At 03:16 PM 04/18/2003 -0400, Paul Christensen, Esq. wrote:
> > damping to let the microphone hear only the "golden tones" of the ham
> > transmitting. AM broadcast doesn't even allow going to 15 KHz.
>Prior to the implementation of NRSC mask in the early '90s, AM Broadcast
>stations had no upper limit.
Well, they did have an upper freq limit spec as I recall. It was 7.5
kHz. When we ordered BC quality loaded lines
from telco years ago it was 7.5 kHz for AM and 15 kHz for FM. I can see
the correlation now with the later
NRSC roll-off filters. Before NRSC the 7.5 kHz spec was probably enough
protection for adjacent stations.
>The NRSC mask now effectively
>limits the audio passband to approximately 9.5 kHz....and the service
>still sounds poor despite attempts by broadcast stations and
>receiver manufacturers to improve the quality.
AM quality today is really a lot better, with tailored processing and PDM
modulation. (up to +125%)
If the listener has a good quality RX it's not bad.....
And..... for "talk radio," including sibilant sounds, 7.5 kHz (or 9.5)
is more than enough.
(I'm sure the majority are tired of this subject now.... I'm quitting
before the flames arise!) :-)