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[dxatlas] Re: CW Skimmer 1.1 doesn't allow for transceivers with more than 3 KHz

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  • bill_w4zv
    ... Since the bands are so poor I downloaded the pileup file (FJ/OH2AM) and my system seemed to handle it fairly well. 67 calls identified between 7006.4 and
    Message 1 of 19 , Apr 23, 2008
      --- In dxatlas_group@yahoogroups.com, "bill_w4zv" <w0zv@...> wrote:

      > I'm only seeing 3 kHz on the display but I think it may be capturing
      > signals further away...the bands are so poor I'm having trouble
      > finding enough signals strong enough to test! I'm sampling at 48 kHz
      > since I'm running an underpowered CPU (1.1GHz P3 + 1GB RAM > Delta 44
      > > LP-PAN > K3).

      Since the bands are so poor I downloaded the pileup file (FJ/OH2AM)
      and my system seemed to handle it fairly well. 67 calls identified
      between 7006.4 and 7018.9 with about 71% CPU utilization (i.e. not
      maxing out). But for some reason my Skimmer display still only shows
      about 3 kHz at a time...maybe I just haven't yet discovered how to
      enable the wide display.

      I then tried the CQWW file below and got the following results, with
      CPU utilization hitting 100% at times in all cases:

      http://cid-e39b59612b664f63.skydrive.live.com/self.aspx/Public/CQWWCW_2005_1_of_42.wav

      33 calls, 7009.0>7020.10, everything running on computer.
      33 calls, same QRG range, Internet connection and browser off.
      40 calls, 7007.0>7021.9, AVG anti-virus off.
      58 calls, 7002.0>7024.6, Skimmer display minimized.

      I could probably do a little better by shutting down more background
      processes but I'm curious what someone with a 2-3 GHz CPU gets when
      running the same CQWW file above?

      A couple of things strike me so far:

      1. Is it possible to suppress decoders for zero point station QRGs
      once they are identified? 23 of the 58 in the last run were USA.
      This would make for a less cluttered display and probably free up some
      resources. I suppose USA calls would be eliminated from a band map in
      a contest program anyway but am just curious.

      2. I'm not sure how well Skimmer will work with very weak signals.
      It seems to pick up signals with good S/N very well but I'm wondering
      how it might work for weak DX signals on a band like 160? Has anyone
      had much experience with weak signals? It could be I'm still not set
      up correctly but it seems like you need a real S5 signal or better for
      it to decode calls quickly. I can hear many Q5 signals on the K3 that
      don't even register solidly on Skimmer's waterfall.

      I definitely plan to upgrade my computer eventually but am just
      playing with what I have for now and am curious about others' experiences.

      73, Bill
    • Pete Smith
      ... Your wish is my command, sir ;^) With a 2.2 GHz Celeron, 768 MB DDR RAM (a VERY basic Dell 2400, four years old, With XP home SP2) I got the following
      Message 2 of 19 , Apr 24, 2008
        At 05:19 PM 4/23/2008, bill_w4zv wrote:
        >I then tried the CQWW file below and got the following results, with
        >CPU utilization hitting 100% at times in all cases:
        >
        >http://cid-e39b59612b664f63.skydrive.live.com/self.aspx/Public/CQWWCW_2005_1_of_42.wav
        >
        >33 calls, 7009.0>7020.10, everything running on computer.
        >33 calls, same QRG range, Internet connection and browser off.
        >40 calls, 7007.0>7021.9, AVG anti-virus off.
        >58 calls, 7002.0>7024.6, Skimmer display minimized.
        >
        >I could probably do a little better by shutting down more background
        >processes but I'm curious what someone with a 2-3 GHz CPU gets when
        >running the same CQWW file above?


        Your wish is my command, sir ;^)

        With a 2.2 GHz Celeron, 768 MB DDR RAM (a VERY basic Dell 2400, four years
        old, With XP home SP2) I got the following results off the same file.

        Note that when playing back recordings the sound card is not involved;
        Skimmer is processing the I/Q file directly, so settings like playback
        sampling rate have no effect:

        Decoders Other variables Calls Decoded CPU peak
        utilization

        Adaptive Not minimized 156 96%
        250 "" 131 75%
        300 "" 152 81%
        350 "" 154 86%
        400 "" 153 100%
        Adaptive Telnet server off 154 100%
        Adaptive Skimmer minimized 154 ?

        Interesting, no? I would have to other programs minimized or in the
        background do not affect decoding performance; one of the critical
        questions I hope to answer in coming months is whether the reverse is true,
        since we're talking about using Skimmer to feed spots to a contest logging
        program, which has to be able to respond quickly, send CW, etc. My
        personal tests with N1MM logger, using a Winkey for CW, have been very
        encouraging; I suspect that MM simply takes precedence when it needs to,
        and that the Winkey avoids any issues with making good CW.

