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Airwaves: May 28, 2010

Digital problems

Two complaints have been officially filed with the Federal Communications Commission regarding interference from digital broadcasts.

The first one involves KATY (101.3 FM) in Idyllwild; owner All-Pro Broadcasting claims that KRTH (101.1 FM) is causing continuous detrimental interference with KATY within KATY’s licensed broadcast area. In addition to the filing, All-Pro submitted a recording of actual interference made while traveling in a vehicle.

Interestingly, the filing has nothing to do with the recent rule change allowing stations to increase their digital power. According to All-Pro, the interference actually dates back to June, 2007, when KRTH went full-time with the HD digital system. KRTH, they say, has been unwilling to work with the engineers to solve the problem, leading to the decision to file an official complaint.

Likewise, KMLA (103.7 FM) in El Rio has filed a complaint in regard to interference from neighboring KOST (103.5 FM) for much the same reason. Like KRTH, KOST still has not increased digital broadcast power.

One of the obvious questions is: why now? Why not before? I don’t have a good answer. But I do know that both KRTH and KOST operate at a higher analog power than would be allowed if they applied for their signals today. Their high-power status was grandfathered in when later rule changes cut the power for their station class.

Why is this important? Allowed digital power is a set fraction of analog ... the higher the analog power, the higher the digital power. New rules allow stations to go from a fraction of 1/100 to 1/25. Perhaps these filings are a pre-strike to make sure the stations stay put, as far as broadcast power goes. Or perhaps they finally got fed up.

My own question is: what does digital interference sound like on FM? While the interference on AM is easily heard -- it sounds like an old-style modem “whoosh” or white noise when you tune off just off a digital AM station, and the way that AM works, that noise gets picked up easily by the radio.

My understanding is that FM is quite different, that you can’t actually hear the interference. What can theoretically happen is that distant stations you used to hear are suddenly gone, as the interference tricks the FM receiver to mute a formerly heard station. I have yet to experience that phenomenon, however, but that doesn’t mean it isn’t happening.

Perhaps both KATY and KMLA are no longer strong locally due to the interference, and radios are muting them out at times. Certainly the two stations wouldn’t go through the trouble to file complaints if nothing was happening.


Cal State Long Beach has been without a student-run station ever since March, 1981 when they bought KLON (now KJAZ, 88.1 FM) shut down student-run KSUL, and destroyed, in one fell swoop, the entire radio-television department on the campus.

Recently students got together to launch K-BEACH, a student-run internet station that can be found at I happened to be visiting the site the other night and noticed a little blurb on their main page that is quite remarkable: it seems that KJAZ has finally agreed to let K-Beach to broadcast on a digital HD side channel.

It’s about time. A school should not be allowed to hold a broadcast license if students are not running the station; KJAZ has no students involved at all. Giving students an HD side channel is the least they can do for K-BEACH, and they should be doing it now, for free, rather than making students fundraise to get the equipment and connections.

Of course I still hold a grudge for them shutting down KSUL in the first place ...


Copyright © 2010 Richard Wagoner and Los Angeles Newspaper Group.

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