V.32 / V.34 modem protocol

Oct 30, 2007 1 Replies
E

Hi, All Please forgive me if this posting should be in another newsgroup.



I am reading about the ITU V.32 and V.34 recommendations. While I have been able to find descriptions of the signal constellations and coding schemes, I have had a tough time finding out information on the communications protocol. Specifically, I want to know how the calling and answering modem keep the dial-up connection alive when neither party has any data to communicate.



If anyone has any info on this (or knows which forum would be a better fit than .design), please let me know.



Thanks.



ecco



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ecco snipped-for-privacy@gmail.com posted to sci.electronics.design:

As best as i understand it, the telephone system treats it like any telephone call (loop start, dialing sequence, connect, continue until no loop[on-hook at either end]). If the there is no data to send the modem may insert nulls or syns or there may be a bare carrier to maintain synchronization and line adaptation. I figure that sending nulls is most likely. It is also possible that a special idle symbol is sent repetitively.

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