> 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. 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.
WOR in New York has been experimenting (yes, even broadcasters are allowed to
experiment just like hams once were) with digital IBOC
but the jury is still out on whether it can be a viable mode given sky wave
propagation, fading, noise & interference, etc. The
IBOC receiver goes into an analog "blend" mode when the BER reaches a
pre-determined threshold. I haven't heard it, but I can only