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Re: [wsjtgroup] Report on 6M ISCAT-A vs. -B comparisons

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  • Bruce Brackin
    Jim, Roger, et.al. If you compute the simple 95% confidence intervals for the proportion of A and B decodes, there s no statistical or practical difference.
    Message 1 of 5 , Oct 8, 2012
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      Jim, Roger, et.al.  If you compute the simple 95% confidence intervals for the proportion of A and B decodes, there's no statistical or practical difference.  Given the small sample size (30 and 37), you'd expect fairly wide error bars.  Probably the luck (or unlucky) of the draw.

      Keep up the good work.

      Bruce N5SIX

      "I still couldn't resist looking at the decode scores (1, 0.5 and 0) for the two modes individually at a reported -20 S/N. ISCAT-A scored 9/30 or 30% and ISCAT-B scored 9.5/37 or 25.7%. I'm still not sure how to interpret this given the differences in reported S/N values, and as Joe commented, these comparisons between modes may not be valid."
       
    • Barry Garratt
      Bruce et al, Actually I wouldn t expect wide errors at all Bruce even with the small sample size. Remember the testing was all being done basically with
      Message 2 of 5 , Oct 8, 2012
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        Bruce et al,

         

        Actually I wouldn’t expect wide errors at all Bruce even with the small sample size. Remember the testing was all being done basically with meteors and the mode isn’t designed for that. Hence both modes performed equally poorly. Conversely FSK441 works very well for MS because that’s what it was designed for. If the tests were run against FSK441 I would expect to see a wide margin between the modes but not between the two Iscat modes.

         

        Interesting tests nonetheless and good documentation Jim.

         

        Barry KS7DX

         

         

        From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Bruce Brackin
        Sent: Monday, October 08, 2012 5:41 PM
        To: Jim and Hannelore Fisher
        Cc: wsjtgroup@yahoogroups.com; Roger Sturtevant
        Subject: Re: [wsjtgroup] Report on 6M ISCAT-A vs. -B comparisons

         

         

        Jim, Roger, et.al.  If you compute the simple 95% confidence intervals for the proportion of A and B decodes, there's no statistical or practical difference.  Given the small sample size (30 and 37), you'd expect fairly wide error bars.  Probably the luck (or unlucky) of the draw.

        Keep up the good work.

        Bruce N5SIX

        "I still couldn't resist looking at the decode scores (1, 0.5 and 0) for the two modes individually at a reported -20 S/N. ISCAT-A scored 9/30 or 30% and ISCAT-B scored 9.5/37 or 25.7%. I'm still not sure how to interpret this given the differences in reported S/N values, and as Joe commented, these comparisons between modes may not be valid."

         

      • Leigh Rainbird
        G day, I downloaded the new version over the weekend and did some testing with ISCAT B and JT65a on the 6m band. I should have spent some more time on it and
        Message 3 of 5 , Oct 8, 2012
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          G'day,
           
          I downloaded the new version over the weekend and did some testing with ISCAT B and JT65a on the 6m band. I should have spent some more time on it and tried ISCAT A. I may do that still.
           
          But just briefly, I found that ISCAT B worked OK for meteors but not so good for direct, constant type signals like tropo.
          The meteors had to be quite long duration to obtain a full decode with no errors, short pings weren't good enough. The tropo signals needed to become quite strong before any real info could be obtained from the message being sent.
          These tests were with stations 770 and 400 km ranges.
           
          On the shorter 400 km paths, I tried for maybe an hour with VK3SMC and got nothing decoded despite being able to hear the signal by ear at times. This is mainly on tropo. We decided to try JT65a in comparison, and from the very first transmissions we had decoded right away and completed in about 5 mins.
           
          So from this test Ive currently concluded that on 6m paths via E or F layer, JT65a wins hands down over ISCAT.
           
          I will find another station and test ISCAT A and see how it goes for us.
           
