[AMPS] RE: Re: Re: Mission Impossible

Peter Chadwick Peter_Chadwick@mitel.com
Wed, 8 Mar 2000 09:23:49 -0000


Jan asks;

>You say below that signals was clean but distorted due to too much speech
processing.How can a signal be clean and distorted at the same time?

By 'clean', I mean not excessively wide - or, if you like, the occupied
bandwidth is correct for the voice modulated single sideband signal.
Distortion in stages prior to the final band limiting signal filter (we are
talking filter exciters here, not phasing or third method or DSP generators
using Hilbert transforms unless a band limiting filter follows the speech
processing) doesn't broaden the signal.

Of course, a receiver with reciprocal mixing problems will show an SSB
signal to be wide, no matter how much attenuation is used in the antenna
input, because reciprocal mixing has a linear (i.e. dB for dB) relationship
with input signal.

73

Peter G3RZP




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