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Re: [BPQ32] Re: 9600 baud packet instability

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  • Rick Nicholson
    I agree totally, I ve had the Dr235t in operation for a year and found its performance on 9.6k nominal and unreliable as a backbone, During heavy use the
    Message 1 of 23 , Nov 16, 2012
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      I agree totally, I've had the Dr235t in operation for a year and found its performance on 9.6k nominal and unreliable as a backbone, 
      During heavy use the dr235t will distort the packets to the points they cannot be decoded even at short distances. 



      I've found that the Tait  8105 a much better choice for a backbone transceiver. 
      Ive been using the Tait's  for repeater linking and remote voter sites for several years, after months of testing numerous commercial brands the Tait out performs them all and we will be changing out the Dr235t for the Tait after the first of the year. 
       
      I'm hoping others in Indiana will realize the issues with the Dr235t and standardize with the Tait for the 220 backbone.

      Rick/ n9umj



      Sent from my iPhone

      On Nov 15, 2012, at 8:17 AM, "Jeff - WA4ZKO" <wa4zko@...> wrote:

       

      Alinco DR-235's are very marginal radios for 9.6k. The ARRL Lab BER testing for them reveals the problem.

      You can probably pull your PACLEN back to 64 or 32 and see a small improvement in terms of retries at a cost of reduced throughput. You might do a bit better with a TNC that uses a true G3RUH modem, but I suspect you are fighting an uphill battle with a marginal radio for 9.6k (regardless of how it's advertised).

      The DR-235 (and DR-435) rigs are good for 1200 baud, but horrid for 9600 baud. If this is a backbone link (no users) you will do far better just running 1200 baud and opening up the parms (paclen, maxframe, ect).

      As others have said deviation is important, but unless you are using older or modified radios with "wider" filters you will probably find the 9.6k sweet spot on newer gear is around 2.8KHz peak deviation. Make sure your meter can show/measure peak deviation.

      73
      Jeff
      WA4ZKO
      "Packet Radio never died, it just evolved."
      http://twitter.com/wa4zko

      --- In BPQ32@yahoogroups.com, "k1jtc" <jeffrey.t.clark@...> wrote:
      >
      > Rather than reply to all I will post all replies here. I am running alinco 235. I have 2 radios sitting in the same room. From what I understand the KPC 9612 only supports 9600 baud on the com port so that is the highest speed to go to the computer. Am I wrong? S meter readings are full scale in the room as well as when I try across the city. The radios are identical except the one that is not hooked to the bbs has the internal tnc option.
      >
      > --- In BPQ32@yahoogroups.com, "N9ACQ" <n9acq@> wrote:
      > >
      > > Jeff
      > >
      > > The biggest problem with 9600 is deviation. Both ends should
      > > be around 3 Khz. 9600 also need to bypass all audio amplifiers and filters
      > > on both transmit and receive. A deviation meter really is needed to set the
      > > proper audio level to the radio. The other thing is what is the S meter
      > > reading on receive?
      > >
      > > 73 Bill
      > >
      > > N9ACQ
      > >
      >

    • Bill Vodall
      ... Is that with the built in 9k6 TNC or a good external TNC like the PK96? Thanks, Bill - WA7NWP
      Message 2 of 23 , Nov 16, 2012
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        > I agree totally, I've had the Dr235t in operation for a year and found its
        > performance on 9.6k nominal and unreliable as a backbone,
        > During heavy use the dr235t will distort the packets to the points they
        > cannot be decoded even at short distances.

        Is that with the built in 9k6 TNC or a "good" external TNC like the PK96?

        Thanks,
        Bill - WA7NWP
      • Jeff - WA4ZKO
        My experience is the modem in the PK-96 and the 9612 TNCs perform the same. Neither are true G3RUH modems, but both work well with a good 9.6k radio. Best TNC
        Message 3 of 23 , Nov 16, 2012
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          My experience is the modem in the PK-96 and the 9612 TNCs perform the same. Neither are true G3RUH modems, but both work well with a good 9.6k radio.

          Best TNC in the world can't make up for BER specs like these, especially when you start off listening to a TX BER that bad.
          (DR-235 BER data per ARRL Lab results)

          Receiver:
          BER at 12-dB SINAD, 3.8×10–3
          BER at 16 dB SINAD, 1.4×10–4
          BER at –50 dBm, 2.4×10–5
          transmitter:
          BER at 12-dB SINAD + 30 dB, 3.4×10–4

          Pretty decent TXDelay, but the RX/TX BER is the problem.

          Good to know there's a usable commercial "off-the-shelf 220 radio out there with the Tait rigs.

          Be nice if the ARRL would get back to publishing BER Test data on the newer rigs. Then maybe crack down on manufacturers advertising rigs as "9600 ready" if they don't meet a minimal BER spec.


