wa8yxm wrote:
GPS is a Satellite service, Just like DISH or DIRECTV.. you might want to read a few posts about the "Evil Signal Eating Tree" as it applies to GPS as well
My GPS works if it has a CLEAR view of the southern sky.. But My RV is wood and fiberglass and glass so not a lot of obstruction there.. My car, however, is steel, if I set the GPS up in the windshield area it works, going south but I've had cases where it looses sync going north because the roof is in the way.
I've had it loose sync on a "Tree lined street"
And I've had it loose sync due to lots of steel/concrete buildings or overhead wires.
gps just needs a reasonably clear view of the sky, not necessarily southern sky since the satelites aren't geo syncronous. but it needs a fix from at least 3 sat's to get your location, 4 to get elevation.
and vegitation, buildings are big attenators for the signal. deep canyons limit the number of sat's you can see. all bad. and metal is a big shield.
Now, the quality of the chipset in gps recievers varies all over the place. there are low power ones, there are high sensitivity ones, and everything in between. a low power unit is great for saving battery power but not good for reception. vice versa for the high sensitivity chip sets.
As an example the first spot units had a low power chip set to save battery life, but was terrible at getting a fix if you were moving or not in a clear location. the later units got much better fixes at the expense of lower battery life.
Likewise on different garmin handheld units. the early etrex suffered reception problems, the later units with a better chipset were far superior.
And, like a sat phone, gps does NOT work well inside any enclosed area. doesn't make any difference if it is metal, wood, plastic.
