soundmodem parameter definitions

From: Mike Markowski (tnlgc@uoregon.edu)
Date: Fri Feb 20 2004 - 16:40:37 EET

  • Next message: Tomi Manninen: "Re: soundmodem parameter definitions"

    I have a few simple soundmodem questions that I couldn't
    answer using Google, and I haven't yet dug into the code. In
    soundmodemconfig (using v0.7) I'm trying to get a better
    understanding of the parameters:

            txDelay: is this the delay between asserting PTT
                     and start of data transmission?
                     (My set up with an ICOM 706 MkIIg didn't work
                     until increasing txDelay to 400 ms)

            txTail: delay from end of transmission till deasserting PTT?
                     I'm using the default 10 ms and my aprs UI packets are
                     being received by others.

            slot time: this one confuses me. I know what traditional slotted
                     channels are, but it doesn't make sense that a user
                     would pick the slot length. So I'm guessing this
                     is something different. Is the default of 100 ms
                     reasonable? I used 300 ms for no special reason...

            pPersistence: I assume this is used by the CSMA backoff
                     algorithm. Would I ever want to change the
                     default of 40?

    And on a completely unrelated note, if anyone knows of any packet
    frequencies to use on HF or in southeastern Pennsylvania, please let
    me know. So far I've only been able to use APRS for testing. The
    only other nodes I've found locally are FlexNet BBSes, which I don't
    know much about except that they reply to SABM+ connection requests
    with RR0+ and next with a long packet my soundmodem never seems to
    decode. But maybe that's because my txTail or slot time are poorly
    chosen... I still have a lot to figure out.

    Thanks! I really appreciate all the great help to beginners from
    this list.
            
            Mike AB3AP
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