        73, Pete N4ZR
      • rt_tclay
        Is the reason you only see 3 KHz because you haven t resized the Skimmer window? Just drag the bottom edge to make it bigger. Tor N4OGW
        Message 3 of 19 , Apr 25, 2008
          Is the reason you only see 3 KHz because you haven't resized the
          Skimmer window? Just drag the bottom edge to make it bigger.

          Tor
          N4OGW
        • rt_tclay
          ... with Similar results here on the CQWW file. Running with graphics window shrunk down. XP Pro SP2. 1) old 1 GHz AMD Athlon. 1.25 GB RAM maxed out 100% CPU,
          Message 4 of 19 , Apr 25, 2008
            --- In dxatlas_group@yahoogroups.com, Pete Smith <n4zr@...> wrote:
            >
            > At 05:19 PM 4/23/2008, bill_w4zv wrote:
            > >I then tried the CQWW file below and got the following results,
            with


            Similar results here on the CQWW file. Running with graphics window
            shrunk down. XP Pro SP2.

            1) old 1 GHz AMD Athlon. 1.25 GB RAM

            maxed out 100% CPU, decoded only 69 calls

            2) 1.8 GHz AMD Sempron ("3100+" model I think), 1 GB RAM

            max CPU 70-80%, 155 calls


            Given that CPU never hit 100% on the second system, I would say that
            throwing more CPU at it won't give more calls decoded. Of course if
            it ran for longer, the number of decoders might increase enough to
            hit 100%. I think to test performance on faster CPU's you need a
            longer sample.

            Tor
            N4OGW
          • bill_w4zv
            Thanks Pete and Tor! Yes Tor, I simply had not discovered how to increase the window size on the display. How do you feel about Skimmer s ability to decode
            Message 5 of 19 , Apr 26, 2008
              Thanks Pete and Tor! Yes Tor, I simply had not discovered how to
              increase the window size on the display.

              How do you feel about Skimmer's ability to decode weaker signals in
              QSB and QRN? I'm somewhat unimpressed so far but it could be I'm not
              doing something right. Does the DSP filter width affect all decoders
              or just the one displayed with the green bar? Based on what I've seen
              so far, Skimmer would be great for identifying strong stations CQ-ing
              or in a pileup but it doesn't work very well for weaker signals, which
              would likely be the very ones you want to know about. But this could
              be due to my not setting Skimmer up correctly or due to my weak
              computer. BTW, I noticed 3GHz P4's on eBay go for <$150 so I may pick
              up one of these to solve the latter issue.

              73, Bill W4ZV


              --- In dxatlas_group@yahoogroups.com, Pete Smith <n4zr@...> wrote:
              >
              > At 05:19 PM 4/23/2008, bill_w4zv wrote:
              > >I then tried the CQWW file below and got the following results, with
              > >CPU utilization hitting 100% at times in all cases:
              > >
              >
              >http://cid-e39b59612b664f63.skydrive.live.com/self.aspx/Public/CQWWCW_2005_1_of_42.wav
              > >
              > >33 calls, 7009.0>7020.10, everything running on computer.
              > >33 calls, same QRG range, Internet connection and browser off.
              > >40 calls, 7007.0>7021.9, AVG anti-virus off.
              > >58 calls, 7002.0>7024.6, Skimmer display minimized.
              > >
              > >I could probably do a little better by shutting down more background
              > >processes but I'm curious what someone with a 2-3 GHz CPU gets when
              > >running the same CQWW file above?
              >
              >
              > Your wish is my command, sir ;^)
              >
              > With a 2.2 GHz Celeron, 768 MB DDR RAM (a VERY basic Dell 2400, four
              years
              > old, With XP home SP2) I got the following results off the same file.
              >
              > Note that when playing back recordings the sound card is not involved;
              > Skimmer is processing the I/Q file directly, so settings like playback
              > sampling rate have no effect:
              >
              > Decoders Other variables Calls Decoded CPU
              peak
              > utilization
              >
              > Adaptive Not minimized 156 96%
              > 250 "" 131 75%
              > 300 "" 152 81%
              > 350 "" 154 86%
              > 400 "" 153 100%
              > Adaptive Telnet server off 154 100%
              > Adaptive Skimmer minimized 154 ?
              >
              > Interesting, no? I would have to other programs minimized or in the
              > background do not affect decoding performance; one of the critical
              > questions I hope to answer in coming months is whether the reverse
              is true,
              > since we're talking about using Skimmer to feed spots to a contest
              logging
              > program, which has to be able to respond quickly, send CW, etc. My
              > personal tests with N1MM logger, using a Winkey for CW, have been very
              > encouraging; I suspect that MM simply takes precedence when it needs
              to,
              > and that the Winkey avoids any issues with making good CW.
              >
              > 73, Pete N4ZR
              >
            • rt_tclay
              ... not ... decoders ... seen I don t know for sure, but I think the program just uses the green bar setting for the audio output filter width. I can copy
              Message 6 of 19 , Apr 26, 2008
                --- In dxatlas_group@yahoogroups.com, "bill_w4zv" <w0zv@...> wrote:
                >
                > Thanks Pete and Tor! Yes Tor, I simply had not discovered how to
                > increase the window size on the display.
                >
                > How do you feel about Skimmer's ability to decode weaker signals in
                > QSB and QRN? I'm somewhat unimpressed so far but it could be I'm
                not
                > doing something right. Does the DSP filter width affect all
                decoders
                > or just the one displayed with the green bar? Based on what I've
                seen

