Barry,

The answer to to your question is yes and no.  When you add noise to an
analog signal the quality of the signal gradually gets worse the more noise
you add. With a digital signal via a modem the same sort of thing happens
but since the noise can affect any bit of you data there can end up being
large errors in the value represented by the data for even a small amount
of noise.  The big advantage of digital communications is that it is
possible to add error detection and correction to the data being sent.  You
end up sending more data to allow for correcting errors but the net result
is an almost error free signal.

Jim Hannon






barry lotz  on 07/25/99 09:12:41 PM

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To:   PSN-L Mailing List 
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Subject:  Re: seismic telemetry & VBB




Sean Thomas & David
   Thanks for your response. Does the noise immunity of digital signals
still
apply at radio frequencies? I was thinking of modems vs transievers.

    Regards
    Barry





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