Citing widespread interference on broadcast frequencies used by its member stations, National Public Radio has asked the Federal Communications Commission to order recalls of millions of FM modulators that drivers use to play satellite radios and iPods through their car stereos.I'm a big fan of my Sirius satellite radio, but I did notice that when I use the FM transmitter, the FM transmission signal went quite a distance.
A field study by NPR Labs found that nearly 40 percent of those devices have signal strengths that exceed FCC limits, enabling them to break into FM broadcasts in nearby cars with unwanted programming. A separate investigation by the National Association of Broadcasters found that more than 75 percent of the devices it tested violated the power limits.
For an anecdotal account, here's my own little experiment I conducted. I have the Sirius Sportster Replay and I currently transmit on 87.9 FM, which around here has no associated radio station. I left my receiver docked at home, and turned it on. I then got in my car, and drove a few blocks away. The signal remained loud and clear. My neighbourhood is pretty densely packed too, so do the math on figuring out how many houses I'd be broadcasting to.
Now, I broadcast on 87.9, but if I selected say 99.1 (the CBC Radio Toronto station), I wonder what kind of chaos that would cause? Andy Barrie is suddenly replaced by Howard Stern. Mmm ... :)