WSJT

WSJT stands for Weak Signal Joe and is a suite of computer programs developed by Joe Taylor, K1JT, and a team of collaborators, for amateur radio communication. These programs are designed to decode very weak radio signals that would be inaudible to conventional voice or Morse code operators. The primary application of WSJT is for digital modes that enable reliable communication over long distances, often referred to as weak signal propagation.

The original WSJT program focused on a mode called JT4, which was later superseded by other modes like JT65, JT9, and most notably, FT8. FT8 has become extremely popular within the amateur radio community due to its efficiency in weak signal conditions and its ability to exchange call signs and signal reports quickly. These modes work by transmitting and receiving short bursts of digital data encoded in a specific way. The software analyzes these bursts, looking for patterns that match known call signs and messages, even when the signal is buried in background noise.

WSJT modes are particularly useful for weak signal work on the HF bands, where atmospheric conditions can significantly impact signal strength and propagation paths. They allow radio amateurs to make contacts with stations in distant parts of the world that would otherwise be impossible. The programs are open-source and freely available, contributing to their widespread adoption. Beyond simple contacts, WSJT modes are also used for contesting and for monitoring propagation conditions.