What is FT4 in Ham Radio?

What is FT4 in Ham Radio?

FT4 is a digital mode of communication in Ham Radio meant for contesting, developed by Joe Taylor, K1JT and Steve Franke, K9AN, the same persons who developed FT8 for weak signal communication. FT4 signals can be decoded using WSJT-X software discussed earlier. FT4 is similar to FT8, but faster, and was introduced in 2019. Information exchanged in FT4 and FT8 include calls signs, four character Maidenhead grid locators, signal reports and acknowledgements. Six second transmit-receive sequences make it 2.5 times faster than FT8. In case of FT4, transmitted data lasts for 4.48 seconds compared to 12.64 seconds for FT8.

FT4 has features which can determine the best potential QSO from a contesting perspective. It can determine the best potential QSO partner, giving first priority for a new multiplier and second priority for a new call on band, among the CQ calls received. FT4 uses four tone frequency shift keying and occupies a bandwidth of 90 Hz compared to the 50 Hz bandwidth of FT8. Compared to RTTY (Radioteletype), FT4 can work with signals 10 dB weaker while requiring much less bandwidth.