• KZND-LP is a licensed LPTV. Every TV station has an FM audio transmitter. KZND-LP, ch. 6, has FM sound on 87.74 MHz. We operate it with regular FM stereo as a commercial radio station. See technical details here.
• KZND-LP has 920 watts Horizontal and Vertical ERP of FM Audio.
• KZND-LP is located .9 miles from my home.
• If KZND-LP were an LP-100 LPFM station it would only have 20 Watts ERP due to its height above average terrain.
• KRUA-(FM) is a student full service FM station on 88.1 MHz licensed to the University of Alaska with 150 Watts located about 20 miles from my home.
• 88.1-87.74=360 KHz. Required frequency spacing between an LPFM and a regular FM is 600 KHz. KZND-LP is only 6/10 of that required under LPFM rules.
• KZND-LP is very close and line of sight to my home.
• KRUA is distant, and lower power, and not quite line of sight. In fact, KRUA is not crystal clear on the best of radios at my home. On inexpensive radios, KRUA cannot be heard, regardless of KZND-LP.
• The radio you can listen to is an average quality home radio. A JVC RX-220. The antenna is the wire draped over the lamp.

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*EDITORIAL*

Exposing a radio to many strong FM signals, as is common in most of the US, can degrade reception on lower quality FM radios to the extent that measured impact of an LPFM signal on one standard FM signal has little practical meaning. For more info, see my guest commentary in Radio World .

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Multiple Signal Overload

Most tests by the FCC, CEA, NAB and others were single interfering signal. Multiple strong signals have more effect on a receiving system than one. One study that reveals this effect was a Canadian study of interference to TV sets from FM radio stations. I have posted this study. See Interference to US TV channel 6 from FM & NCE-FM broadcast. Study by Canadian Department of Communication, Ottawa, 1969 on our link list page. A good example is this graph, Figure 8a comparing picture degradation from one or two undesired FM signals. A fair study using multiple interfering FM signals far from the desired FM station frequency should prove that "inexpensive" FM radios already suffer serious interference from high power FM stations, and that inclusion of a few LPFM signals would not significantly increase interference. If one argues that additional interference caused by LPFM should be prevented, then one must also argue that power increases, site moves, new full power FM and translator stations should be prohibited. LPFM stations will be a minor problem compared to incresed full power FM. For this reason, I believe no further study is needed, as no one proposes freezing improved or new full power FM.

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PICTURES OF KZND-LP SITE AND FM RADIO USED FOR REAL AUDIO FEED

Click on an image for full resolution view.
Above is a view from my porch of the KZND-LP transmitter site. The radio is in the photo on the right. Notice the FM antenna is draped over the lamp. I do have to fiddle with the antenna wire to get good reception, but this is no different with KZND-LP on or off the air.

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Radios that do not receive KRUA at my home

I have 4 inexpensive radios that do not receive KRUA. Here are photos of two of them. Turning KZND-LP off the air does not make it possible to listen to KRUA on these inexpensive radios. My point is, that lab tests have not subjected inexpensive radios to the multitude of signals that exist in real life. There may be a few places where an LPFM may interfere with reception on inexpensive radios like these, but usually real world conditions would have ruled out reception before an LPFM hit the air.

The above Sony is so overloaded by local signals, it cannot receive a 100 kW 91.1 FM 18 line of sight miles away due overloading by many strong local signals.