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CMSK - Last Nights Activity

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  • Phil Williams
    The software we are using is developed by ZL2AFP and uses a modulation technique called CMSK. The software can be downloaded here:
    Message 1 of 3 , Aug 10, 2010
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      The software we are using is developed by ZL2AFP and uses a modulation technique called CMSK.

      The software can be downloaded here:


      We were operating on 10137.00 KHz last night.  We used the default setting of CMSK63. Tim, N4UM, and myself started to exchange signal.  I was able to copy Tim 100%, but Tim had no luck copying me.

      Tuning is critical with this mode, so we spent a lot of time getting used to how to fine tune the reception of the CMSK signal.  Tim was only able to copy a few characters of my signal.  At this point, I was suspect that the issue maybe related to how my rig was set up.

      K4UI came up on frequency in CMSK.  We were able to copy each other with little problem.  

      For the remainder of the evening.  Don, KB9UMT, worked on trying to decode each other.  I was able to decode Don 100%, but he was unable to decode me.  Reduced my power down to 10 watts and kept an eye on the ALC - thinking that maybe I was just driving the rig too hard, but that did not resolve the issue.

      According to ZL2AFP,  CMSK was design for 160 meters and lower. At these frequencies, the Doppler shift is much less pronounced.  

       I still suspect my rig, but I am baffled as to why K4UI and I were able to exchange traffic w/ little or not issues at all. 

       Is this just a result of conditions on 30 meters and it is possible that Doppler for certain path was more prominent? 

      --
      Philw de KA1GMN
    • Lehman, Rex
      Loaded the CMSK last night and was trying it out on 10.139. Will be on 10.137 tonight trying CMSK 63. Rex WB8TDG Rex Lehman Quality Assurance Measurement
      Message 2 of 3 , Aug 10, 2010
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        Loaded the CMSK last night and was trying it out on 10.139.

        Will be on 10.137 tonight trying CMSK 63.

         

        Rex WB8TDG

         

        Rex Lehman

        Quality Assurance

        Measurement Specialties, Inc.

        2670 Indian Ripple Rd

        Dayton Ohio , 43140

        Office +1.937.427.1231 ext. 292

         

      • Phil Williams
        I will be on. ... -- Philw de KA1GMN
        Message 3 of 3 , Aug 10, 2010
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          I will be on.

          On Tue, Aug 10, 2010 at 12:13 PM, Lehman, Rex <rex.lehman@...> wrote:
           

          Loaded the CMSK last night and was trying it out on 10.139.

          Will be on 10.137 tonight trying CMSK 63.

           

          Rex WB8TDG

           

          Rex Lehman

          Quality Assurance

          Measurement Specialties, Inc.

          2670 Indian Ripple Rd

          Dayton Ohio, 43140

          Office +1.937.427.1231 ext. 292

           




          --
          Philw de KA1GMN
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