WSJT-X: New in Version 2.3.0
The WSJT Development Group has announced the general availability release of WSJT-X Version 2.3.0. WSJT-X 2.3.0 General Availability release adds the new modes FST4 and FST4W along with many defect repairs. See summaries below and for the prior release candidates (2.3.0-rc1 through -rc4) of this version for details. - FST4/W: Disable envelope shaping at start and end of transmission when environment variable FST4_NOSHAPING=1. Works for fst4sim too. - Add time stamp to error message boxes to aid diagnosis. - Repair a defect that caused crashes at start up for some macOS Big Sur users. - Repair a defect that could cause the jt9 slow mode decoder process to exit incorrectly with a failure status. - Updated CTY.DAT file. WSJT-X: New in Version 2.3.0 WSJT-X 2.3.0 introduces FST4 and FST4W, new digital protocols designed particularly for the LF and MF bands. Decoders for these modes can take advantage of the very small Doppler spreads present at these frequencies, even over intercontinental distances. As a consequence, fundamental sensitivities of FST4 and FST4W are better than other WSJT-X modes with the same sequence lengths, approaching the theoretical limits for their rates of information throughput. The FST4 protocol is optimized for two-way QSOs, while FST4W is for quasi-beacon transmissions of WSPR-style messages. FST4 and FST4W do not require the strict, independent phase locking and time synchronization of modes like EbNaut. The new modes use 4-GFSK modulation and share common software for encoding and decoding messages. FST4 offers T/R sequence lengths of 15, 30, 60, 120, 300, 900, and 1800 seconds, while FST4W omits the lengths shorter than 120 s. Submodes are given names like FST4-60, FST4W-300, etc., the appended numbers indicating sequence length in seconds. Message payloads contain either 77 bits, as in FT4, FT8, and MSK144, or 50 bits for the WSPR-like messages of FST4W. Message formats displayed to the user are like those in the other 77-bit and 50-bit modes in WSJT-X. Forward error correction uses a low density parity check (LDPC) code with 240 information and parity bits. Transmissions consist of 160 symbols: 120 information-carrying symbols of two bits each, interspersed with five groups of eight predefined synchronization symbols. We recommend that on the 2200 and 630 m bands FST4 should replace JT9 for making 2-way QSOs, and FST4W should replace WSPR for propagation tests. Operating conventions on these LF and MF bands will eventually determine the most useful T/R sequence lengths for each type of operation.
WSJT-X is a computer program designed to facilitate basic amateur radio communication using very weak signals.
WSJT-X Version 2.3 offers ten different protocols or modes: FT4, FST4 and FST4W, FT8, JT4, JT9, JT65, QRA64, ISCAT, MSK144, WSPR, and Echo. The first eight are designed for making reliable QSOs under weak-signal conditions. They use nearly identical message structure and source encoding. JT65 and QRA64 were designed for EME (“moonbounce”) on the VHF/UHF bands and have also proven very effective for worldwide QRP communication on the HF bands