I used to have a Focus, plus Palm m505/Navman 500 GPS combination. The heated windscreen element does reduce the GPS signal strength considerably, but still allows enough signal to get through to get a good fix.
However, the signal is weakened, and you can lose the fix by going under bridges etc. It was not really ideal.
Stevie is right. There are patches of windscreen at the lower extremes at either end where there is no element. The GPS worked loads better when I put it there. If you get a bluetooth GPS, you won't have any problems if you stick it at one of the "blank" ends of the windscreen and mount your PDA wherever. |