curiosity's out
there....If there's any followups or additions, please either chime in
with a followup here, or E-mail me directly, and I'll post a followup later.
Todd Freestone / KD4ALP to...@sauron.msfc.nasa.gov
Radio Frequency Branch
NASA / Marshall Space Flight Center
Thomas M. Corrigan
>There have been several thread discussions recently about velocity and
>altitude limits on GPS receivers, with some folks asking where these
>limits come from.
..lots of interesting stuff deleted
thanks for the information. When I said there were no altitude / velocity
limits to GPS, I was talking Physics. God only knows what politicians will
come up with to remove it from the relm of science, but it certainly bears
watching if your involved with civilian applications. Most of our (APL)
experience has been with military (PPS) receivers, but I knew any
restrictions had to be 'self' imposed in the receiver software ! :-(
---------------------------------------------------------------------------
Tom Corrigan
corr...@aplcomm.jhuapl.edu
oppinions expressed here do not reflect those of JHU/APL
as far as I know, they don't have any .....
----------------------------------------------------------------------------
Lee Groves
> Todd Freestone (to...@sauron.msfc.nasa.gov) wrote:
>
> [Stuff deleted]
>
> : 5. No null-steerable antenna
>
> Ok, who can tell us exactly what a null-steerable antenna is and what it
> does for you?
Wild guess:
I bet it's an antenna that keeps its lock regardless of how much
it is moved around. --handy if you're building a cruise missle
that makes sudden turns/manuvers...
(but I'm probably wrong...)
Lee
.
Thomas M. Corrigan
writes:
Well no, actually. Null steering refers to the ability of some antenna
systems to 'point' nulls at a given direction(s) in space. They respond to
jammers by directing nulls in their direction. An 'N' element antenna ( and
associated controller electronics ) can point N-1 nulls at jammers.
A similar idea is called 'beam steering', which refers to pointing increased
gain at the satellites.
BTW- cruise missiles are relatively low dynamic vehicles ( as such terms are
usually used ), and don't need much help maintaining lock through maneuvers;
what help they need comes from 'inertial aiding', where velocity information
is passed to the tracking loops from an inertial measurement unit ( gyros /
accelerometers ). ( to be more exact, the IMU is mostly for navigation
if/when the GPS receiver is jammed out ).
Tom Corrigan
corr...@aplcomm.jhuapl.edu
Lee Groves
>>..
> Well no, actually. Null steering refers to the ability of some antenna
> systems to 'point' nulls at a given direction(s) in space. They respond to
> jammers by directing nulls in their direction. An 'N' element antenna ( and
> associated controller electronics ) can point N-1 nulls at jammers.
So is this a phased Array sort of system?
( sorry that the following is a bit off the topic)
> BTW- cruise missiles are relatively low dynamic vehicles ( as such terms are
> usually used ), and don't need much help maintaining lock through maneuvers;
> what help they need comes from 'inertial aiding', where velocity information
> is passed to the tracking loops from an inertial measurement unit ( gyros /
> accelerometers ). ( to be more exact, the IMU is mostly for navigation
> if/when the GPS receiver is jammed out ).
One of my "someday" projects is to build a radio controlled airplane
with an embeded guidance system using a hand-held GPS and a custom
flight management system. There are already cheap gyros for keeping
the wings level available on the market ( < $200 ). The idea is
to have this thing take off in Tucson and then jump in my car and
drive to my home town (on the other side of some mountains a hundred
or so miles away) and see if it arrives and starts circling at the
prescribed location. There is plenty of computing power available
in small STD-bus CPUs (with built in IO!). I was going to digitize
my own topo maps, but I have heard that these are available already
(any ideas where?) 100 meter positioning would get me through
the mountain passes. The total cost for this project could be as
low as $1K. --which is pretty cheap considering what you get, and sort
of shows why the government is a little worried about cheap high
accuracy units getting out of the country. Add a pound or so
of something very explosive, and deliver it within 5 meters,
and you've got quite a terrorist weapon! Can you imagine Iraq
sending a thousand of these at Israel, or the IRA sending
a hundred to England? Frankly, I'm surprised that civilain
access to this system is allowed at all.
I'm a real-time systems programmer, but not some sort of super guru.
The GPS unit does all the hard stuff. The code is something like
for( each intermediate point){
while( not yet to intermediate point ){
Get currpent position
generate error and new heading
follow new heading
}
}
you are there.
The hardest part of this whole thing is "get current position",
and GPS does a stunning job of this.
Scary, huh?
Lee
Thomas M. Corrigan
writes:
( discussion of Null steering arrays....)
>
>So is this a phased Array sort of system?
>
>
YES
Gavin Scott
[Stuff deleted]
: 5. No null-steerable antenna
Ok, who can tell us exactly what a null-steerable antenna is and what it
does for you?
Gavin
--
Gavin Scott - Quest Software Inc - ga...@quests.com -or- gsc...@netcom.com