New Digital Mode From K1JT – FT8


FT8-band-scope
FT8-QSO

Steve(K9AN) and Joe(K1JT) have developed a potential new mode for WSJT-X. They are 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.

In addition Joe said:

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 “

 A short list of new features and capabilities (including the new FT8 and FreqCal modes) can be found in the Release Notes for WSJT-X:
http://physics.princeton.edu/pulsar/K1JT/Release_Notes_1.8.0.txt

To get started with this new mode (FT8) you can grab the installation packages for WSJT-X Version 1.8 or better.  Packages for Windows, Linux, OS X, and Raspbian Jessie and be downloaded from the WSJT web site at:
http://physics.princeton.edu/pulsar/K1JT/wsjtx.html 

Be aware: this mode is very new – as of 7/15/2017,  both eQSL, LoTW and QRZ are not accepting FT8 as a valid mode – they are aware of the new mode and proper notification has been dispatched to those who run those sites.  While it’s not known what the ETA is on getting FT8 added, it will be published on the Internet.  Keep in mind WSJT-X Software Release Candidates may still have bugs so be prepared to report those if they come up.

There is also a Facebook Group you can join for additional info and collaboration.

13 thoughts on “New Digital Mode From K1JT – FT8

  1. I see that you have the ‘already worked’ showing up in green. That’s great except that a contact I made on 20M is showing up green on 40M and I haven’t yet worked him on 40M.
    Also a station I’m trying to contact responds with ‘spread up’. So I guess that they are running split. Is there a standard offset to run FT8 split?

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  2. This mode is absolutely great and fascinating. To get on the air so simply and work the world is wonderful. I thing in the month I’ve used it I’ve learn so much about propagation and how to bring in the foreign stations where the signals calling him must be in the hundreds. I was on WSPR for a couple of years and that really elevated my interest for making this a QSO mode. Thanks to all. Ron K7UV, Utah

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  3. Hi

    I have a really poor take off here, so digital modes ideal for me

    Trying FT8 and so far great results!

    No problem downloading as it updates my previous version automatically

    Thank you guys for great programme

    73

    Alan
    G4GQL

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  4. Love the new mode! After JT65, it feels like I need to fasten my seat belt, or be left behind! I do miss the frequency list on the left. Didn’t there used to be a pull-down? You know, click on 20m and it reminds you of the “usual” frequency to use for the mode? I really miss that in the middle of the night when I am only firing on 3 cylinders! Keep up the good work. You guys are the personification of amateur radio expanding the art and science of radio communication!

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  5. Have been enjoying FT8 now for just a week. Getting local hams to get on FT8. Like it when 6M opens up more. Question: how can you tell that you have worked someone before, just like we do on JT65? Is it going to be put into the next update? Guess I could use N1MM to check for dups. Just curious. Thanks.

    Jim, W6NIF
    Fresno, Ca.

    Liked by 1 person

  6. Great mode, with a very good uptake across the globe so far. I will have to suspend use of the mode, though, until LoTW fix their non-acceptance – just too many QSOs to manually log!

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  7. London Amateur Radio Club ran FT8 at our Special Event station VX3LON on Jul 15-16. Made several QSO on really bad band conditions. Great to be on the cutting edge for a change. Thank you guys for keeping up what we in Canada used to call the “Amateur Experimental Service”.
    73 Mike CG3ACW

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