FT8

FT8 is a digital communication mode used in amateur radio designed for reliable two-way contacts under weak signal conditions. It was developed by Joe Taylor (K1JT) and collaborators and introduced in 2017 as part of the WSJT-X software suite. Since its release, FT8 has become one of the most popular weak-signal modes on HF and VHF bands.

Technically, FT8 uses 8-FSK modulation with eight tones spaced 6.25 Hz apart, yielding an approximate 50 Hz bandwidth. Transmissions occur in fixed 15-second time slots synchronized to Coordinated Universal Time (UTC). Each slot carries a short encoded message containing essential contact information, typically including the operator’s callsign and a grid locator, with an optional signal report or brief text. The protocol employs a compact forward error correction and decoding algorithm that maximizes performance in very noisy or fading conditions, allowing decodes down to well below the noise floor.

Operation and use: FT8 is implemented in WSJT-X and is supported by other software such as JTDX. Operators typically tune to a designated FT8 sub-band on a given amateur band, rely on software to synchronize timing, and exchange automatic, semi-structured QSOs. Its efficiency and robustness have driven widespread adoption for quick, high-density contacts, especially during periods of poor propagation.

See also: WSJT-X, JT65, FT4, and other digital modes used in amateur radio.