The last couple of days I have been playing with a new digital mode called FT-8. I have used it on 6 meters and have made a number of DX contacts using the new mode with low power (25 watts). FT-8 has a much quicker turn-around (4X faster) as compared to the JT-65 and JT-9 modes. This new mode is included in the new beta release of the popular WSJT-X program by the nobel prize winning physicist and ham radio operator Joe Taylor K1JT . This mode like the JT modes is not for chit chatting but really shines in making QSO’s at low power on what appear to be dead bands. It hears what you can’t!!
You can get information and download the the new beta version of WSJT-X here.
Below is a little info primer from Joe K1JT.
“Dear WSJT-X Beta-Test 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 7×7 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 “
testing the new FT8 mode in WSJT-X v1.7.1.To help get things started, we suggest using the following frequencies:Band MHz
Most of these suggestions follow a simple guideline: add 3 kHz to the
commonly used JT65 dial frequency.
For 6 meters we suggest using 50.313, which should be consistent with
band plans in all IARU Regions. (Six meter activity that’s now on
50.276, world-wide, might be moved to 50.310.)
We are very much open to suggestions for changes in the above table.
— 73, Joe, K1JT”