Re: [Phys-l] an all-too-predictable blackout

["John Clement" <clement@hal-pc.org>]

The standard telephone bandwidth has always been fairly small, around 3kHz
or so,  If you want bandwidth up to 10kHz or so you had to pay extra.  Also
the low frequencies below about 400Hz are removed.  It may be that
occasionally you could get a line without the usual filtration, but I never
remember having one.  Consumer Reports has a complete report of phones, and
the problem is basically that the quality is not built into the receiver or
the mike.  They rate both of these.  They can't reduce the bandwidth more
without severely impacting intelligibility.  But it is possible to
artificially regenerate some of the overtones to give a more natural sound.
The missing bass is gone forever.

John M. Clement
Houston, TX


> I wonder if the sampling rate used to squeeze the phone calls 
> into the available bandwidth is hampering the fidelity. I 
> don't know what that is, but maybe our resident Bell Labs guy 
> can help with some technical info.  Better fidelity would 
> require better sampling which would reduce the # of 
> simultaneous calls on a channel.  That means more 
> infrastructure/cost per call.