Another engineer has thoughts


Thoughts about directing some TV space to FM 

I was pleasantly surprised to read about the proposal from engineer John Mullaney to convert the bandwidth in TV Channel 6 (and 5?) to FM Radio broadcasting. This is an idea I have privately been kicking around for a couple of years now. Mr. Mullaney’s proposal, though, is even more ambitious than mine, by his including the Channel 5 spectrum as well.

My idea involved only using Channel 6 (82-88 MHz), with these ideas in mind:

1. Removing the spectrum now used by Channel 6 for TV broadcasting would, once and for all, remove the conflict with FM Channel 253 (98.5 FM).

2. Use the lowest portion of the now-Channel 6 frequency, at 82 MHz, for five LPFM-only frequencies at 82.1, 82.3, 82.5, 82.7 and 82.9 MHz. Incumbent LPFM stations would be mandated, and given a specified amount of time to comply, to migrate to the 82 MHz frequencies. Moving the LPFM stations to this new bandwidth would eliminate concerns about interference to existing, full-power FM stations, and would open up hundreds (thousands?) more LPFM frequencies.

3. Use the 83 MHz frequencies, at 83.1, 83.3, 83.5, 83.7 and 83.9 MHz, as translators for AM daytime-only stations, local (AM Class C) stations, and Class D AM stations that are required to power down significantly after sunset. These 83 MHz translators would be capped at 250w ERP. As with incumbent LPFMs, the few AM stations that are presently using FM translators at night would be mandated to surrender their current FM translators and move to one of the 83 MHz frequencies.

4. Finally, use that part of the Channel 6 spectrum from 84.1 MHz to 87.9 MHz for additional, full-power NCE FM stations. For both channel spacing/interference reasons, and to allow a greater number of NCE licensees, I would recommend that these new stations be limited to 50kW ERP (FM Class B or C2). Incumbent NCE stations that are currently broadcasting above 50kW ERP would continue to do so. And again, NCE broadcasters that are currently using the "non-reserved" band, from 92.1 to 107.9 MHz, would be required to migrate to the new and existing "reserved" band (84.1 MHz to 91.9 MHz).

NCE licensees now operating in the "non-reserved" band would be the first group to be moved to the expanded "reserved" band, for reasons of "cleaning up" the non-reserved band, eliminating short-spacing, and allowing for more commercial FM stations, for which there is still a huge demand. Next in order to be moved would be incumbent NCE stations, now operating in the existing "reserved" band ( 88.1 MHz to 91.9 MHz), again for purposes of cleaning up that band and eliminating short-spacing. Remaining frequencies in the expanded "reserved" band would be available for new NCE licensees.

Including the now-Channel 5 bandwidth, as Mr. Mullaney proposes, would greatly increase the possibilities for FM broadcasting even more. Whether a new FM service would include only the current Channel 6 bandwidth, or include the present Channel 5 bandwidth as well, would result is some very exciting, new prospects for FM broadcasting.

Robert E. Lee
San Diego, CA