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VE2HAR > MT63 18.03.05 15:38l 122 Lines 3258 Bytes #-7294 (0) @ WW
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Subj: Re: [MT63] Digest Number 865
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Sent: 050318/1417z @:VE2HAR.#MTL.QC.CAN.NOAM Laval #:43661 $:46778sentto
>
> Hello John,
>
> >> With respect to the mode, well I am not convinced that MT63 works
> better than MFSK under really poor conditions, although the baud rate
> is higher. <<
>
> Forgive me for sticking my aging brain in here, but I couldn't resist.
> In regard to emergency data communications, when all is said and done,
> when conditions are truly abysmal, there just ain't no substitute for
> the old-fasioned AMTOR ARQ mode.
>
Norm,
At a 0 dB SNR on a poor CCIR channel, AMTOR ARQ has ZERO throughput but MFSK16
will have full throughput.
While I don't know how MFSK16 works with WMix or other Windows MFSK16
applications, gMFSK seems to allow you to send a file when MFSK16 is selected.
Someone may want to confirm this.
But the fact is that MFSK12 will copy down at -10 dB SNR as well as it does at a
+10 dB SNR.
> When done correctly by someone who knows how to use that mode, IMHO
> it can't be beaten for accurate, error-free communications. When you
> realize that the SITOR specs (CCIR Recommendation 476 et al) that
> really govern AMTOR call for NOT MORE THAH THREE CHARACTER ERRORS IN
> ONE HUNDRED THOUSAND CHARACTERS, it is hard to find another SCD mode
> that can do as well under abominable HF conditions.
MT63 is 99% error free down at a -10 dB SNR on a poor CCIR channel. Typing/
trasncription errors in emergency communications are 2-4%.
As G4HPE has shown, at a -10 dB SNR, MT63 will have about a 1% error rate.
My choice would be MT63 or if more robustness is needed, then MFSK16.
>
> After all, what difference does the baud rate make when the link is
> repeatedly lost?
This is true...however, remember that the more robust the mode, the better then
chance of getting you data through "when conditions are truly abysmal".
>
> Just my not-so-humble opinion based on a few long decades of working
> with this stuff.
Yea, I know...I"ve been doing EComms since the Hurricane season of 1961 and with
the Air Force starting in 1967.
Of course Texas doesn't have as many hurricanes as Flordia.
I was involved with Hurricane Andrew while with the Air Force. I was supporting
the NDMS Aux DOC in Oklahoma City during Andrew.
Best Regards,
Walt/K5YFW
>
> 73,
>
> Norm Sternberg W2JUP - NNN0TOA
> Plantation, FL
>
> (TS-2000/PK-232/DSP-2232/ATU-1000/GAP Titan-DX)
>
>
>
> << Try MT63 on 80m - great fun!>>
>
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