WSJT-X version 2.2.0 is now in general availability release, after a short stint in beta (or release candidate) status. WSJT-X version 2.2 offers 10 different protocols or modes — FT4, FT8, JT4, JT9, JT65, QRA64, ISCAT, MSK144, WSPR, and Echo. The first six are designed for reliable contacts under weak-signal conditions, and they use nearly identical message structure and source encoding. JT65 and QRA64 were designed for EME (“moonbounce”) on VHF/UHF bands but have also proven very effective for worldwide very low-power communication on HF bands.
“FT8 is operationally similar but four times faster (15-second T/R [transmit-receive] sequences) and less sensitive by a few decibels,” developer Joe Taylor, K1JT, explains in the version 2.2.0 User Guide. “FT4 is faster still (7.5-second T/R sequences) and especially well suited for contesting.”
Taylor noted that even with their shorter transmit-receive sequences, FT4 and FT8 are considered “slow modes,” because their message frames are sent only once per transmission. “All fast modes in WSJT-X send their message frames repeatedly, as many times as will fit into the [transmit] sequence length,” he explained.
Read more – via American Radio Relay League | Ham Radio Association and Resources https://bit.ly/2MBpPoJ