Poor GPS Reception with Certain Car Windshields
I’ve had a few conversations with people recently who were experiencing trouble getting good GPS signal quality in their vehicles. In one case the GPS was new and it was the first time they had used a GPS receiver. Another reader asked why their trusty GPS suddenly didn’t have god reception and their backup GPS suddenly didn’t have good reception either. In both cases it ended up being something about the vehicle that was causing the issue.
Let’s talk just a little bit about how GPS works. Think of your GPS receiver as a little FM radio. The GPS satellites send signals that your GPS receiver can listen to. In fact, the frequency that GPS signals are broadcast over are on a frequency simlar to that of FM radio (1200 MHz and 1500 MHz areas). Anything that might disturb good reception over FM radio can also cause signal issues for GPS receivers.
It turns out that both of our readers were in vehicles where the FM antenna was built into the windshield. In one case the car was new to the reader and thus they didn’t notice that the poor reception had started when they started driving the newer vehicle. In the other case the driver was finding that the GPS could only pickup a good signal when on either side of the dashboard; when it was in the middle it was under the FM antenna and they had a difficult time getting a solid GPS signal.
I’ve also heard sporadic reports that certain tinted windshields can interfere with GPS reception although I haven’t been able to see this happening with my own eyes. So the type of car you drive (or more specifically the type of windshield you have) can interfere with the GPS signal. If your vehicle has a windshield with an integrated FM antenna you might need to locate the GPS receiver away from where the FM antenna is located to get good reception. I even heard from one reader who said their FM radio would no longer work when they turned on the GPS.