In article ,
SMS wrote:

No, actually it doesn't. Or at least it usually doesn't require a new
transmitter.

I beg your pardon. In most cases, it does. I do this for a living;
what's your source?

As long as the existing transmitter has an extra 10% of power headroom
to overcome combiner losses, you can do high-level combining and you do
not need a new transmitter (or tower).

Where do you think the IBOC signal comes from? It's called a
"transmitter". And for your information, a low-power transmitter running
in class A (necessary for IBOC) costs about as much as a much larger
class C transmitter. Remember, 90% of the IBOC power is thrown away, so
you need an IBOC transmitter capable of ten times the power you intend
to use.

If you have to buy a new transmitter then of course the cost goes way up
but you still don't need a new tower.

Most people don't have spare IBOC transmitter laying around.

They are not separate systems, either virtually or in reality. No
stations at all would be broadcasting HD if it required separate
transmitters and towers.

You have no idea, do you? Conglomerates **** away money all the time.
Millions of dollars have been spent just in the Bay Area to install IBOC
at the chain stations. The independents can't afford it, and that's part
of the game plan by the conglomerates.

John can answer the question as to how many stations have transmitters
with that 10% of headroom, but apparently many do.

And John will answer that such headroom is a very minor consideration.
The major cost is the IBOC transmitter, the combiner and reject load,
and the iBiquity gear. Don't forget the annual checks to iBiquity.

--
John Higdon
+1 408 ANdrews 6-4400
AT&T-Free At Last