"nsj" wrote in message
...
Frank Dresser wrote:

Remember that we have 5.5kHz audio bandwidth AM (if that) for domestic
transmissions -- not the wide bandwidth/stereo services you're used to in
North America.


Currently, the FCC limits AM stations to a bandwidth of 20 kHz, or an audio
bandwidth of 10 kHz. Thirty years ago, there wasn't an explicit limit,
stations were required to limit their bandwidth to limit interference.
Given the normal channel spacing of at least 30 kHz in each market back
then, an AM station could go a full 30 kHz if they wanted to. I'm sure at
least a couple of the 50 kW stations here were doing just that, as I could
hear it when DXing stations 20 or 30 kHz away. These stations weren't
overmodulating, they were putting out an excellent signal.

I'm not so sure many stations even go to the maximum allowed bandwidth now.
They do seem to be pre-emphisizing the trebles, though. It sounds shrill on
a wide bandwidth radio, but it seems to be a good comprimise on a normal
radio with a typical IF roll off.

Many US AM MW stations are talkers now. Political talk, Sport talk or just
plain babble. Bandwidth isn't much of an issue. Big US cities will have
several ethnic stations which play music. In Chicago, there's a gospel
music station and a polka station which sound OK. But none of the current
stations sound as good as the stations did back in the musicradio days.

Actually, with the exception of a classical station here, FM radio falls
short of it's fidelity potential, as well. Most of it sounds over processed
and over compressed. It's OK for backround noise. CDs or records sound
better.

I suppose the broadcasters know what they're doing. I'm sure they could get
poor real fast if they took my advice on audio processing.

Frank Dresser

Frank Dresser