A JT65B EME QSO Answering A Station calling CQ With Computer: Complete Build

This is an example of a real QSO made by EA6VQ that could help understand beginners the right procedure for answering a station who is calling CQ via the Moon. (Please notice that the values of date, time, azimuth, elevation, etc. shown are not the real values but the values when I recreated the QSO from the WAV files in order to make this page)

In this case I knew in advance from the DX-News page that S79HP EME expedition was going to operate on 144.144 MHz, always transmitting the first period (even minutes), so I:

  • Tuned the transceiver to that frequency
  • Entered his callsign and grid in the corresponding input boxes
  • Unchecked the “Tx first” box (as I had to TX second this time)
  • Pressed the “Gen Std Msgs” to generate the messages and have them ready to transmit.
  • Pressed also the “Monitor” button, and waited for some signal.

After some time I began to see a signal in the “SpecJT” window.

When the one-minute period was over, WSJT easily decoded the CQ call of S79HP. So I:

  • Clicked with the mouse on the red spike (that corresponds to the frequency of the JT65B Sync tone) and checked the “Freeze” box. With this simple actions I told the program that I wanted it to concentrate on decoding signals which Sync tone was right on that frequency.
  • Decreased the value of “Tol” to 50 (50 Hz). This is like setting a passband filter of that width, so the program will not take care of other Sync signals, even although you still could see them in the SpecJT window.
  • Made sure that I had “Text 1” selected, that is the right text to send when answering a CQ
  • Set the “Auto” to ON, so that the program would initiate the TX and RX sequencing automatically.

Then, the program shown the new decode…and “bingo”, S79HP had received me and it was sending me the O report (“OOO”). I selected the “Text 3” (RO) to confirm him I had received his “O” report and at the same time send him an “O” report as well. (Please notice that in EME it’s not meaningful to use the RST report because the signals are almost always too weak, so the normal is to exchange an “O” report, meaning that both stations are capable of copying each other.)

WSJT transmitted my “RO” message and then passed to RX again. This time I could see the following in SpecJT.

And when the program decoded it I could see that S79HP had sent “RRR” that is the message confirming he had received my “RO” and so at this point the QSO was complete (An EME QSO is considered complete when one of the stations receives the “RRR”, not before). I selected the “Text 5” (73) as a final courtesy message. Although sending/receiving “73” is not required to consider the QSO as complete but it’s a common practice to send it once, after having received the “RRR” from the partner station. 

Sent the 73 message for only one period and selected “Auto” to OFF in order not to transmit any more on his frequency.. 

Easy, isn’t it?

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