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RE: [Q15X25] Re: Status of Q15X25?

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  • Tomi Manninen
    ... MFSK16 is 8-bit clean so there is no reason why binary data couldn t be sent with it. However I don t think a common procedure for doing that exists. MT63
    Message 1 of 33 , Nov 16, 2004
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      On Tue, 2004-11-16 at 21:22, dubose@... wrote:

      > Dropout SNR
      > Mode Best Throughput on a poor CCIR channel Note
      > MT63 200 WPM -5 dB CAn send binary file
      > MFSK16 60 WPM -29 dB Cannot send binday file

      MFSK16 is 8-bit clean so there is no reason why binary data
      couldn't be sent with it. However I don't think a common
      procedure for doing that exists.

      MT63 on the other hand is natively 7-bit only. 8-bit extensions
      exist and a binary file transfer extension also exists (the
      IZ8BLY file transfer method). These extensions are all poorly
      defined, mostly only existing as haphazard implementations
      on different programs implementing MT63.

      Tomi Manninen / OH2BNS / KP20ME04
    • Stewart
      GE, Rick - I guess all I can say is that the proof is in the the pudding and my comments are based on experience, which after should be the ultimate test.
      Message 33 of 33 , Nov 17, 2004
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        GE, Rick -

        I guess all I can say is that the proof is in the the pudding and my
        comments are based on experience, which after should be the ultimate
        test. Incidentally, I would add that we do re-review programs that
        had been looked at previously.

        What has to be remembered is that MARS stations are not concerned
        with going around the world point-to-point. Our nets generally
        involve distances of 200 to 300 miles, give or take, although there
        are nets that do cover a much larger area and can require the use of
        relays to get some stations checked in. Additionally, we are
        essentially using clear channels and formal net procedures, hence we
        are generally not bogged down with QRM, deliberate or otherwise.
        Additionally, we have a number of channels available such that for
        part of the year we will use one frequency for a given net, and move
        2 or 3 or 4 MHz for the rest of the year, recognizing the seasonal
        changes in propagation.

        I have no particular quarrel with your comments about PACTOR.
        However, because it is an ARQ mode, when conditions go south, the
        ACKing and NAKing can really stretch out the time to send a message.
        Taking 20 minutes or more to send one message, even though it will be
        complete, seems to me not to make much sense and certainly ties up a
        frequency unnecessarily.

        I can sympathize, and agree, with your plaint about so many modes and
        finding someone to talk with. Fortunately, for me. if a new mode
        comes along we will take the opportunity to look at it on one of our
        digital nets, and then whatever happens will happen as far as what we
        do with it. If some of us want to look at it further, we will simply
        set up a sked and do so at a time of our convenience.

        With respect to FNpsk, I only know was is found on the referenced web
        site. I personally am not aware of any dedicated reflectors at this
        point in time, although that is not to say one doesn't exist.

        Finally, with respect to "lab" testing, it is essential for the
        development of software. However, as long as one does not disregard
        new advances, the old axiom about "not fixing something that works"
        is still valid.


        Stewart NNN0STE W1UVE

        --- In Q15X25@yahoogroups.com, "Rick Williams" <mrfarm@m...> wrote:
        > Stewart wrote:
        > >>>>> To encapsulate our thoughts on MT63, based on consistant use
        over two
        > years, there is nothing that has touched it when conditions have
        > deteriorated to the point that other modes have dropped out of
        > It is not unusual to be receiving solid copy on the screen and not
        > see anything on the waterfall or hear anything from the speaker. P-
        > III, let alone any other mode, as good as it is, does not appear to
        > match MT63 down in the trenches.
        > =====
        > I wonder why your experiences are so different from the actual
        tests done
        > with measuring how deep into the noise MFSK16 and other modes are
        able to do
        > compared with MT63?
        > Of all the modes MT63 is about the worst in terms of weak signals!
        > Pactor is really very good and my understanding is that it works
        well below
        > what some have claimed at only -5 db S/N.
        > But I think the largest factor for MARS is that MT63 is able to TX
        > faster data rates due to the huge BW. Many times larger than most
        of the
        > other digital modes. This works OK on a voice channel but not so
        good for
        > spectrum conservation.
        > One thing that MT63 does extremely well is handle multipath and if
        you are
        > often using NVIS, you will encounter this phenomenon to a greater
        > than longer distance TX. Is it possible that this may be another
        reason for
        > the apparent success of MT63?
        > >>>> Incidentally, if you are interested, there is an excellent
        > implementation of an ARQ application of QPSK63 to be found at:
        > http://www.w1fn.org FNpsk, a freeware program, effectively
        > automates the conduct of a digital net to a very high degree.
        > ======
        > This is completely new to me and have not seen this before. Any
        others here
        > finding this to work well?
        > Is there a list or group that discusses this mode?
        > What is happening though is that there are so many modes, and so
        few digital
        > operators of these modes, that you rarely find anyone else to
        connect with.
        > For example, I have tried MT63 on 30 and 40 meters with no luck
        > anyone else. With a more commonly used mode, such as PSK31, it is
        > easier to find someone.
        > 73,
        > Rick, KV9U
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