If your car has a heat reflecting windscreen it will attenuate the signals from the satellites dramatically. On my car (a Citroen C5) there are a couple of patches on the windscreen that are not coated. If I put the GPS receiver on one of these patches it will ususally get 5-7 satellites, but if I put it elsewhere on the screen it will only get 3-5 and will tend to drop out in built up areas where the signals are blocked by buildings.
I also stick the receiver to the windscreen with Blu Tac with the silver side facinf outwards because that also increases the sensitivity. |