garyhaupt wrote:
Unless things have changed, a phone GPS uses the cel phone towers. An actual GPS uses the signals from a minimum of 3 satellites. Cloud cover not withstanding a for real GPS is way t go, and even then, some common sense needs to applied.
Gary Haupt
Both Android and iPhone have the ability to use GPS directly. The Android (not sure about iPhone) can also locate position off cell towers. iPhone (not sure about Android) can use both the US and Russian satellites. I'm not sure about the newer Garmins, but the older ones didn't use the Russian satellites. The US satellite constellation was optimized for use over Europe and I'm guessing the Russians optimized theirs for use over the US, so you'll probably have fewer dead spots if you're using the Russians constellation. (St. Louis is a real dead zone for the US constellation.)
I think the biggest drawback of using a phone for GPS is that the maps are probably accessed via your cell connection. So if you're not getting cell signals your navigation may be a bit iffy. You don't have that problem with the Garmin or TomTom. To get a good location you need signals from four satellites minimum, unless you've got WAIS enabled. The GPS signal can be blocked by almost anything so you need a clear line of sight to the satellite. Placement of the GPS or GPS antenna in the RV can be critical because the RV can mask the signals. Most GPS receivers will mask satellites that are to low on the horizon, so while there may be 8 or 10 in the sky over you they may not all be usable.