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VE2HAR > MT63 09.03.05 15:33l 87 Lines 2944 Bytes #-7499 (0) @ WW
BID : 2102SENTTO
Read: GUEST
Subj: Re: [MT63] MT63 Implementations
Path: DB0FHN<DB0THA<DB0HDF<DB0ERF<DB0MRW<DB0WUE<DK0WUE<7M3TJZ<ON0AR<VA2HAR<
VE2HAR
Sent: 050309/1310z @:VE2HAR.#MTL.QC.CAN.NOAM Laval #:40748 $:2102sentto
jhhaynes@earthlink.net wrote:
>Well I can understand the concern. MT63 has forward error correction, but
>sometimes condx are bad enough that it can't correct the errors, and then
>you maybe need ARQ to make it try again. Although it may be that when
>FEC can't correct it then the band has gone out and attempting to ARQ
>would be futile.
>
>
>
Exactly. My experience is that I can copy 100% solid a signal that I
can't see on my waterfall display. If it drops lower I can't copy at
all, and ARQ would just automatically try to do it again and again.
Pactor has ARQ and it tries about 10 times and then quits,
>Another possibility would be to marry MT63 with ALE, so that when you
>don't get through in the forward path you are looking for an alternate
>frequency where things are better.
>
>I see too that there is a new protocol called SCAMP under development.
>I haven't really been following it, but I gather the intent is to get
>away from proprietary things like Pactor for the Winlink crowd.
>
>There are Yahoo groups on SCAMPprotocol and oliviadata in addition to
>the MT63 group. You need to be looking at all those.
>
>Seems to me it would be rather hard to adapt MT63 to ARQ, because of the
>rather long turnaround time (that is a consequence of the powerful FEC)
>
>I have some experience with Clover - the original Clover, not Clover 2000.
>I don't know how it compares with some of these other things like MT63
>in ability to get the message through. It is an ARQ plus FEC system.
>In my experience - and maybe I don't have the parameters set up
>optimally - it sometimes gets stuck trying to send a long block when
>conditions are so bad that the block will never get through; and it
>just keeps resending and resending the long block instead of breaking
>it into shorter blocks that have a better change of getting through
>unscathed.
>
>
>
Pactor has two baud rates, 100 and 200. When the going is tough it
switches to 100 baud and keeps trying.
>I don't pretend to any deep knowledge of all this protocol stuff - I
>just play with what's out there. And I have little or no personal
>interest in transmitting files; would just like to be able to have a
>conversation.
>
>
>
72 karl
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