(Commentary) The popular industry email bulletin CGC Communicator published by Communications General Corporation consulting engineer Robert Gonsett ran a series of summary articles this year on the emissions of what he terms “mini-transmitters” used for getting audio from satellite receivers to automobile FM radios. At question was the power and frequencies chosen for the job.

Sometimes taking on entrenched forces of big business and big government becomes a hopeless morass of stonewalling and legal manuevering; the one with the most expensive den of attorneys wins. At other times, the system works. Follow along as we piece together the story of how one person can shed enough light on foul activity to make a difference.

This story began nearly two years ago, shortly after I took the job as Chief Engineer at the XETV Fox 6 studio in San Diego. Disclosure: XETV retains well-known consulting engineer Robert Gonsett specifically to deal with matters of interference, be they intentional or incidental. The actions taken by Bob were largely done by his own initiative, though I am left personally grateful and somewhat astonished from the lesson of power in process and persistence.

The Punching Bag of TV Spectrum

Pity the poor channel 6 over-the-air viewer in San Diego. First of all, the signal’s low band VHF, which means viewers must contend with urban electrical noise and the visual blight of a large antenna, if they bother at all. Then there’s the distance from the transmitter in Mexico to viewers north of Mission Valley. Add that the XETV’s power is split between horizontal and vertical polarization so that unless you have a special circular polarization receive antenna, you can’t receive the full signal. And then we deal with the adjacent band noncommercial FM broadcasters who want nothing worse than to improve coverage for their deserving listeners. The latest assault, however, comes from the proliferation of little FM modulators people use to transfer without wires the audio from their file players and various satellite receivers to a stock automobile FM stereo radio.

Those FM modulators are termed by the FCC “intentional radiators,” which means that their radiation is intended, in contrast to the unintended radiation from, say, your computer’s switching power supply. Under FCC regulation 15.209(a), such intentional radiators must have a fundamental signal within the FM band measured at no more than 150 uV/m at 3 meters distance, and they’re just plain not allowed on TV channels 5 and 6.

The  Journal

2005 – I begin receiving occasional calls from viewers who say that they are watching us when the colors  flash and they can hear music or voices unrelated to the video emanating from their TV speakers. Their interference comes and goes as do their neighbors. Obviously, this must be occurring with other channel 6 outlets around the country.

December 2005 – Gonsett’s newsletter, the CGC Communicator, relays a report from an LA radio chief engineer that a pirate broadcaster he picks up on his car radio is actually an XM satellite receiver FM modulator. “It amazed me how far I could hear the FM modulator….at least 250 feet if not further. This is the second time that this has happened to me while driving around…I strongly question whether these XM modulators are Part 15 compliant because they are able to radiate signals over 250 feet….”

March 11, 2006 – The Philadelphia Inquirer runs a story about the interference to non-commercial FM stations caused by satellite radio receivers. By this time, it is common knowledge that the default frequency on many of those receiver modulators is 88.1 MHz, much to the dismay of stations like KKJZ in Long Beach. Mike Starling, NPR Director of Engineering and Operations in Washington, promotes using 87.9 MHz as a default frequency—understandable in light of the fact that many, if not most, of these mini-transmitters come equipped to transmit only on non-commercial frequencies at the lower end of the FM band.

March 29, 2006 – Bob Gonsett writes a detailed letter to Sirius Radio Public Relations officers, with copies sent to various FCC contacts. In it, he asks that the satellite radio companies provide proof that they have received from the FCC a specific waiver that allows them to market satellite radios with FM modulators, “intentional radiators,” operating outside the FM broadcast band on 87.7 and 87.9 MHz.

March 30, 2006 – TV Technology magazine, in Doug Lung’s RF Report, highlights the FM modulator issue as a result of correspondence with Fred Lass, director of engineering at WRGB channel 6 in Schenectady, N.Y. Doug names the names of several modulator manufacturers that advertise illegal modulators and clarifies the FCC rules regarding continuous intentional radiation either misunderstood or ignored by those manufacturers. Doug reveals that Lass has notified the FCC Office of Technology about these transmitters. Lass tells Lung, “All that is required to find [illegal transmitters] is to do a Google search of ‘87.9 MHz’ to get a list of manufacturers and retailers selling these devices in the U.S.”

April 8, 2006 – Bob Gonsett “gets the ball rolling” by filing a complaint with the FCC in Washington against Sirius Satellite for incorporating 87.7 and 87.9 MHz into the intentional radiator mini-transmitters that are built into many Sirius consumer satellite receivers. He chooses to focus the filing on a single high profile case in order to simplify the process, shed light on the problem, and hope that the FCC would itself broaden the investigation.

April 27, 2006 – XM Radio files an 8-K form with the SEC in which it reveals to investors that it has received an inquiry received from the FCC OET on April 25 regarding the emissions of the Delphi SkyFi2 radio. The company states that it is making an internal review and anticipates “responding to the letter shortly and cooperating fully.”

May 8, 2006 – Bob Gonsett posts on his CGC Communicator an anonymous comment from a Los Angeles FM broadcast engineer favoring modulators operating below the FM band. “My feeling on any small transmitter for an XM, Sirius, HD or MP3 players is that they SHOULD use these out of band frequencies. Currently, FCC Rules do not allow this, but the situation deserves careful examination and consideration. Given the interference these devices cause to mobile on-channel reception of legitimate stations, we should give them out of band authorization (but not above 107.9 MHz). As a user, I cannot find a clean channel to use in Los Angeles for my XM receiver. As a licensee, I would not want them on my channel.” A sort of spectral NIMBY statement, but who wants mass transmitters on his frequency?

May 16, 2006 – Reuters reports that Audiovox Corp. suspends shipments of its Xpress Model XMCK10 XM satellite radio receiver after the FCC says the unit “did not comply with either operating bandwidth or related emission specifications.”

May 30, 2006 – XM Radio files another Form 8-K with the SEC in which it reveals to investors that it has suspended marketing of radios made by Delphi and Audiovox in order to comply with an inquiry received from the FCC on April 25. XM says it will modify the radios in question and submit them for Part 15 compliance testing. “We plan to have modified devices shipping to retailers in the near term.”

May 31, 2006 – Orbitcast.com quotes Sirius Radio EVP/CFO David Frear as saying that “all SIRIUS Satellite Radio receivers are in full FCC compliance. Some letters were sent regarding some Sirius devices that were out of spec. Frear stated that they then went to the receiver manufacturers and took care of the problem a while ago. All SIRIUS Radios are in full FCC compliance. Case closed.” Phewww.

Like the Whac-a-mole amusement at your local Chuck E Cheese, getting a couple of vendors to change their ways through FCC inquiries will inevitably result in another vendor producing a replacement product. After all, consumers demand a convenient way to transfer audio without wires. And none of this activity has yet dealt with the multitude of transmitters out there designed to transmit Apple iPod audio over FM. Some of those mini-transmitters are reported to put out suspiciously high signal levels. The work continues.