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FT8 DXpedition Mode Field Test Attracts Upward of 500 Participants


It was the Fox and the Hounds on the bands March 6, as the WSJT-X development group conducted a field test of the still-beta FT8 DXpedition Mode. A second beta version of WSJT-X version 1.9.0, which includes the DXpedition-mode-capable version of FT8 — was released recently. Version 1.9.0-rc2 was made available to allow further field testing of the FT8 DXpedition mode, which is designed to permit DXpeditions to make FT8 contacts at very high rates. Developer Joe Taylor — the “T” in FT8 — has released a few highlights drawn from his observations during the public test. The “Fox” is the DXpedition station, while “Hounds” comprise the pileup.

According to the FT8 DXpedition Mode User Guide, contacts between the DXpedition station and callers can be completed in as little as one transmission apiece by the calling station. DXpedition stations can transmit up to five signals simultaneously, allowing contact rates up to about 500 per hour, under ideal conditions.

“The overwhelming majority of participating Hounds operated as intended, and according to instructions,” Taylor said. “I copied 190 unique Hound call signs during the 2300 [UTC] hour — when I was acting as Fox on 20 meters — and 330 unique call signs during the whole 4 hours. I suppose that we had at least 400 – 500 participants, maybe more.”

Other observations:

  • Fox’s multi-signal capability worked very well at the tested values, NSlots = 3, 4, and 5. “This feature is surely a keeper, and I see no reason not to use NSlots = 5 — especially if the Fox is running power,” Taylor said.

  • In the 4 test hours, the number of contacts logged by Foxes on 20, 30, 40, and 80 meters was 320, 189, 454, and 351, respectively. “However, a regrettable program bug was preventing deletion of Hound call signs from Fox’s ‘QSO-in-Progress’ list after a QSO had been logged,” Taylor explained. “As a result, many repeated ‘RR73’ messages were sent, many dupe QSOs were logged, and the ‘QSO-in-Progress’ list kept growing. As another consequence, some QSOs took up to about 20 min to complete, and a number of Hounds who had been sent a report never received their QSO-confirming ‘RR73.’”

  • AA7A worked 120 unique call signs in the 40-meter hour, and the other Foxes worked comparable, slightly lower numbers. When this program bug is corrected, hourly contacts in the 300 – 400 range should certainly be achievable.

  • Some Hounds did not operate as intended. “Several kept trying to raise Fox by calling below 1,000 Hz,” Taylor said, adding that most of these stations he noticed were in non-English speaking countries. He suggested translations of the FT8 DXpedition Mode User Guide may be needed.

  • A few would-be Hounds were obviously not using version 1.9.0-rc2, and were calling Fox blind in first sequence. A few Hounds tried using compound call signs, which is not supported, “and which needs to be made more clear in the instructions,” Taylor said.

Taylor recommended two operating hints that should be used as needed, but, in general, were not used during the March 6 public test:

  • Hounds should manually reset their TX frequency as needed to evade human-generated interference.

  • Fox may decide to use the randomizing feature to vary TX frequency.

Some relatively minor bugs and other things came to light during the test run:

  • Spurious “call sign mismatch” warning messages were displayed to the Fox operator.

  • Fox’s log window should automatically scroll to the bottom (or maybe it should simply show the most recent ~10 contacts logged).

  • Fox’s “Max Calls” parameter may not have worked as designed.

  • Sometimes Fox sent “RR73” to the same station in more than one slot, in the same transmission.

  • Some users saw the dreaded “Blue Decode” button.

  • Hounds sometimes send a spuriously low-signal report to Fox, even when Fox is loud.

  • If Hound hits “Enter” with the DX Call box empty, a blank message can be transmitted.

  • If a random station (not Fox) calls a Hound, it can trigger a Hound transmission, just as if Fox had called.

  • Previously decoded Hound call signs can sometimes reappear in Fox’s left window, when they should not.

Taylor outlined a few new features the development team may decide to implement:

  • Possibly as an option for debugging, a display window that shows the Fox operator the contents of all active queues is being considered.

  • Limit the number of contacts-in-progress to no more than NSlots.

  • Include an option to suppress display of the waterfall timestamp.

  • Have Fox call CQ in one slot at least once every few minutes.

  • Taylor asked, “Should Hound’s TX3 frequency be re-randomized for each repeat try?”

He said that depending on programming progress and his own schedule, the development team may schedule another public test in a few weeks.

Installation packages for Windows, Linux, macOS, and Raspbian Jessie have been posted on the WSJT website.

Taylor told ARRL earlier this year that the goal is to have the official release of WSJT-X version 1.9.0 finished, documented, and thoroughly tested, well in advance of the planned KH1/KH7Z DXpedition to Baker Island in June. General availability of the official WSJT-X version 1.9.0 will be announced “in the near future,” the development group said.




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