44 lines
2.3 KiB
Markdown
44 lines
2.3 KiB
Markdown
# FT8 library
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A C++ implementation of FT8 protocol, mostly intended for experimental use on microcontrollers. At the moment only encoding is implemented.
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The encoding process is relatively light on resources, and an Arduino should be perfectly capable of running this code.
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The intent of this library is to foster experimentation with e.g. automated beacons. FT8 already supports free-text messages and the upcoming new version will support raw telemetry data (71 bits).
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Work is in progress (possibly taking forever) to explore decoding options. On a fast 32-bit microcontroller decoding might be possible, perhaps with some tradeoffs.
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# What works
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So far only encoding is implemented. It should support the basic set of FT8 version 1 (75-bit) messages:
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* CQ {call} {grid}, e.g. CQ CA0LL GG77
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* CQ {xy} {call} {grid}, e.g. CQ JA CA0LL GG77
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* {call} {call} {report}, e.g. CA0LL OT7ER R-07
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* {call} {call} 73/RRR/RR73, e.g. OT7ER CA0LL 73
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* Free-text messages (up to 13 characters from a limited alphabet)
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I am working on the revised FT8 protocol with 77-bit payload (introduced since WSJT-X version 2.0), and currently the library supports the basic message set:
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* CQ {call} {grid}, e.g. CQ CA0LL GG77
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* CQ {xy} {call} {grid}, e.g. CQ JA CA0LL GG77
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* {call} {call} {report}, e.g. CA0LL OT7ER R-07
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* {call} {call} 73/RRR/RR73, e.g. OT7ER CA0LL 73
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# What doesn't
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* Encoding contest mode message
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* Encoding extended range signal reports (<-30dB or >=0dB S/N)
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* Encoding compound callsigns with country prefixes and mode suffixes
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* Decoding
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# What to do with it
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You can generate 15-second WAV files with your own messages as a proof of concept or for testing purposes. They can either be played back or opened directly from WSJT-X. To do that, run ```make``` and build ```gen_ft8```. Then run it. Currently messages are modulated at 1000-1050 Hz.
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# References and credits
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Thanks to Robert Morris, AB1HL, whose Python code (https://github.com/rtmrtmrtmrtm/weakmon) inspired this and helped to test various parts of the code.
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This would not of course be possible without the original WSJT-X code, which is mostly written in Fortran (http://physics.princeton.edu/pulsar/K1JT/wsjtx.html). I believe that is the only 'documentation' of the FT8 protocol available, and the source code was used as such in this project.
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Karlis Goba,
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YL3JG
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