The latest beta release of the WSJT-X digital software suite includes digital protocols particularly designed for communication on LF and MF bands, such as 2200 meters and 630 meters, and its developers say that during its first few months of testing, contacts have spanned intercontinental paths “many times” on those bands. New protocols FST4 and FST4W are included in WSJT-X version 2.3.0-rc1 (release candidate 1). FST4 is for two-way contacts, while FST4W is for “quasi-beacon” style WSPR transmissions. Both modes offer a range of options for T/R-sequence lengths and threshold decoding sensitivities extending well into the –40 dB range, developers said.
“On these bands, their fundamental sensitivities are better than other WSJT-X modes with the same sequence lengths, approaching the theoretical limits for their rates of information throughput,” the WSJT-X development team said in releasing version 2.3.0-rc1. The developers said, “FST4 and FST4W do not require the strict, independent time-synchronization and phase-locking of modes like EbNaut,” a protocol for VLF and LF communication.
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