Why GPS Trackers Have a Speed Ceiling
A GPS receiver does not measure speed directly. It compares signals arriving from several satellites to work out its position, then calculates how that position changes over time. The radio signals do not suddenly stop being usable when a device moves very fast; the cutoff is imposed by the receiver’s software.
Many commercial receivers include a safeguard often called a COCOM limit, named for a former export-control committee. In common implementations, the receiver stops providing position data when it is both above roughly 1,000 knots (about 1,150 mph) and above about 60,000 feet. The often-quoted 1,200-mph figure is a rounded version of that speed threshold, not a universal tripwire for every tracker.
A Safeguard Built Into the Firmware
The restriction reflects concern that precise satellite-navigation equipment could be used to guide long-range weapons. Manufacturers incorporated limits into receiver firmware so a unit would not deliver navigation data under conditions associated with a fast, high-altitude vehicle. Depending on the model, it may stop reporting a position or otherwise limit operation; it is not necessarily the whole tracker powering off.
That distinction matters: an ordinary car tracker can exceed highway speeds without triggering the safeguard, because it remains far below the altitude condition. And a device’s behavior depends on its design and settings. The memorable “1,200 mph” rule is shorthand for a specific kind of built-in restriction—not a speed at which GPS itself fails.
