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FMT results from Apr - 2019

k3Timk3Tim Member ✭✭
The Frequency Measurement Test (FMT) results of April 2019 are posted at:

http://fmt.arrl.org/fmtcurresults.php

It's interesting the accuracy with many stations being within 1.0 cycle of the correct frequency. One 6700 based station had an error of -0.01 and -0.07 Hz which seems incredible given effects of propagation. Another Flex station had a 1.00 error using JT65 app for measurement. Being within exactly 1.00 seems like an app error as programmers have problems with zero origin / ones origin values. 

Comments

  • Tom WorthingtonTom Worthington Member ✭✭
    edited May 23
    When I saw my error as 1.00 Hz I was worried that it was an arithmetic mistake by me.  I checked and it was not.  The average of my 46 measurements using WSJT-x was an audio offset of 2031.393 Hz, +/- 2.5 Hz.  I used the API to record the frequency error on receive to be -0.023 Hz. I added that to get the 7,063531.42 MHz that I submitted.
    There was a lot of local lightning, more than last time, and that, I think, increased the scatter in my measurements.  It is at least two bounces off the ionosphere for me here in Hawaii and I don't know of anyway to correct for that.  
    73, Tom, NH6Y
  • k3Timk3Tim Member ✭✭
    edited April 2019
    Perhaps using CHU to see how the 2-hops are affecting the signal.  Correcting for the DDS 'error' was a good idea.

    Next FMT, I'll be running multiple receivers and record WWV on various frequencies and correct the DDS as you mention.  Assume WWVH would wipe out WWV so the propagation effects at your QTH would be lost. 
    There is a station that entered the FMT as a school project and their engineering students for the effort.  The 0.03 / 0.02 score it terrific...

    k3Tim
  • Tom WorthingtonTom Worthington Member ✭✭
    edited April 2019
    I tried listening on 7.335 but all I hear is a Spanish language AM station and it is about 6 Hz off of 7.335.  I would try WWV but all I hear  is WWVB on Kauai.
    73 and Aloha, Tom

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