"Stephen M.H. Lawrence" wrote in message
hlink.net...

"Frank Dresser" wrote:
| 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.

I thought that the NRSC standard is 7.5 KHz?

I've got an old Popular Electronics magazine article around here somewhere
which claims the the 20 kHz max AM bandwidth. The author seemed
knowledgeable, but I also have a couple of textbooks which claim a 10 kHz
max AM bandwidth. I don't trust the textbooks, so I searched the FCC
website.

I came up with:

3. Sound Broadcasting

Sound broadcasting, double-sideband..

BINFn/INF=2M, M may vary between 4000 and 10000
depending on the quality desired

This defination was among a group above the FCC's formulas:

BINFn/INF = Necessary bandwidth in hertz

So, if I'm reading this correctly, the necessary bandwidth for standard AM
will be twice the audio bandwidth, which must be between a minimum audio
bandwidth of 4000 Hz and a maximum audio bandwidth of 10,000Hz.

This is from:

http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=47&PART=2&SECTION=202&YEAR=2001&TYPE =TEXT



At any rate, a practical bandwidth of 10 KHz would be
a nice improvement.


Yeah, I think few broadcasters get near the maximum. But, considering the
average AM radio, why bother?



Frank Dresser