RadioBanter - View Single Post - FM Broadcast band as we know it going away?

February 18th 04, 07:43 PM

(Robert Hovland) wrote in message ...
Dear Newsgroup,

Does anyone know the latest info about what is going to happen to the FM
band when the FCC forces all of the VHF television stations to give up
their broadcast band and switch to the new freqency allocations for
digital TV? As you may or may not know, the FM band is located in between
channels 6 and 7, I believe, and I would be surprised if the FCC would
leave the FM band alone when the TV stations get out. They want to
auction these soon-to-be-obsolete TV channel frequencies off to the
highest bidder.

This is an absurd notion, based on a lack of understanding.

There is a big chunk of spectrum between channels 6 and 7.

FM broadcast band 88-108MHz

The aero band, 108 to 136MHz or so.

Whatever is between 136 and 144MHz

2 meter amateur band, 144 to 148MHz

"Public service band" 148 to 174MHz
(I've lumped a lot here; paging, fire and police (at least in the
old days, MURS, the VHF marine band, the weather service broadcasts,
business use, etc).

Then comes channel 7.

So if they took the FM band away, there would still be a large chunk
there.

Take note that there is a 6MHz gap, a whole channel, between channels
4 and 5, which actually would be "in the way" more than the FM
band clustered with those other services that will not move.

What you also miss is the amount of spectrum that would be released
if TV vacated from the VHF frequencies (which the other posters
have indicated will not happen). 72MHz would be free, which is
in fact a massive amount of spectrum. TV is the widest bandwidth
signal commonly used, and you can fit an awful lot of stations in the
6MHz bandwidth used by one channel, the moreso now as schemes have
come into play to make better use of the spectrum for two way
communication.

So if the tv channels were released for other uses, a measly 20MHz
for the FM band is nothing.

Even if none of this was true, except for TV there is very little
need for continuous spectrum. So six MHz here, and six MHz there
will result in 12MHz available, and they do not have to be adjacent.
What we have seen is TV getting in the way. They were allocated over
fifty years ago, when radio was still relatively unused. They took
up large chunks of the VHF spectrum, no other service has so much
allocation in the 30 to 300MHz range, and so whatever came later
had to be fitted into whatever segments remained. Once the spectrum
was full, there was no more space to put anything, even though in any
given location there was always space lying empty, since no area has
all tv channels in use. The other services don't need so big chunks,
but TV is using any available space.

In other words, even if the tv channels were vacated for other uses,
there is no reason to lump the FM broadcast band with them.

Michael