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They shut themselves down if they detect you are travelling around Mach 2 or above 18000 metres altitude The intention was for a GPS device to disable itself i
by mct 13y ago
They shut themselves down if they detect you are travelling around Mach 2 or above 18000 metres altitude
The intention was for a GPS device to disable itself if it was traveling faster than 1k knots AND above 60k feet, not traveling faster than 1k knots OR above 60k feet. Unfortunately, many GPS devices improperly implement this as an OR condition, rather than an AND condition. This becomes problematic when using a GPS in a high-altitude weather balloon to determine altitude and location, which a few friends and I did a couple years ago. We had to be very careful when selecting the GPS we used to avoid this pitfall.
- AlexDanger 13y agoInteresting, I did not know that. Which GPS did you end up using?
- wyager 13y agoWhich GPS units are acceptable for this? I'm working on a HAB and I'm worried about this CoCom bullshit. The one I'm thinking of uses a SiRFstarIII or IV; any idea of those use || instead of the proper &&?
- ash 13y agoWikipedia article on CoCom links to a post that links to this page: http://ukhas.org.uk/guides:gps_modules http://ukhas.org.uk/guides:gps_modules
- mct 13y ago(Apologies for the untimely reply) We used a UBlox5, which we purchased from diydrones.com. This was in 2009, so that particular model is now outdated. Both Adafruit and SparkFun now sell devices which are explicitly listed as being HAB-friendly. There's also good guide at http://showcase.netins.net/web/wallio/GPSrcvrsvs60kft.htm http://showcase.netins.net/web/wallio/GPSrcvrsvs60kft.htm. That page states that SiRF-I and II are known to fail above 60k feet, and that some SiRF-III-based receives fail, while others don't. (If you happen to be in the Bay Area, I'd be happy to meet up and give you guys some pointers sometime; drop me a private email.)
- ttflee 13y agoHow about the GPS inside Android/iPhone?