Phantom GPS v TomTom!

[Fourblade]

I know you can't really compare a TomTom Satnav and the GPS unit in the Phantom but.... how come the TomTom locks on within a few seconds and the Phantom can take much much longer?

My guess is it's because the TT doesn't need as many sats to find it's 2D position - is that right?

 

[Dirty Bird]

I suspect that is part of the reason, as it only requires 3 satellites to obtain a 2D lock. The TomTom also maintains its ephemeris data, as well as time, date, and last known location onboard. My Garmin GPS locks up almost instantaneously when powered on. There is small rechargeable battery on the Phantom's GPS module, but I am unsure how much data it retains in memory between sessions, or how long the tiny power cell can maintain that data? If the Phantom GPS has to obtain all of that information each time it powers on, it would explain why it can sometimes take several minutes to obtain a fix.

 

[Meta4]

And the Garmin is happy with 4 satellites rather than 6 for the Phantom.
Watch the Garmin and it often takes longer to get to 6 sats after it has a 3D fix with 4.
Different antennas also have potential to affect performance.
Some of the Garmin handhelds have particularly good antennas.