• Quicker-Turnaround Digital Modes in Experimental Stage for WSJT-X Suite

    From ARRL de WD1CKS@VERT/WLARB to QST on Thu Jun 15 20:24:10 2017
    06/15/2017

    Recent sporadic-E propagation openings on 6 meters and elsewhere have pointed up the need for a digital mode having faster turnaround time than currently available software versions offer. A recent WSJT-X reflector[1] discussion allowed that, while the slow 'JT modes like JT65 and JT9 have excellent sensitivity, their 1-minute long transmissions may not permit completion of a contact when evanescent signals pop up and quickly disappear under certain E-skip conditions. MSK144 and the fast JT9 submodes allow much shorter transmissions, but they do not offer the multi-decode capability that JT65 users find so effective. Iain MacDonnell, N6ML, was among those remarking that, while the use of JT65 for working E-skip on 6 meters has really taken off, it's too slow to be practical for openings that only last a couple of minutes or so.

    Joe Dzekevich, K1YOW, of Harvard, Massachusetts, sounded a similar theme. "A few days ago we had a great opening on 6 meters, especially here in the New England USA area, given our latitude," he noted. "I often find that often one cannot complete a QSO due to QSB and the ins and outs of Es. Yet, being a propagation buff, I love the idea that I can leave the rig on 50.276 in JT65 mode and then see who I hear throughout the day via PSK Reporter."

    WSJT-X developer Joe Taylor, K1JT, weighed in to express his appreciation to all who shared their ideas and experiences using JT9 and JT65 modes during recent multi-hop E-skip openings on 6 meters.

    "We are very much aware that a mode with most of the excellent characteristics of JT65, but with faster turnaround time, would be a big winner in such situations," Taylor commented on behalf of the WSJT-X development team. "We are experimenting with several such possibilities. Tentative goals include 15-second T/R sequences, sensitivity around S/N = -20 dB, occupied bandwidth less than that of JT65, and capability to decode as many as 10 or 20 signals in a 2-kHz bandwidth."

    But, Taylor added, developing new modes takes a lot of time, and results are not guaranteed. "We will report significant progress if and when available," he pledged.

    According to the WSJT-X page, JT9 is optimized for LF, MF, and HF, and it's some 2 dB more sensitive than JT65 while using less than 10% of the bandwidth. Both JT9 and JT65 permit DX contacts at very low power levels and modest antennas. - Thanks to Joe Taylor, K1JT

     


    [1] https://groups.yahoo.com/neo/groups/wsjtgroup/conversations/topics

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