re: #74 ericblair

They then figured out that civilian GPS chips were programmed to stop responding if they recorded over a certain speed or altitude, since at that point GPS receivers were considered munitions and subject to export and usage restrictions.

The restrictions are still in place for over-the-counter GPS chips. I don’t know if the restrictions apply for any GPS systems that use the European Galileo satellites since that system is primarily commercial and not military like all the others (GPS, GLONASS, Beidou).

The knowledge base exists to make a GPS decoder that would actually work at all speeds and altitudes since the details of how they work are all known. I’m pretty sure I’ve seen mention of at least one open-source project to do just that. It’s not a simple single-chip solution that costs five bucks quantity 100,000 though, FPGAs may be involved.