This is an old revision of this page, as edited by Qslcard (talk | contribs) at 06:09, 30 January 2022. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 06:09, 30 January 2022 by Qslcard (talk | contribs)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)FT8 is a popular amateur radio digital mode. The most widely used FT8 software is WSJT-X. It is widely used on the shortwave (high frequency/HF) bands. The exchange consists of call signs, signal-to-noise ratios, and Maidenhead Locator System grid squares.
Joe Taylor, K1JT, announced on June 29, 2017, the availability of FT8 in WSJT-X. FT8 stands for "Franke-Taylor design, 8-FSK modulation" and was created by Joe Taylor, K1JT and Steve Franke, K9AN. It is described as being designed for "multi-hop Es where signals may be weak and fading, openings may be short, and you want fast completion of reliable, confirmable QSO's".
According to Taylor, the important characteristics of FT8 are —
- T/R sequence length: 15 s
- Message length: 75 bits + 12-bit CRC
- FEC code: (174,87) LDPC
- Modulation: 8-FSK, keying rate = tone spacing = 6.25 Hz
- Waveform: Continuous phase, constant envelope
- Occupied bandwidth: 50 Hz
- Synchronization: three 7x7 Costas arrays (start, middle, end of transmission)
- Transmission duration: 79*1920/12000 = 12.64 s
- Decoding threshold: -24 dB (with decoding)
- Operational behavior: similar to HF usage of JT9, JT65
- Multi-decoder: finds and decodes all FT8 signals in passband
- Auto-sequencing after manual start of QSO
Compared to the so-called "slow modes" (JT9, JT65, QRA64), FT8 is a few decibels less sensitive, but allows completion of QSOs four times faster. Bandwidth is greater than JT9, but about one-quarter of JT65A and less than one-half of QRA64. Compared with the "fast modes" (JT9E-H), FT8 is significantly more sensitive, has much narrower bandwidth, uses the vertical waterfall, and offers multi-decoding over the full displayed passband. Features not yet implemented include signal subtraction, two-pass decoding, and use of a priori (already known) information as it accumulates during a QSO."
- "FT8 Mode is Latest Bright Shiny Object in Amateur Radio Digital World". American Radio Relay League (ARRL). 2017-08-01.
- Joe Taylor, K1JT. "FT8".
{{cite web}}: CS1 maint: numeric names: authors list (link)