          Leigh VK2KRR
           
           
          ----- Original Message -----
          Sent: Tuesday, October 09, 2012 12:52 PM
          Subject: RE: [wsjtgroup] Report on 6M ISCAT-A vs. -B comparisons

           

          Bruce et al,

          Actually I wouldn’t expect wide errors at all Bruce even with the small sample size. Remember the testing was all being done basically with meteors and the mode isn’t designed for that. Hence both modes performed equally poorly. Conversely FSK441 works very well for MS because that’s what it was designed for. If the tests were run against FSK441 I would expect to see a wide margin between the modes but not between the two Iscat modes.

          Interesting tests nonetheless and good documentation Jim.

          Barry KS7DX

          From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Bruce Brackin
          Sent: Monday, October 08, 2012 5:41 PM
          To: Jim and Hannelore Fisher
          Cc: wsjtgroup@yahoogroups.com; Roger Sturtevant
          Subject: Re: [wsjtgroup] Report on 6M ISCAT-A vs. -B comparisons

           

          Jim, Roger, et.al.  If you compute the simple 95% confidence intervals for the proportion of A and B decodes, there's no statistical or practical difference.  Given the small sample size (30 and 37), you'd expect fairly wide error bars.  Probably the luck (or unlucky) of the draw.

          Keep up the good work.

          Bruce N5SIX

          "I still couldn't resist looking at the decode scores (1, 0.5 and 0) for the two modes individually at a reported -20 S/N. ISCAT-A scored 9/30 or 30% and ISCAT-B scored 9.5/37 or 25.7%. I'm still not sure how to interpret this given the differences in reported S/N values, and as Joe commented, these comparisons between modes may not be valid."

        • Jim and Hannelore Fisher
          Some additional thoughts on yesterday s report, prompted by several emails and a conversation with VE1SKY: o My personal focus is not on evaluating FSK441
          Message 4 of 5 , Oct 9, 2012
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            Some additional thoughts on yesterday's report, prompted by several emails and a conversation with VE1SKY:
            o    My personal focus is not on evaluating FSK441 vs. ISCAT. I assume that if M/S pings are all that are going on FSK441 will outperform ISCAT for the distances feasible for M/S. (My impression is that more than one propagation mode was weakly active during these tests.) My 6M goal is DXCC (will complete my 10BDXCC since I just wrapped up my 9th band), and all DXCC entities within M/S reach for me are already worked or are easily worked by other modes. Therefore, having already used JT65A for EME and terrestrial DX and ISCAT-B to work EU, I am seeking to get a feel for how -A and -B perform under different circumstances and be ready for further studies and hopefully a bunch of new countries in EU, AF and maybe AS during the next transatlantic Es season.
            o    VE1SKY and I have both been heard via aurora in EU on ISCAT (-B at the time) and I am hopeful -A will be at least as good (perhaps in part due to greater tolerance for Doppler as well as the additional 1dB sensitivity?) and will result in some additional DX possibilities when the moon is down and Es and F2 are quiet. Using some of the near-real-time aurora images on Internet, I expect us to be able to refine our aiming techniques and understanding and use ON4KST 50-70 to alert potential QSO partners in EU when it may be useful to look for us. As a fellow HF contester used to say, you aren't loud if you aren't on.
            o    Others may wish to test FSK441 vs. ISCAT-A and/or B, but I am particularly hopeful that European stations will continue their gradual acceptance of ISCAT as an improvement over JT6M. Perhaps somebody who considers this still an unresolved issue would like to design and conduct a compressed test rapidly alternating JT6M with ISCAT-A and/or -B during transatlantic openings. I take K1JT's word that ISCAT is better than JT6M and am mainly interested in deciding when to use -A or -B or JT65A.
             
            I am hoping some additional members of our 6M digital community will either replicate or hopefully improve our test. For one thing, I am sure some others with deeper technical understanding can make better use of the complete raw data collected including all.txt data columns other than S/N. I still feel that the compressed alternations and various stations' all.txt records including segment-by-segment S/N figures provided me with a better feel than a series of individual QSOs spread over time.
             
            73,
             
            Jim VE1JF
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