>if I disable location and then reenable it when I have moved more than 20-30 miles, the GPS has to reacquire the signal and can take up to 2 minutes (I also tried it when I drove several hundred miles, it took several minutes to reacquire). This is indicative of the GPS module being off totally. This was not so when it had Google Play Services on, it was able to reacquire my location extremely quickly, sometimes almost instantaneously even if I moved a long distance. I suspect that Google Play was still tracking my location even if I turned off location services
This is more likely access to network assisted GPS.
To know your location, the receiver needs the GPS ephemeris and almanac data (basically the status/location/trajectories of the GPS satellites). This is transmitted by the satellites themselves, but extremely slowly (50 bps with the entire navigation message taking 12.5 minutes)#.
To speed things up substantially (almost instant vs minutes), this info can be delivered over the network instead. I presume that in your case it was being provided over the network as part of the Play services.
Heh, interesting. My assumption is that even network assisted GPS is a part of AOSP versus Play Service. This assumption was that UnifiedNLP [1] scans for networks/cell towers and correlates it to location, it does not appear to implement networked assisted GPS.
To know your location, the receiver needs the GPS ephemeris and almanac data (basically the status/location/trajectories of the GPS satellites). This is transmitted by the satellites themselves, but extremely slowly (50 bps with the entire navigation message taking 12.5 minutes)
Thanks for explaining that. It explains why when I interfaced a GPS receiver yanked out of a 2001 minivan it took so long to lock into a location with my Palm Pilot.
This is more likely access to network assisted GPS.
To know your location, the receiver needs the GPS ephemeris and almanac data (basically the status/location/trajectories of the GPS satellites). This is transmitted by the satellites themselves, but extremely slowly (50 bps with the entire navigation message taking 12.5 minutes)#.
To speed things up substantially (almost instant vs minutes), this info can be delivered over the network instead. I presume that in your case it was being provided over the network as part of the Play services.
# https://en.wikipedia.org/wiki/GPS_signals#Navigation_message