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From: witkowsk@optilink.UUCP (Dave Witkowski)
Newsgroups: comp.dcom.modems
Subject: Re: Capacity of a Channel (Was: Inexpensive 9600 baud modems)
Message-ID: <4986@optilink.UUCP>
Date: 11 Dec 90 18:52:35 GMT
References: <1990Dec10.162413.13959@sparrms.ists.ca>
Organization: Optilink Corporation, Petaluma, CA
Lines: 19

From article <1990Dec10.162413.13959@sparrms.ists.ca>, by mb@sparrms.ists.ca (Mike Bell):
> My book on information theory gives Shannon's result as:
> 
>     Channel Capacity = Bandwidth * log2( 1 + SignalPower/NoisePower )
> 
> Anybody know what Signal/Noise ratios are likely to be found on
> normal phone lines? This would give an indication of the practical
> limit to modem speeds.
>

Idle channel noise per BellCore TRY-0064 is:

20dBrnC for C-message weighting
39dBrn for 3-KHz flat response

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