i posted a long text already once, but i can't find it so ill just make a short summary,
all the newer phones have good gps, the newest, have A- gps + GLONASShttp://en.wikipedia.org/wiki/List_of_smartphones_supporting_GLONASS_navigationhttp://en.wikipedia.org/wiki/List_of_devices_with_assisted_GPS>there is no difference in quality of gps systems
SINCE THE DATA IS DIGITAL, position is then CALCULATED, same data same precision.
all satellites send “ i'm at position xzy this signal was sent at the time of zxy, and a weather correction factor” (modern even send atmospheric correction parameters) GLONASS goes down to 1 meter precision.>butt xzy is faster ?
Differences come from the power of the device, Calculations per second. >What about reception?
Weather normal doesn’t influence reception, snowfall, Heavy rain, wet foliage can,>Phone is better since it has A-GPS
Standalone GPS provides first position in approximately 30–40 seconds ( but can take to 12 mins) . A Standalone GPS system needs orbital information of the satellites to calculate the current position. The data rate of the satellite signal is only 50 bit/s, so downloading orbital information like ephemeris and almanac directly from satellites typically takes a long time, and if the satellite signals are lost during the acquisition of this information, it is discarded and the standalone system has to start from scratch. (this why car gps is so shit and takes ages ) In AGPS, the Network Operator deploys an AGPS server. These AGPS servers download the orbital information from the satellite and store it in the database. An AGPS capable device can connect to these servers and download this information using Mobile Network radio bearers such as GSM, CDMA, WCDMA, LTE or Wi-Fi. The data rate of these bearers is high, hence downloading orbital information takes less time.