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beginner questions

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  • Dan K9ZF
    Hello, Now that I have my feet wet, I m curious about a few things. What sort of filter selections do you use? What about noise limiting? I typically run my
    Message 1 of 4 , Oct 9, 2004
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      Hello,

      Now that I have my feet wet, I'm curious about a few things. What sort of
      filter selections do you use? What about noise limiting? I typically run
      my NB on 6 as I have a lot of QRN. I'm guessing DSP noise reduction would
      be bad as it may distort the tones? What about AGC, fast, slow, or off?

      Also, what about ALC? I run an Icom 746. On SSB I usually adjust the ALC
      meter to "fill the box," but on PSK I set it for NO indication. I've been
      setting the ALC meter for no indication for WSJT modes as well, but wonder
      how the experts do it? This also reduces my tx power out about 20% which I
      figure is a good thing considering the duty cycle...

      Also, I get a lot of "false" decodes of RRR, R26, and 73. Is there any
      tricks to telling real decodes from false ones? I usually listen for the
      pings, but sometimes I don't hear the ping and still get good copy.

      BTW, I'm having a ton of fun learning the modes:-) I'm giving serious
      thought to doing a WSJT focused contest in January. I may work moderately
      fewer QSO's, but the extra mults should make it worthwhile;-)

      73
      Dan
      K9ZF /R no budget Rover ***QRP-l #1269
      Check out the Rover Resource Page at: http://www.qsl.net/n9rla
      List Administrator for: InHam+grid-loc+ham-books
    • Andrew T. Flowers, K0SM
      ... Dan, You need to have the filters wide enough to pass the entire set of tones used in the mode. FSK441 uses tones from 880-2200Hz, and you ll want a
      Message 2 of 4 , Oct 9, 2004
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        Dan K9ZF wrote:

        >Hello,
        >
        >Now that I have my feet wet, I'm curious about a few things. What sort of
        >filter selections do you use?
        >
        Dan,
        You need to have the filters wide enough to pass the entire set of tones
        used in the mode. FSK441 uses tones from 880-2200Hz, and you'll want a
        little headroom on either side. The normal SSB filter on your radio
        (2.4 - 3 KHz typ.) is just fine. Limiting the bandpass really doesn't
        help you any--in theory you should be able to run with the 10KHz filter
        inline and the program will do just fine....in theory :-)

        >What about noise limiting? I typically run
        >my NB on 6 as I have a lot of QRN. I'm guessing DSP noise reduction would
        >be bad as it may distort the tones? What about AGC, fast, slow, or off?
        >
        Depends on the radio. I haven't had any problem with the NB to
        eliminate pulse noise, but others may have other experiences. I've
        heard that some NB's like to eat short, loud pings since they look like
        pulse noise. The DSP noise reduction is likely to cause you problems,
        put you can experiment. AGC should be off--FSK441 detects pings by
        looking at the amplitude of the audio. Having the AGC on defeats that!
        If you can't turn it off set it to fast.

        >Also, what about ALC? I run an Icom 746. On SSB I usually adjust the ALC
        >meter to "fill the box," but on PSK I set it for NO indication.
        >
        The most important thing is that the individual tones are sent at the
        same power output. FSK441 does not require linearity, so "filling the
        box" or not shouldn't matter as long as you get the same output with
        each tone. I would use the least audio necessary without having the
        soundcard audio at either of its extremes. FWIW, PSK31 is a different
        beast--it requires linearity in the system for the phase reversals.
        I've often cranked up the audio drive to let the ALC automatically
        "equalize" the tones on FSK441, though the equalizer in the progam
        probably makes that obsolete.

        >Also, I get a lot of "false" decodes of RRR, R26, and 73. Is there any
        >tricks to telling real decodes from false ones? I usually listen for the
        >pings, but sometimes I don't hear the ping and still get good copy.
        >
        You should be able to hear it and see it on the screen, especially if
        you click the area of the ping to get the zoomed-in view. I usually
        just copy those by ear anyway in the contest situation to speed things
        up :-) After a while you'll hear the difference among them. If I don't
        hear it or see it I don't count it, but if you listen closely you'll
        find this doesn't happen too often.

        >
        >BTW, I'm having a ton of fun learning the modes:-) I'm giving serious
        >thought to doing a WSJT focused contest in January. I may work moderately
        >fewer QSO's, but the extra mults should make it worthwhile;-)
        >
        I've used a couple of the multi-multis here in the Northeast. It's a
        great way to avoid sleeping. Just about everything you work is a new
        multiplier. I think the last time I ran at W2FU we worked 27 stations,
        25 of which were unique multipliers and that added up to just under 10%
        of the score. Of course, one can run multiple bands at the same time,
        but I worked many stations on both 6 and 2, and even two stations on
        222. All of the big M/Ms are running it now between about midnight at
        6am. K1JT had a sidebar in QST about WSJT and contesting a little while
        back.

        Hope that helps some! Have fun with the different modes and I look
        forward to working you in January!
        Andy K0SM/2
      • w5uwb2@aol.com
        Dan: If you right click on the ping it will ignore steady tones. I have seen strong bursts, which I know is multitone and it will decode R26, R27 sometimes.
        Message 3 of 4 , Oct 9, 2004
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          Dan:
           
          If you right click on the ping it will ignore steady tones. I have seen strong bursts, which I know is multitone and it will decode R26, R27 sometimes. The right click will ignore the carrier or whatever it sees in the multitone and give you a decent decode.
           
          I run with AGC off, NB on if required. I do NOT use DSP.
           
          73 es good luck !!
           
          John W5UWB
        • wa3ltb@juno.com
          Hi Dan, I have a 746 on this end also......I run Compression on and slight indication of ALC maybe 1 or 2 bars.....AGC in Fast mode.........NB on in qrn
          Message 4 of 4 , Oct 9, 2004
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            Hi Dan,

            I have a 746 on this end also......I run Compression on and slight
            indication of ALC maybe 1 or 2 bars.....AGC in Fast mode.........NB on in
            qrn conditions, I find that the noise blanker seems to reduce the receive
            level of pings by 1 or 2 db but not to the point that they can't be
            decoded, turn it off when possible though. I don't have much trouble
            with false decodes..I set W>width to 20 andTol> to 400 to start then
            Tol>100 after I find the freq of the signal and tune RIT to correct to
            under 100 hertz. The closer you have the receive signal the better
            overall...I actually listen to the received signals and manually decode
            anything I think might be a ping when possible too. That's about it ....

            Good luck
            Terry
            WA3LTB
            EN92ta
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