You know them, you need them, you hate them: FM transmitters are the only affordable iPod-to-car audio integration option for owners of many cars, enabling users to broadcast the iPod’s music to any car’s FM radio at a relatively low level of quality. Despite the fact that they rarely sound better than $15 cassette tape adapters or $10 auxiliary audio cables, these ~$50 transmitters are the only solution for tape or aux-in-less car owners, short of replacing the car’s stereo with something more iPod-compatible. That’s why FM transmitters remain one of the biggest-selling categories of iPod accessories, despite the fact that users routinely complain about their sound quality.

FM Transmitters’ Dirty Little Secret: FCC Violations

FM Transmitters’ Dirty Little Secret: FCC Violations

Why so many complaints? Every country’s government controls FM airwaves within its territory, granting licenses to large broadcasters to perform audio and data content on a potentially massive, multi-city scale, using a single FM station such as 88.1 FM, 103.3 FM, and so on. Because these governments do not want smaller or unlicensed broadcasters to interfere with the signals broadcast by larger, licensed ones, they strictly control the broadcasting power of smaller and consumer-grade broadcasting devices, with rules that limit personal-use FM transmitters (also known as Part 15 devices) to a very low power level – at maximum, enough to create almost radio-quality clarity at a distance of a few feet away. The result is an FM transmitter that can interfere with any radio nearby – in a car, or in an immediately adjacent home stereo – but barely intrude upon your neighbor’s car or home stereo. Unfortunately, if there’s any radio programming already on the channel selected by these transmitters, they create an even lower-quality signal than normal, and most users don’t know how to find “good,” totally empty stations to use.

[Editor’s Note: iLounge’s FM transmitter reviews are conducted in the tough, radio-heavy Southern California market, and have long employed a systematic method for testing, using three specific stations to test “best case” (87.9FM) “good case” (88.3FM) and “bad case” (103.3FM) transmitter performance rather than generalizing that a transmitter is always good or bad across all stations. Since the FCC has blocked almost all commercial radio broadcasts on 87.9FM, users in the vast majority of the United States (except for San Francisco, one city in Texas, and a handful of places with pirate radio stations) can use this station to achieve as clear an iPod audio signal as possible. If a transmitter cannot transmit on super-clear 87.9FM, we instead use local 88.3FM as a proxy for what a pretty good station will sound like, and 103.3FM as a test of how the transmitter does on a station with significant local radio interference.]


FM Transmitters’ Dirty Little Secret: FCC Violations

As a consequence of user complaints – and a fairly easy way to fix them – the FM transmitter market has a dirty little secret. It’s not the obvious one, which is to build the transmitter so that users can easily modify it and boost signal strength on their own. Rather, it’s selling transmitters that are overpowered directly out of the box, something that no user will ever complain about, but her neighbors – or other transmitter manufacturers – will.

To gain a competitive advantage over established transmitter makers, many new companies just ignore the governmental broadcasting regulations, creating transmitters that are more powerful than the government allows. A lot of the fudging is small-scale – a transmitter gains a little extra clarity when left up close to a radio, or has a few extra feet of signal strength. But once in a while, a company releases a transmitter that is almost insanely over-powered.

A number of recent XM and Sirius satellite radios contained these super FM transmitters, designed to let their satellite programming be heard flawlessly on existing home or car stereos. In May, the Federal Communications Commission (FCC) stepped in, forcing XM to pull its non-compliant radios from shelves, and in July, Sirius followed suit. Spurred by a June report from the National Association of Broadcasters, a group representing the broadcast industry, the FCC is now looking into even more FM transmitter accessories. The NAB published a study in which 17 different transmitters from various manufacturers were tested; 13 of them (“76%”) were alleged to be in violation of the FCC’s standards. Six of the devices were at least 20 times stronger than the FCC’s limits, and one was 200 times stronger. iPod accessories from C. Crane, Griffin, and Monster were on the list, and compliant; now-discontinued models from Belkin were amongst the many non-compliant ones.


FM Transmitters’ Dirty Little Secret: FCC Violations

Does any of this really matter to consumers? Not in a directly positive way, unless you’re really concerned about protecting your neighbors from audio interference. In the near term, you should expect major manufacturers to become more concerned about FCC regulations, and non-compliant transmitters (read: super-powerful ones) to become less common in products by big companies. But small companies will likely continue to churn out non-compliant devices. Why? Profit potential. Every month or two, iLounge receives an e-mail from another company considering the release of a new FM transmitter, inquiring whether we’ll take a look before the decision is made to actually sell it. This letter we received in July is fairly typical:

“We have been offered an FM Transmitter and are debating whether we want to carry and offer it. […] It’s nothing special in appearance however it is very powerful. I have been using it in my car for about 2 weeks now and have given a few out to my friends and they have all ended up wanting to keep them so we think there maybe a market for it (even though there are plenty of FM transmitters on the market already).”


FM Transmitters’ Dirty Little Secret: FCC Violations

We sent this company our standard response: “If it’s very powerful, it’s either violating FCC broadcasting regulations (most likely) or exceptionally well designed (less likely). Because there’s so much spec-fudging that can be done when it comes to FM transmitters, and because people complain so much about even the best of them, we’re not interested in testing anything except for final shipping products in this category.”

As reviewers of iPod accessories, including FM transmitters, our goal is to keep our readers informed about the best products on the market, but we also want to be fair to companies that play by government rules in manufacturing law-abiding products. Though we expect FM transmitters to decline in popularity as better iPod integration solutions for home and car use proliferate, you can expect more FM transmitter reviews from us in the future, including some details on FCC compliance – you can ultimately make the best choice about what’s right for your own needs.

Jeremy Horwitz

Jeremy Horwitz was the Editor-in-Chief at iLounge. He has written over 5,000 articles and reviews for the website and is one of the most respected members of the Apple media. Horwitz has been following Apple since the release of the original iPod in 2001. He was one of the first reviewers to receive a pre-release unit of the device, and his review helped put iLounge on the map as a go-to source for Apple news.