In GPS technology, the phrasing “COCOM Limits” is also used to refer to a limit placed to GPS tracking devices that should disable tracking when the device realizes itself to be moving faster than 1,000 knots (1,900 km/h; 1,200 mph) at an altitude higher than 60,000 feet (18,000 m). This was intended to avoid the use of GPS in intercontinental ballistic missile-like applications. Some manufacturers apply this limit literally (disable when both limits are reached), other manufacturers disable tracking when a single limit is reached.
Somewhat of a problem for homemade space programs?
40 thoughts on “GPS Units Disable Themselves If They Go Faster Than 1,200 MPH”
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I wonder what is stopping people from DIYing up a GPS receiver, its “only” an antenna, a high resolution timer and some maths.
Things like this are put in place for a reason, I get that, but any
determined group are likely to circumvent them if they want to.
http://www.holmea.demon.co.uk/GPS/Main.htm
A little more than “only” an antenna, though it is definitely feasible as the above link demonstrates.
Making sense: http://manhood101.com
Developing an efficient correlator requires a custom ASIC.
Yes correlators can be implemented in software or on an FPGA but that uses a LOT more power than GPS ASICs, which is bad for HAB.
No, it’s really not that simple. It’s much simpler to just go buy an unlimited high dynamic GPS.
“Somewhat of a problem for homemade space programs?”
Yes, but I’d think only to the simplest DIY attempts. Any state able to develop IRBM/ICBM should be able to make their own unlimited modules. Easily. Of course the same is true for any diehard space-ballooners. Of course the dual-type unit is usable as is. For balloons anyway.
The entire “COCOM” approach doesn’t seem sensible, only those who are already unable are prevented. I can’t argue with the intent but this implementation is broken. Seems a bit silly.
Actually, the way I’ve always understood it, the physical act of lifting a payload/warhead up to a high ballistic arc hasn’t been a “hard” engineering problem since WWII. The problem has always been having either GPS or ultra-high precision gyroscope technology in order to provide precise guidance so that you can have a decent chance of hitting a specific target on the other side of the world. This was one of the reasons that, during the original Gulf War, Saddam Hussain’s scud missiles had horrible accuracy and couldn’t even be expected to hit a specific city they were targeted at. Remember, the scud wasn’t even intercontinental. Even as a regional missile built by a, relatively, wealthy country it was highly inaccurate.
Actually, the way I’ve always understood it, the physical act of lifting a payload/warhead up to a high ballistic arc hasn’t been a “hard” engineering problem since WWII. The problem has always been having either GPS or ultra-high precision gyroscope technology in order to provide precise guidance so that you can have a decent chance of hitting a specific target on the other side of the world. This was one of the reasons that, during the original Gulf War, Saddam Hussain’s scud missiles had horrible accuracy and couldn’t even be expected to hit a specific city they were targeted at. Remember, the scud wasn’t even intercontinental. Even as a regional missile built by a, relatively, wealthy country it was highly inaccurate.
“Somewhat of a problem for homemade space programs?”
Oh I dunno, Apollo went to the moon and back without GPS, so I guess I’m inclined to think no…
“Somewhat of a problem for homemade space programs?”
Oh I dunno, Apollo went to the moon and back without GPS, so I guess I’m inclined to think no…
I don’t think GPS is gonna do any good on the moon anyway. ;-)
Hehe, true that :-P
GPS ought to work all the way up to 36,000 m (where the satellites are orbiting), and I see no particular reason why it wouldn’t work a bit above the geostationary satellite belt as well.
Directional antenna don’t point into space away from earth. Same issue as lunar. At or above gps sat orbit, you would be in the shadow, behind the transmitters
They built the first atomic bombs with WWII era technology but I don’t think that, even if it were legal, a homemade project would be able to build one from scratch (especially since the combined power from multiple full generator stations was required, over a LONG period of time, to produce even the tiny amount of weapon grade Plutonium/Uranium used). What you are missing is that even though the technology back then was much less advanced, they had access to the massive resources of a world superpower to make it happen.
“What you are missing is that even though the technology back then was
much less advanced, they had access to the massive resources of a world
superpower to make it happen. ”
To be sure. But in the case of our theoretical DIY space program, we more or less need the payload to be able to successfully leave orbit. As you actually say quite well in a later comment:
“The problem has always been having either GPS or ultra-high precision
gyroscope technology in order to provide precise guidance so that you
can have a decent chance of hitting a specific target on the other side
of the world.”
Which is not a concern for our space program in question. GPS doesn’t work outside of Earth’s orbit anyway, so its true utility is that of a convenient accessory, but not a requirement.
Actually, what IS a concern for our space program in question is successful navigation of space debris, something that largely didn’t exist back in the earlier days of space flight. It only takes one inconveniently orbiting toothbrush to take down your homemade space probe, and it only takes one brickduino coming close to a satellite, spacecraft, or space station to bring alot of government attention to DIY in general and really cranking up regulations (and violation penalties).
“What you are missing is that even though the technology back then was
much less advanced, they had access to the massive resources of a world
superpower to make it happen. ”
To be sure. But in the case of our theoretical DIY space program, we more or less need the payload to be able to successfully leave orbit. As you actually say quite well in a later comment:
“The problem has always been having either GPS or ultra-high precision
gyroscope technology in order to provide precise guidance so that you
can have a decent chance of hitting a specific target on the other side
of the world.”
