I am looking for a GPS module that I can use in a high-altitude project. The problem I have discovered is that GPS manufacturers are required to place a set of restrictions on GPS modules. The restrictions set a maximum speed and altitude at which the device should stop functioning. Basically, this limits someone's ability to build a cruise missile.
From what I understand, it is not illegal to have a GPS receiver without these limitations, it is illegal to export it from the U.S. without considering it a weapon.
If I am not mistaken, GPS is also used to track some satellites in orbit, so as long as the orbiting satellite is not in geo-synchronous orbit or further. Obviously, these GPS receivers do not have the limit, as both the height and velocity would far exceed the mandate.
Does anyone know of a GPS unit that does not have these limitations, or, is there a unit that allows you to flash the firmware and manually remove the limitations?
Link to mention of limitations: http://en.wikipedia.org/wiki/CoCom#Legacy
Best Answer
Here's a page that discusses several models of GPS that are known to work in balloon applications: http://ukhas.org.uk/guides:gps_modules
It looks like the COCOM limits are imposed differently by manufacturers - some use an altitude 'OR' speed limit check, the others use 'AND'.
My next question would be just how much 3D accuracy you would get out of a GPS unit at 100,000 feet!