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New guy questions

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  • Charles Brabham
    Howdy! My name is Charles, I live in San Benito, TX, in the southern tip of the state. Palm trees, South Padre Island, Mexico, spring break, and so on. It s
    Message 1 of 3 , May 10, 2003
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      Howdy!

      My name is Charles, I live in San Benito, TX, in the southern tip of
      the state. Palm trees, South Padre Island, Mexico, spring break, and
      so on. It's kind of hot and sticky down here, right now.

      I've recently set up the MixW Q15x25 package as recommended, and
      tuned around for sigs. So far I haven't found anything, probably
      looking at the wrong time or place.

      I'm also interested in the earlier version, Newqpsk, that is included
      in Thomas Sailer's "soundmodem" driver for Flex32. I've noticed that
      Newqpsk is not as advanced as Q15x25, but the easy gateway between
      Packet and Newqpsk that Flex32 makes possible makes it very
      attractive.

      Is anyone here familiar with the latest release of "soundmodem" and
      Flex32? I'm wondering about that version of Newqpsk's viability on
      HF, since it is an earlier version.

      Also: I've noticed that the MixW version of Q15x25 is limited to a
      PACLEN of 256. - But the Flex32 Newqpsk has no provision in its setup
      screens for PACLEN at all. I have a multicast application in mind
      that requires a PACLEN of 1000... Does anyone here know how the
      Flex32 version of Newqpsk handles PACLEN?

      Sorry to barrage you guys with all of these questions, but I am
      interested in this mode, and have to learn somehow.

      One thing that I am wondering about is how Q15x25 behaves for file
      transfers, etc... I'm thinking that if it drops characters or gets
      garbage characters, then the only way to use it as a file server
      would be the multicast approach, as it would give the additional
      layer of error correction needed for reliability.

      I still haven't tested-driven the multicast software with Flex32, so
      my interest in that may be premature. In theory, it should work just
      fine, except for the PACLEN issue.

      If worse comes to worse, the author of the multicast software could
      tweak the PACLEN down to 265 for this application, but I'd rather not
      ask for that kind of favor unless it is absolutely necessary.

      Besides that, reducing the PACLEN of the multicasts will reduce the
      system's efficiency considerably by increasing the packet overhead.
      One great thing about multicast with the 1k PACLEN is the reduced
      overhead. It's almost all data, just like it should be for that
      purpose. (File-server)

      I've done some testing on VHF, and by increasing the TXDELAY quite a
      bit, I even managed to connect to a buddy over the local voice
      repeater. ( I had permission ) For 1200bd packet at least, the
      Packet/Newqpsk gateway seems to work perfectly. Users can connect to
      the packet node, then digi through my Flex32 setup and come out on
      HF, in Newqpsk mode... Now to see how the HF end of it behaves!

      Any help on this stuff would be greatly appreciated. I'd also like to
      QSO, get a chance to play with the MixW version a little!

      Charles Brabham N5PVL
      n5pvl@...
      http://www.uspacket.net
    • Tomi Manninen
      ... They are both exactly the same. They are actually built from exactly the same source code. So the features and performance are the same also. ... The
      Message 2 of 3 , May 11, 2003
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        On Sun, 11 May 2003, Charles Brabham wrote:

        > I'm also interested in the earlier version, Newqpsk, that is included
        > in Thomas Sailer's "soundmodem" driver for Flex32. I've noticed that
        > Newqpsk is not as advanced as Q15x25, but the easy gateway between
        > Packet and Newqpsk that Flex32 makes possible makes it very
        > attractive.

        They are both exactly the same. They are actually built from exactly the
        same source code. So the features and performance are the same also.

        > Also: I've noticed that the MixW version of Q15x25 is limited to a
        > PACLEN of 256. - But the Flex32 Newqpsk has no provision in its setup
        > screens for PACLEN at all. I have a multicast application in mind
        > that requires a PACLEN of 1000... Does anyone here know how the
        > Flex32 version of Newqpsk handles PACLEN?

        The newqpsk/q15x25 modem should not limit the PACLEN in any way. The
        possible limitations come from the AX.25 protocol stack used. In MixW, the
        internal protocol stack seems to limit it to 256. For FlexNet32 I don't
        know if there is a limitation.

        Anyway the FlexNet32 protocol stack gives the user very limited control on
        the channel parameters (like paclen, frack, txdelay etc...). It has
        complex algorithms to calculate those parameters automatically based on
        the channel usage pattern. I'm not sure if those algorithms work well on
        HF or with q15x25 altogether...

        Unless there is a way to tweak these parameters your self (I'm not a
        FlexNet32 guru so I cannot say for sure) this may be a problem for those
        wishing to use FlexNet32 for q15x25 on HF.

        > One thing that I am wondering about is how Q15x25 behaves for file
        > transfers, etc... I'm thinking that if it drops characters or gets
        > garbage characters,

        It's an AX.25 mode. AX.25 (in connected mode) will guarantee 100% error
        free connection (or nothing if the channel is too bad).

        --
        Tomi Manninen Internet: oh2bns@...
        OH2BNS AX.25: oh2bns@...
        KP20ME04 Amprnet: oh2bns@...
      • Charles Brabham
        Thanks, Tomi! I experimented with FlexNet and 300 baud HF packet five years or so ago. As you would expect, FlexNet was too aggressive, not backing off on
        Message 3 of 3 , May 11, 2003
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          Thanks, Tomi!

          I experimented with FlexNet and 300 baud HF packet five years or so
          ago. As you would expect, FlexNet was too aggressive, not backing off
          on MAXFRAME and PACLEN enough for reliable HF packet.

          The FlexNet system would be great for 300 baud packet, but I think it
          would involve rewriting the FlexNet kernal. I'm not sure you could do
          it with just a driver.

          I uploaded a jpeg of a VHF multicast network here, in the PICTURES
          section.... I'd like to try something like that, but on a larger, HF
          scale.

          It seems to me that multicast and Newqpsk were made for each other,
          addressing each other's drawbacks quite well. I'll see what I can do
          with it, and keep the group posted.

          The multicast software I have expects a KISS TNC, which means I'll
          have to use FlexNet's KISS driver in order for it to talk to FlexNet,
          which means that most of FlexNet's control over the link will be
          eliminated. It is my hope that this will allow me to digi the
          multicasts through Flex32 to Newqpsk without too much interference
          from the Flex32 kernal.

          The multicast software will have to be modified to include a digi
          field in the multicast packet header. If Flex32 has a 256 PACLEN
          limit, the multicast software will have to be modified for the
          smaller PACLEN and lose some efficiency. I'll avoid that if at all
          possible.

          That's the theory I'm working on, anyway. It may be that I am overly
          optimistic, but I suppose that is better than the alternative!

          There is an article about VHF multicast in the "Library" section at
          the web address below, and a tutorial on the RadioMirror multicast
          software in the "Tutorials" section.

          There's a new tutorial on Flex32 with the soundmodem in there too.

          Thanks again!

          Charles, N5PVL
          n5pvl@...
          http://www.uspacket.net
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