In article ,
Woody wrote:
Rubbish!. AM radio was downgraded by reducing it's bandwidth from 9kHz
to
4.5kHz betwen the 1930s and the 1960s.


Could you qualify that please?
AM radio, AFAIK, has always has an audio frequency response limit of
4KHz which means it needs an RF bandwidth of 8KHz. The station spacing
is thus set at 9KHz to (theoretically) leave a guard band between
stations. In practice for most domestic radios this is of little
consequence as it would be nigh impossible to hear two stations on
adjacent frequencies - something that would be possible on a
commercial/professional receiver with a much more closely controlled
passband.

Not so - the changes making the 9 kHz an international standard came in on
IIRC the early '70s. When R1 started up in the London area the 247 metre
transmissions had a bandwidth exceeding 12 kHz - the landline feeding that
transmitter was also wide band. With a good AM receiver the frequency
response didn't sound much different to FM when R1&2 did simulcasts.

--
*Nostalgia isn't what is used to be.

Dave Plowman London SW
To e-mail, change noise into sound.