For the last couple of weeks I have been listening to the 7th Harry Potter book on an MP3 player in the car. I am using an FM modulator to get the signal from the MP3 player to the car’s speakers. I can choose to have the modulator broadcast on any frequency in the FM band, but it works best if it doesn’t have to compete with other, possibly stronger, signals. The default for an unset preset on the car radio is 87.9 FM, the very low end of the FM band. It just so happens that no local stations use this frequency, so I figured I’d use it.
While driving around, I would experience interference and static sometimes. After a few days of the commute I determined that it wasn’t in any particular location; the static seemed to happen whenever it wanted to. During on of the times when there was static, I tuned my transmitter to another frequency, just to rule out that it wasn’t part of the recording or a defect with the MP3 player. When I tuned my transmitter away I was blown away by crystal clear &em; and very loud &em; heavy metal music. I thought this was an isolated event at first.
I started turning off the transmitter any time I heard static, and in every single case, there was another signal coming from another car! I was astonished. I know there are FM modulators available that work with iPods, but I was amazed by how many people were doing the same thing I was. I wouldn’t think it would be very popular. After a while I deduced that most of the signals came from satellite radio. I guess the little boxes for cars that receive satellite radio come with FM transmitters to make car installation easier. I’m guessing that most of them default to using 87.9 FM.
If you want to try this yourself but don’t want to listen to minutes of noise in between hits (the whooshing sound makes me sleepy) try just switching over to 87.9 FM at intersections. The more cars you can get close together, the greater your chances of picking up on a signal will be. If you get lucky, then the signal will be coming from one of the cars traveling the same direction as you, then you can listen to it until you get too far apart. It can be fun trying to figure out which car is listening to the Howard Stern show. I’m usually wrong, though. I think I know which car it is, then the actual car will turn off the road and the signal fades away.
Have fun, but be safe. Don’t let the random transmissions distract you from your primary driving responsibility.