Re: distinguish between fax and speech



VSP wrote:



Could you or anyone else atleast tell me a good online source where i can
read about how the FAX data to be transmitted is exactly coded. 

Again, i am trying to look for a property in this coding that would help
me distinguish it from other transmissions eg some kind of periodicity in
the coded signal etc.


You do not need to know how the fax works to distinguish the fax/modem transmission from the speech. The spectum of the speech rolls down toward the high frequency; the spectrum of the data transmission is basically flat. All you have to do is to weight the high frequencies vs low frequencies.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com

.

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