On Thu, 30 Sep 2004 19:22:59 -0800, Robert Orban
wrote:

Pearce Consulting
http://www.pearce.uk.com


Don -- I'm sorry you're cross with me. However, I presume that you
understand that the FM channel does not have an infinite signal-to-noise
ratio. Eliminating all forms of protection processing will cause many
potential listeners of a given radio station to be unable to enjoy that
station because quiet parts of the program are contaminated by noise. "Turning
up the volume control" also turns up the noise and hence, does not address the
problem.

In the days of monophonic FM and outdoor aerials, this was less of a problem.
However, FM stereo introduced a noise penalty of approximately 20 dB, and few
people use outddor aerials anymore.

All DSP-based FM Optimods, BTW, offer the ability to configure the unit for
various forms of "purist" processing. The most purist of these offers
protection limiting that introduces no compression at all with normal input
levels, and only does the amount of HF limiting and peak limiting necessary to
protect the channel from overdeviation.

Bob Orban

Is there anybody left in the industry with the slightest idea of
exactly how much signal to noise ratio an FM channel actually has? It
has more than enough by many tens of dBs to cope with any pop record
released in the last twenty years. It also has vastly more than any
piece of vinyl *ever* released, and it has plenty enough for any
classical recording. So the lack of dynamic range argument is a
non-starter.

As for protecting channels from overdeviation, it is a regulatory
requirement that transmitters contain such protection - they don't
need Optimod for that, and anyway that is what the engineer is for.

No, Optimod is a tool seized upon by cheap and nasty radio stations
(and yes, I know that is most of them) for making themselves as noisy
and obnoxious as possible in order to stand out and appeal to the
lowest common denominator in the market. Now I'm sure that is a plan
of sorts, and I can't knock it. But never try to claim that it has
anything to do with quality. If you want quality you just leave out
all these extraneous bits - radio does not need them.

d
Pearce Consulting
http://www.pearce.uk.com