[opendtv] Re: News: Britain's "FCC" Sees The End Of The FM Radio Road

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Tue, 28 Nov 2006 10:29:22 -0500

Craig Birkmaier wrote:

> Hmmmmm...
> When you move to an infrastructure that can deliver massive amounts
> of bits to fixed, mobile and portable receivers, at some point you
> realize that separate services for radio, TV and data are redundant...

Actually, I think their point is that the function of FM radio would be
replaced by DAB, which uses a different slice of spectrum. The piece did
not say that DAB spectrum would go to anything else. Here's the quote:

"The potential phasing out of FM radio has been pushed to the front
burner of Ofcom's agenda **following the rapid growth in digital

Ditto with AM radio, since DAB also replaces that. They are not saying
that radio and TV would use the same spectrum. They are instead making
the point that DAB obsoletes AM and FM radio, and DAB uses a separate
right of way, which makes AM and FM spectrum available to other uses.

However, I read some Ibiquity blurb that claimed that other countries
were also looking at IBOC, because it uses the same spectrum as AM and
FM radio. Don't know if this is the case (that other countries are
interested). But it comes out to the same thing. Either assign L band
spectrum to radio, or keep radio where it is and use L band for
something else.

As to your point about common use of infrastructure, to me, it's already
the case. Radio uses VHF just like TV, but far less of it, is expected
to be very robust, and can afford to be much less spectrum-efficient
(and thereby more robust) than TV. High quality TV needs lots of
bandwidth, and therefore is typically required to be more efficient in
how it uses spectrum than radio, which also makes it less robust. TV to
handheld devices is something else again, more like radio.

So this just means that different modulation schemes are used in
essentially the same VHF and UHF parts of the RF spectrum, to meet the
different requirements. So this is the common infrastructure.

No particular reason why radio couldn't use more of the TV spectrum, or
vice versa, except that TV has little to gain if it could share the FM
radio spectrum. The FM spectrum would provide only three extra 6 MHz
channels to TV. On the other hand, radio has something to lose if all
the TV spectrum were available to it, in terms of simple and effective
antenna designs. It's more difficult to make antennas that work
efficiently over a broad range of frequencies.

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