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V.32 / V.34 modem protocol

Discussion in 'Electronic Design' started by ecco, Oct 30, 2007.

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  1. ecco

    ecco Guest

    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.


  2. JosephKK

    JosephKK Guest

    ecco posted to
    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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