In article ,
dave wrote:

There's no need for a separate tower. Depending on the linearity and
headroom of the transmitter plant you could conceivably get by with just
a new exciter and new monitor.

That's a misconception. All pre-IBOC analog transmitters are non-linear
by design for efficiency reasons. They cannot pass an IBOC digital
signal, which consists of multiple carriers. A specially-designed linear
transmitter must be used.

I can see from reading these threads that many people are under the
impression that IBOC is nothing more than some sort of subcarrier
superimposed on the main channel. Unless the station is using a combo
analog/IBOC transmitter, the outputs of both analog and IBOC transmitter
must be combined by a device that discards 90% of the IBOC signal and
10% of the analog signal. All of that stuff costs money, as does the
increased air conditioning requirement, and power (particularly that
which is burned off as heat). In many installations (and I've seen
dozens...I wonder how many of our pontificators have even seen one), the
IBOC and analog transmitter sit side by side...and they're about the
same physical size.

My point is, adding IBOC to a station is far more complex and costly
than putting some 4-unit device in the rack and hooking it up. A "new
exciter" doesn't do it.

Oh, and don't forget the studio, the new digital STL, monitoring
equipment, and the fact that HD equipment currently in the field is
notoriously unreliable. Fortunately, most stations don't care that much
because their three HD listeners don't phone in to complain.

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