          73
          Jeff
          WA4ZKO
          "Packet Radio never died, it just evolved."
          http://twitter.com/wa4zko

          --- In BPQ32@yahoogroups.com, Bill Vodall <wa7nwp@...> wrote:
          >
          > > I agree totally, I've had the Dr235t in operation for a year and found its
          > > performance on 9.6k nominal and unreliable as a backbone,
          > > During heavy use the dr235t will distort the packets to the points they
          > > cannot be decoded even at short distances.
          >
          > Is that with the built in 9k6 TNC or a "good" external TNC like the PK96?
          >
          > Thanks,
          > Bill - WA7NWP
          >
        • Bill Vodall
          ... What numbers would a good radio have? 1x10-6? Thanks, Bill
          Message 4 of 23 , Nov 16, 2012
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            > (DR-235 BER data per ARRL Lab results)
            >
            > Receiver:
            > BER at 12-dB SINAD, 3.8×10–3
            > BER at 16 dB SINAD, 1.4×10–4
            > BER at –50 dBm, 2.4×10–5
            > transmitter:
            > BER at 12-dB SINAD + 30 dB, 3.4×10–4

            What numbers would a good radio have? 1x10-6?

            Thanks,
            Bill
          • PE1RDW
            ... probably 0 but the only radio I ever found that has that is a converted analog cell phone like nokia morbia -- 73 Andre PE1RDW
            Message 5 of 23 , Nov 16, 2012
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              On Fri, 16 Nov 2012 21:15:32 +0100, Bill Vodall <wa7nwp@...> wrote:

              >> (DR-235 BER data per ARRL Lab results)
              >>
              >> Receiver:
              >> BER at 12-dB SINAD, 3.8×10–3
              >> BER at 16 dB SINAD, 1.4×10–4
              >> BER at –50 dBm, 2.4×10–5
              >> transmitter:
              >> BER at 12-dB SINAD + 30 dB, 3.4×10–4
              >
              > What numbers would a good radio have? 1x10-6?
              >
              > Thanks,
              > Bill
              >
              probably 0 but the only radio I ever found that has that is a converted
              analog cell phone like nokia morbia

              --
              73 Andre PE1RDW
            • Jeff - WA4ZKO
              1.0x10-5 (or better) is good benchmark to look for on the RX BER at –50 dBm test and the TX BER at 12-dB SINAD+30 dB test. If a radio can t perform well at
              Message 6 of 23 , Nov 16, 2012
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                1.0x10-5 (or better) is good benchmark to look for on the RX BER at –50 dBm test and the TX "BER at 12-dB SINAD+30 dB" test. If a radio can't perform well at those levels then good luck with it on the 9.6k airwaves.

                http://wx4j.com/Radio-TNC9600bInfoC.htm

                A really good article by KE3Z in the May 1995 QST goes into BER testing details and what makes a good 9600 baud radio (or not). Unfortunately I don't think it's openly available on the internet.
                I might check to see if the ARRL would allow me to PDF it and post it publicly if there is enough interest.


                73
                Jeff
                WA4ZKO
                "Packet Radio never died, it just evolved."
                http://twitter.com/wa4zko

                --- In BPQ32@yahoogroups.com, Bill Vodall <wa7nwp@...> wrote:
                >
                > > (DR-235 BER data per ARRL Lab results)
                > >
                > > Receiver:
                > > BER at 12-dB SINAD, 3.8×10–3
                > > BER at 16 dB SINAD, 1.4×10–4
                > > BER at –50 dBm, 2.4×10–5
                > > transmitter:
                > > BER at 12-dB SINAD + 30 dB, 3.4×10–4
                >
                > What numbers would a good radio have? 1x10-6?
                >
                > Thanks,
                > Bill
                >
              • Bill Vodall
                Thank you Jeff.. That s good info to keep on had. Bill
                Message 7 of 23 , Nov 16, 2012
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                  Thank you Jeff.. That's good info to keep on had.

                  Bill

                  > 1.0x10-5 (or better) is good benchmark to look for on the RX BER at –50
                  > dBm test and the TX "BER at 12-dB SINAD+30 dB" test. If a radio can't
                  > perform well at those levels then good luck with it on the 9.6k airwaves.
                  >
                  > http://wx4j.com/Radio-TNC9600bInfoC.htm
                • Rick Nicholson
                  That was with a Kantronics KPC-9612 and on a Timewave DSP-232USB. Rick/n9umj Sent from my iPhone
                  Message 8 of 23 , Nov 16, 2012
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                    That was with a Kantronics KPC-9612 and on a Timewave DSP-232USB. 

                    Rick/n9umj


                    Sent from my iPhone

                    On Nov 16, 2012, at 11:31 AM, Bill Vodall <wa7nwp@...> wrote:

                     

                    > I agree totally, I've had the Dr235t in operation for a year and found its
                    > performance on 9.6k nominal and unreliable as a backbone,
                    > During heavy use the dr235t will distort the packets to the points they
                    > cannot be decoded even at short distances.

                    Is that with the built in 9k6 TNC or a "good" external TNC like the PK96?

                    Thanks,
                    Bill - WA7NWP

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