Some Windshields Result to Poor GPS Signal Receptions

One of our products is AVLS, Automatic Vehicle Locating System that make use of GPS and GPRS technologies as the main methods to locate and gather data into our main server before displays it as a dot in a web-based map that can be accessed by our customers anyway thru the internet. A part of our customers will use it as a Fleet Management tool. We also experiences some poor data gathering which is sometimes maybe result by poor GPRS coverage, invalid GPS data & also by bad vehicle wirings.

I’ve a short conversation this morning regarding to invalid GPS data or poor data retrieval from units that have been installed into VIP cars. I didn’t get a clear picture about type of car or the maker. Our field technicians told that it’s because of tinted-windshield. Sounds reasonable to me anyway.

The VIP cars, for sure should be a luxury car, got it windshields tinted and some of it have embedded radio antenna built into it.

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.

Tags: , , , , , ,

Leave a Reply