signal strength - line of sight etc

[donster22]

hi

i have just received my gr230 and am just waiting for my ipaq to arrive.
the gps is sitting on my windowsill and eventually gets a fix but if you move it a few or turn it it seems to lose the signal - ie the light stops flashing.
is this right? i'd heard that once a fix had been obtained you could put these things in your glovebox and they'd be ok. how's that going to work if it loses the fix 1 metre into my bedroom?

also, does anyone know what the difference in technology is that means CF card must have a view of the sky to get a fix but the bluettoth gps can be in the top of a rucsac?

thanks
don

[nej]

As GPS works by receiving radio signals from above, the receiver must have a view of the sky. That said, it doesn't necessarily have to be unobstructed... the thin lining of a rucksack, for example, will not stop the radio signals, a piece of plastic (i.e. your dashboard) may not stop the signals, however a piece of metal will. If your dashboard had any metal in it, then it wouldn't work in your car. In my car, I usually get a signal if the receiver is on the seat of the car. Obviously, nothing comes in through the metal roof of the car, but it still picks up enough from the windscreen and other windows.

As for in your house, right by the window is obviously enough for it to see the sky, but a meter further in it's view is extremly limited, and the signals won't pass very well through tons of bricks, mortar, wood and roof tiles. You need 3 satellites for a basic 2D fix and 4 for a better, 3D fix.

Hope that clarifies a bit.

-Neil

[nej]

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