A GPS Tracker has two components. A GPS receiver is used to receive signals from multiple GPS satellites in order to triangulate the current location of the vehicle; and the location data are then transmitted through commercial Mobile Phone networks to the intended recipient. One can detect those RF transmissions using various RF detection tools.
A frequency counter is one of such tools to determine the radio frequency of electromagnetic (EM) signals sent or received. This particular one I use is designed to pick up both analog and digital signals. The detectable frequency range is 30 MHz to 2.8 GHz, which covers most of the commercial mobile phone service frequency bands.
As a matter of fact, our ambient environment is always filled with weak EM signals, or noise. The frequency counter is designed to ignore the noise and pick up only those EM signals exceeding certain theshold of strength. In your house there are many sources of EM signals, such as mobile phones, microwave ovens, wireless routers, cordless phones, ipads, Xbox, etc. Depending on the strength of signal, detection range of frequency counter fluctuates from one foot up to 10 feet.
While the frequency counter is good at detecting the presence of EM signals, but it is not designed to pin point the location of the sources that emit the signals. For example, one can use this to detect whether there are cellphone signals present in the conference room during a meeting, but it is hard to determine which participant is texting on the phone and not paying attention to the new corporate strategy.
If you plan to use this frequency counter to detect the mobile phone signals, then make sure you get the one that picks up both analog and digital signals,
I purchased mine at MCM Electronics. Click on the following link to check it out.
If these RF signals are indeed emitted by a GPS-Tracker on the car, then the question is who planted it and is such act lawful??