Which is not a concern for our space program in question. GPS doesn’t work outside of Earth’s orbit anyway, so its true utility is that of a convenient accessory, but not a requirement.
Actually, what IS a concern for our space program in question is successful navigation of space debris, something that largely didn’t exist back in the earlier days of space flight. It only takes one inconveniently orbiting toothbrush to take down your homemade space probe, and it only takes one brickduino coming close to a satellite, spacecraft, or space station to bring alot of government attention to DIY in general and really cranking up regulations (and violation penalties).
Apollo
used a gyroscopic location tracking which is a lot more precise then a gps and
still they used the stars to double check the computer navigation
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It’s funny because you would think that anyone capable of building… well… the whole ICBM bit probably would be able to just make their own GPS component.
Yes, I can see it now…
“Oi! Bob! Seems this here ICBM needs a GPS unit!”
“Gah! I don’t wanna make a GPS unit… We’ve been slaving away on this ICBM thing for days.”
“Well, just pop down to the electronics shop and get one off the shelf then.”
It’s funny because you would think that anyone capable of building… well… the whole ICBM bit probably would be able to just make their own GPS component.
Yes, I can see it now…
“Oi! Bob! Seems this here ICBM needs a GPS unit!”
“Gah! I don’t wanna make a GPS unit… We’ve been slaving away on this ICBM thing for days.”
“Well, just pop down to the electronics shop and get one off the shelf then.”
NOW how am I going to find my way to Dollywood for vacation?
I’ll use inertial navigation like all good ICBMs do. They were used in the 1950’s so they’re probably a lot simpler to build than a GPS. The accuracy is good enough for an A-bomb or finding Dolly.
Actually this is the more minor problem for DIY space programs. Most consumer level GPS units won’t work over a few thousand MPH anyway because dopler shift becomes too much for them to handel.
It is possible to buy GPS units that don’t have the coded limits, and that have DSP to handle the dopler problem – but they are very expensive, and you have to turn over some level of documentation (although most of it is to prove you won’t violate ITAR).
Actually this is the more minor problem for DIY space programs. Most consumer level GPS units won’t work over a few thousand MPH anyway because dopler shift becomes too much for them to handel.
It is possible to buy GPS units that don’t have the coded limits, and that have DSP to handle the dopler problem – but they are very expensive, and you have to turn over some level of documentation (although most of it is to prove you won’t violate ITAR).
No good for your TomTomAtomBomb
So, I’ve actually dealt with this issue…
1) Consumer and commercial GPS units have serious issues with high vibration and acceleration. I think the issue is likely the SAW filters getting scrambled by the mechanical noise, but I don’t have the data to prove that. All I know is that they tend to give bizarre data under boost. There are also other problems with doppler at high speed, but the vibration limits bite first and *HARD*.
2) GPSes without COCOM limits are available on the market. You just need to convince the seller that you have a legit use and can be relied upon not to export it. These units are usually high-dynamic types as well, i.e. they don’t suffer from the problems described in (1)
3) It’s not clear whether or not the COCOM limits are required to be implemented as an ‘OR’ or as an ‘AND’ and different firmware makers do it differently. The ones that implement it as ‘AND’ (i.e. both 1000 kts AND 60 kft) can be used for high altitude ballooning, and that community keeps a list.
I understand now why the GPS in my pushbike stops working when I go a bit faster
Challenge accepted
Not really a problem, “serious” “homemade space programs” (Even if i’m not sure what this term really defines…) shoud use gyroscops, not GPS…
Not really a problem, “serious” “homemade space programs” (Even if i’m not sure what this term really defines…) shoud use gyroscops, not GPS…
If you’re building your own “space program” I’d be inclined to think that also tweaking a GPS to push the envelope would not be that much of a challenge.
And my wife can be heard for thousands of miles when I do something wrong. It’s genetic.
Sounds like a good reason to start an Open Source GPS project. If manufacturers are willing to build bugs into their system – don’t reward them by giving them money. Also – does this only apply to U.S. manufacturers? The United States can’t make rules for companies outside of its boarders – so it would seem that buying from a U.S. based company is completely off the table.
The GPS Satellite system was created and is owned by the United States (more specifically, the Department of Defense.)
I am guessing that at least some military units do not have that limitation, so I guess you could get military surplus units.
That is a ridiculous limit by paranoid people..
to legal launch a rocket into space in the usa you would need so much land(square miles) to get faa/government approval.. sometimes people goto redrock which is owned by the blm but im not sure how high they are allowed to launch from there legally.. gps would be the smallest issue to worry about.. as said by others apollo even hubble use/used gyros to detect movement
It is a problem. I wrote SpaceLab for iOS and have two iPhones on the International Space Station conducting experiments to demonstrate using low cost devices for research. We can’t use the GPS for that reason. GPS is used on some space vehicles, but they have specially built hardware and software that has been authorized. We decided not to even pursue modifying the iPhones to get around the limitation because that would defeat the purpose of the demonstration.
That jsut looks like its gonna be really good.
Anon-True.tk
I launched an amateur rocket that traveled at Mach 2.5 and aattained an altitude of 75,000 feet. Every second, every aspect of the launch, from ignition, to apogee and to the parachute controlled landing, was recorded accurately by the GPS receiver that was purchased llegally, from a US based supplier, for less than $60. This whole auto – shutoff thing is just a bunch of BS that someone made up to get more Facebook friends and more followers on Twitter.
Those limits, most likely, only apply to GPS units that are due to be exported out of the United States.