Who Needs LPFM? - Why Not Just Expand the FM Dial?
At last Tuesday's FCC meeting, the Commission adopted a controversial order, over the objection of two Commissioners, that could limit the processing of some applications for improvements by some full power FM stations, and would restrict translator applications, all in the name of encouraging Low Power FM (LPFM) stations to provide outlets for expression by groups that cannot get access to full-power radio stations (see our summary of that action here). In recent weeks, two ideas have received some publicity providing an alternative outlet for these prospective local broadcasters - and both provide a simple solution (one more immediate and ad hoc than that other), but both leading to the same result - why not just extend the FM band by using TV channel 6?
The current FM band begins at 88.1 MHz, a channel that is actually immediately adjacent to TV Channel 6. The FCC has for years restricted operations of noncommercial FM stations (which operate from 88.1 to 91.9 on the FM dial) in areas where there are Channel 6 TV stations in order to prevent the radio stations from creating interference to the reception of the TV stations. That's while you will often find fewer noncommercial stations, or ones with weaker coverage, in communities that have TV Channel 6 licensees. TV stations use an FM transmission system for their audio. Thus, you will also find that most FM receivers (especially ones without digital tuners) will pick up the audio from TV channel 6 if tuned all the way to the left of the dial. The short-term solution to expanding the FM band came from one broadcaster who noted that fact.
In recent weeks, a new FM station has surfaced in New York City - one which is not really an FM station at all, but instead a TV channel 6 operation being programmed like a radio station to emphasize the audio that can be picked up on FM radio dials. Any FM station in New York would have easily cost many tens of millions of dollars to buy - so instead a new radio outlet was created by taking this low power television station, previously targeted to a narrow ethnic audience, to reach a much broader radio audience in the City. A unique solution to the search for a spot on the crowded radio dial - and one that will not disappear in 2009 at the end of the digital conversion, as LPTV stations currently have no mandatory digital transition deadline.
As a longer term solution, why not just take all of channel 6 and use it for FM operations? That proposal was one that was advanced by consulting engineer Jack Mullaney in Comments recently filed in the digital television proceeding. In his comments, Mullaney advocates the use of channel 6 (which has not been used by the FCC for digital operations of television stations to avoid interference to noncommercial FM stations, except in a few isolated cases where no alternative digital channel was available, ) for FM operations after the digital television transition has been complete. As set out in Mullaney's comments, this could increase the FM band by 30 channels (there currently are 100 FM channels), which could create enough spectrum to allow for channels set aside for specific uses like LPFM, without having to worry about interference to full power stations. Or channels could be set aside just for FM translators. A section of the band could even be reserved for "pirate" radio - allowing anyone to start a radio station without an FCC license, provided that they stay on-channel and observe specific power limitations.
These innovative solutions to the current perceived scarcity of FM channels would be more advantageous than the Commission's current attempt to repeal the laws of physics by cramming LPFM stations into the existing band without displacing or otherwise interfering with other authorized users - a seemingly impossible proposition. The proposal has been made - how will the FCC react to Mr. Mullaney's suggestion?
> innovative solutions to the current perceived scarcity of FM channels
And we would add another solution, at the URL above.
http://www.26mhz.us
Yes innovative, but simply expanding the spectrum of available channels replicates a problem that also plagued even the current TV channel spectrum up to and well into the 1960's: It's similar to the UHF quandary in that the existing equipment now (as with UHF in the early 60's) doesn't support the spectrum sufficiently below 87.7MHz on most devices, and certainly doesn't support going to 82MHz.
Given that the FM band in the US has been 88-108MHz for 60+ years, and the plethora of equipment in use (note: HD Radio doesn't render the existing equipment useless, but also doesn't take advantage of the multicasting features) isn't going away anytime too soon. Any station that would theoretically be assigned as sub-87.7MHz frequency would languish due to the lack of availability of good tuners in this country. The only option might be in securing Japanese/Asian-spec equipment where the 76-90 spectrum is available, which creates an inverse problem.
Don't get me wrong -- I love the idea of this, but fear that adoption would take a decade and still be as iffy as HD Radio is today toward adoption (how many factory-installed vehicles have it now). Expanding the spectrum by 30% or 60% would displace 1-2 TV channels in the New York and Philadelphia markets alone.
Except you're wrong- most receivers can receive the 76 MHz - 90 Mhz band by being switched to Japan mode, usually a hidden switch or pop-off resistor.
I am for expanding the FM band. You would have to raise the IF 10.7 MHZ freq.
I have a radio that goes from 76 MHZ - 108 MHZ. I get images that are 21.4 MHZ away.
For example if I tune 77.1 MHZ I hear 98.5 MHZ. The local Osc is 10.7 MHZ above 77.1. 77.1 + 10.7 = 87.8 MHZ
98.5 comes in mixes with 87.8, 98.5 - 87.8 = 10.7 MHZ IF freq. The radio thinks 98.5 is a 77.1 broadcast.