                I don't know for sure, but I think the program just uses the green
                bar setting for the audio output filter width.

                I can copy better than Skimmer on weak signals. If you watch it
                trying to copy a weak signal, it usually gets a few letters correct
                each time, but has a hard time putting together the full correct
                callsign. That's where the brain obviously has an advantage, when you
                are copying you can say definitely if you copied a particular letter
                and mark that mentally as "good copy".

                If on your computer Skimmer is reaching 100% cpu, then yes, it is
                having to reduce the number of decoders. I don't know the algorithm
                used to do that, but yes, it might do that based signal strength. Try
                reducing the bandwidth. My old 1GHz Athlon can't keep up with 96 KHz,
                but is ok at 48 KHz if the band isn't too busy.

                Tor
                N4OGW
              • Pete Smith
                ... Hi Bill - I think you may need to do some experimenting to maximize Skimmer s weak-signal performance. I may have mentioned this already, but a great deal
                Message 7 of 19 , Apr 26, 2008
                  At 09:20 AM 4/26/2008, bill_w4zv wrote:
                  >How do you feel about Skimmer's ability to decode weaker signals in
                  >QSB and QRN? I'm somewhat unimpressed so far but it could be I'm not
                  >doing something right. Does the DSP filter width affect all decoders
                  >or just the one displayed with the green bar? Based on what I've seen
                  >so far, Skimmer would be great for identifying strong stations CQ-ing
                  >or in a pileup but it doesn't work very well for weaker signals, which
                  >would likely be the very ones you want to know about. But this could
                  >be due to my not setting Skimmer up correctly or due to my weak
                  >computer.

                  Hi Bill - I think you may need to do some experimenting to maximize
                  Skimmer's weak-signal performance. I may have mentioned this already, but
                  a great deal depends on the dynamic range of the line input of your
                  soundcard. Whichever card you use, you need to make sure that the input
                  gain is set just short of clipping, in order to get the closest possible
                  approximation of the sensitivity of the receiver alone. and of course, you
                  are comparing it with one of the best receivers ever made - no fair hi.

                  73, Pete N4ZR
                • Pete Smith
                  ... One of the most effective tricks is to uncheck the Adaptive decoder box, and set a specified maximum number of decoders. Hitting 100% isn t so
                  Message 8 of 19 , Apr 26, 2008
                    At 02:01 PM 4/26/2008, rt_tclay wrote:
                    >If on your computer Skimmer is reaching 100% cpu, then yes, it is
                    >having to reduce the number of decoders. I don't know the algorithm
                    >used to do that, but yes, it might do that based signal strength. Try
                    >reducing the bandwidth. My old 1GHz Athlon can't keep up with 96 KHz,
                    >but is ok at 48 KHz if the band isn't too busy.


                    One of the most effective tricks is to uncheck the "Adaptive" decoder box,
                    and set a specified maximum number of decoders. Hitting 100% isn't so
                    important, in my view, as eliminating most of the junk you get from
                    Skimmer's trying to decode on RTTY signals. If you set a maximum number of
                    decoders, Alex says that Skimmer accommodates that by narrowing the band of
                    frequencies that it attempts to decode, centered around the center
                    frequency of the waterfall display. Experimentally, I discovered that 150
                    decoders seemed pretty much to eliminate anything above about 14060 on a
                    normally busy weekend band, when I set the waterfall on 14030. Today,
                    running 300 decoders, I'm getting a lot of "AA4EE" type "callsigns" in the
                    14070 and above range. During a major contest, you might have to set it to
                    a higher number to get the same approximate frequency coverage.

                    73, Pete N4ZR
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