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Re: 9600 baud packet instability

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  • 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 1 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 2 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 3 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 4 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 5 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 6 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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