Hi Joe Built and running - no on-air tests yet.
Noticed that the 15s period is insufficient to get the cw id in. Charlie > Dear Development Colleagues, > > Steve (K9AN) and I have developed a potential new mode for WSJT-X. > We're calling the mode "FT8" (Franke-Taylor design, 8-FSK modulation). > > FT8 is designed for situations like multi-hop Es where signals may be > weak and fading, openings may be short, and you want fast completion of > reliable, confirmable QSOs. > > Important characteristics of FT8: > > - T/R sequence length: 15 s > - Message length: 75 bits + 12-bit CRC > - FEC code: LDPC(174,87) > - Modulation: 8-FSK, keying rate = tone spacing = 5.86 Hz > - Waveform: Continuous phase, constant envelope > - Occupied bandwidth: 47 Hz > - Synchronization: three 7x7 Costas arrays (start, middle, end of Tx) > - Transmission duration: 79*2048/12000 = 13.48 s > - Decoding threshold: -20 dB (perhaps -24 dB with AP decoding, TBD) > - Operational behavior: similar to HF usage of JT9, JT65 > - Multi-decoder: finds and decodes all FT8 signals in passband > - Auto-sequencing after manual start of QSO > > *Comparison with slow modes JT9, JT65, QRA64:* FT8 is a few dB less > sensitive but allows completion of QSOs four times faster. Bandwidth is > greater than JT9, but about 1/4 of JT65A and less than 1/2 QRA64. > > *Comparison with fast modes JT9E-H:* FT8 is significantly more > sensitive, has much smaller bandwidth, uses the vertical waterfall, and > offers multi-decoding over the full displayed passband. > > *Still to come, not yet implemented:* We plan to implement signal > subtraction, two-pass decoding, and use of "a priori" (already known) > information as it accumulates during a QSO. > > Three extra bits are available in the message payload, with uses yet to > be defined. We have in mind special message formats that might be used > in contests, and the like. Your considered suggestions for use of these > bits are very welcome! > > K1JT, K9AN, and G4WJS have conducted on-the-air tests of FT8 with > excellent results. We're now at a stage where tests under a wider range > of conditions are desirable. If you can build WSJT-X from source code > revision r7750 or later, and would like to help, please do so and report > your results to us! Pre-built installation packages will be made > available after further testing is completed. > > Suggestions for FT8 setup and examples of use can be found in a screen > shot posted here: http://physics.princeton.edu/pulsar/k1jt/ft8.png > > We look forward to receiving your feedback. > > -- 73, Joe, K1JT > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > wsjt-devel mailing list > wsjt-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/wsjt-devel > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
