🚀 go-pugleaf

"Robert Orban" <donotreply@spamblock.com> wrote in message
news:KJudnWNZ2vjHGpjanZ2dnUVZ_vumnZ2d@giganews.com...
> In article <Crqdndk7urPjlp3anZ2dnUVZ_g-dnZ2d@championbroadband.com>,
> me@champmail.net says...
>>
>>
>>
>>"SFTV_troy" blabbed:
>><... this new receiving technique would not improve the sound
>>> (it would still be limited from 100-6000 hertz), but would only reduce
>>> interference.
>>>
>>At least in the States, AM & FM broadcasting is limited to 50 Hz to 15KHz.
>
> There is no low frequency limit for either AM or FM; 50 Hz was the minimum
> performance standard that would meet the now long-deleted FCC Proof of
> Performance measurements.
>
> The effective HF limit on FM is about 18.5 kHz; this leaves a +/- 500 Hz guard
> band for the stereo pilot tone. Again, 15 kHz was the minimum spec that would
> pass a Proof of Performance, not a limit on bandwidth.
>
> Currently, the legal FCC-mandated HF limit on AM in the US is a hair less than
> 10 kHz, which almost completely protects second-adjacent stations from
> interference. This was changed around 1990 as a result of work done by the
> National Radio Systems Committee (NRSC). More recent work by the NRSC has
> indicated that 7 kHz is probably the optimum compromise between causing
> interference and loss of audio quality on typical AM radios (which are down 3
> dB at about 2.6 kHz). However, limiting bandwidth to 7 kHz is voluntary.
>

Robert,

Was AM radio ever allowed audio to 15 KHz?  I read many years ago that it was, perhaps 
before the NRSC recommendation was adopted by the FCC.  I presumed that the stations either 
were allowed to overlap 5 KHz (doubtful), or that stations in a given area were separated by 
at least 30 KHz.
-- 
Regards from Virginia Beach,

Earl Kiosterud
www.smokeylake.com