An Experiment with My FM Radio Transmitter

A while ago I talked about how I had trouble playing music in my car because it doesn’t have an aux port. As I mentioned in that post, I decided to use an FM audio transmitter, but one of the problems with this is that the signal could potentially be picked up in nearby cars. I had some evidence that this was possible, but I figured I should actually test this out.

Here’s how I set up the experiment: I parked my car, loaded some music on my phone, and hooked it up to the FM transmitter. Then I grabbed my MP3 player (which has an FM radio) and walked around while listening for the signal, in order to find out how far it could reach.

The signal was clear within a radius of about one car length (about 16 feet for my car), and I was able to pick up a broken signal within one and a half car lengths. I normally tune the transmitter to an unused frequency, so I wondered what would happen if I changed to the same frequency as a major radio station. In this case, the signal was clear within about half a car length, and I could pick up a broken signal within one car length.

Of course, this isn’t the most rigorous experiment, but I think it demonstrates that it’s at least plausible for the signal to reach other cars. I could imagine other cars picking up my personal listening when I’m stopped at an intersection or stuck in heavy traffic. On the other hand, this also suggests that maybe I don’t need to worry about that if there isn’t any traffic and there is a reasonable distance between cars. A better experiment would be to try tuning in from another car, to better replicate the real-world conditions I’m investigating.

Ultimately, I’d still like to have something that doesn’t rely on FM radio signals. Ideally I’d find a Bluetooth transmitter that works in the car, but I’m not too optimstic in that regard. Who knows, maybe I’ll figure something out.