Dear sir,
How much time to fix GNSS data in MC60_CA normally . Our module take 10 min for fixed GNSS data then what should be reason. sometimes it takes more than 10 minutes. Device is in open sky.
How much time to fix GNSS data in MC60_CA normally . Our module take 10 min for fixed GNSS data then what should be reason. sometimes it takes more than 10 minutes. Device is in open sky.
Time-to-first-fix (TTFF) in GPS depends on multiple factors. The worst case for every device should be a little over 12.5 minutes, because GPS devices need to download the so called almanac first, and the almanac is transmitted over a period of 12.5 minutes (750 seconds) by the satellite constellation. For the same reason, most manufacturers quote 13-15 minutes, which includes the 12.5minute almanac download plus some leeway for guarantees. Using nothing else than the satellite signals, nobody (no device and no manufacturer) can do better than 12.5 minutes, as this is not device-specific but determined by the send intervals of the satellites themselves.
Note that the above 12.5 minutes pertains to the GPS system at cold boot. If you use your GPS device regularly the actual time-to-fix should be much shorter. First of all, the almanac data may be pre-cached from earlier runs so it may not need to be downloaded (though the cache the will loose its validity if it is too old). Second, there are alternate sources for the almanac data, such as AGPS or an active internet connection, which will improve the cold boot time by providing a faster way to download the almanac. Third, your GNSS device might support other systems than just GPS (such as GLONASS, GALILEO etc.), which may get an earlier fix, so even tough technically you don’t have a fix for GPS, you still get location data from a different satellite constellation.
Many of these accelerating factors actually apply to the MC60. It supports GLONASS that has a TTFF of only 150 seconds instead of 750, and the MC60 also supports AGPS. Still, your worst case is a little over 750 seconds: if all you have is a single civil GPS signal, and no almanac data (such as first time out of factory) or the data is severely outdated, and you have no other connection to get it faster, 750 it is.
As one more note of interest, the GPS L2C, L1C civil-use signals are under deployment, which should allow a much faster worst case. However, while partially already deployed, none of these are officially operational yet, so it is unlikely that Quectel has support for these on current products. But at least in the future, it will get better than 750 seconds for new hardware.