4 ms·
It's not dependent on the device. The satellites themselves send their position data but on a very low data rate (I think its just a couple bits per second) so
by worewood 6y ago
It's not dependent on the device. The satellites themselves send their position data but on a very low data rate (I think its just a couple bits per second) so if the device doesn't have the data it does take 15 or so minutes. Maybe the "cold-start" you are referring to wasn't so cold, it may have the almanac data saved from a previous utilization.
- eknkc 6y agoYeah, there are 3 possibilities. If there is absolutely no data cached in the device, it requires the almanac. Basically a map of all satellites in the constellation. Takes roughly 15 minutes because satellites transmit data really slow. This data is valid for a couple of months so a device can cache it a long time. If the almanac is present, it provices the coarse information. The device still requires precise status of the satellites it is receiving signal from. Each satellite transmits that within something like 30 seconds. So it would take 30 seconds for a precise fix. If the device knows everything about the constellation, can process the satellite signal immediately and pinpoint the location. If you are using a mobile phone, it should always be in this state because the required data is provided fast via internet. In case of other devices like offline watches, the almanac might be synchronised from time to time when you connect it to your phone or computer. And the fix would take up to 30 seconds.