Most of the GPS are compliant with what is called “COCOM Limits”. Here is the issue!
Indeed, it refers to a limit placed to GPS tracking devices that should disable tracking when the device realizes itself to be moving faster than 1 200mph (1 900 km/h) at an altitude higher than 60,000 feet (18,000 m). In such situation, the GPS receiver continuously resets until the situation is cleared.
The objective of such limitation was to avoid the use of GPS in intercontinental ballistic missile-like. applications.
Some manufacturers apply this limit literally and disable the GPS tracking when both limits are reached when other manufacturers disable tracking only when one of the limit is reached (higher than 60 000 feet OR moving faster than 1 200mph).
High-altitude balloons are released into the stratosphere, generally reaching between 60,000 to 120,000 feet (18 to 37 km). For such application, 1 200 mph speed limitation is not an issue but the altitude limit is one!
Therefore, if you want to be able to track your balloon as we would like, you have to choose a GPS using an OR statement that would continue to function above 60 000 feet.
This is the case of the uBlox MAX-6 we have chosen. Order placed this last weekend on
HAB supplies website.
Max altitude: 164 041 feet (50 km)
Support temperatures down to –40°C.
