FST4 - WSJT-X
Version 2.3 WSJT-X brings new fashions, which are collectively referred to as FST4. Compared to other modes used so far, they achieve better properties, which are close to the theoretical limits of transmission capacity. They use 4-GFSK modulation with different lengths of T/R sequences 15, 30, 60, 120, 300, 900 a 1800 seconds. Submodes A, B, C and D have a different distance between individual tones. This increases their effectiveness in different propagation and Doppler effect conditions. In principle, FST4 digital modulation should be usable on wavelengths from 2200m to 23cm including EME connections. Do not confuse FST4 with FT4.
FST4W-120A, -300A, -900A, -1800And as a WSPR beacon broadcast for the bands 630 a 2200 m
FST4-120A, -300A, … for connections to 630 a 2200 m bands
FST4-15A for connections by reflection from the ionosphere to 50 MHz
FST4-15A, -30B, -30C, -30D fast (contests?) Make a QSO on 144 – 1296 MHz ?
FST4-120B, -120C, -300C, -300D DO that 50, 144, 432 MHz with the possibility of detecting weak signals
What are the options of FST4?
| T/R period (s) |
Symbol length (s) |
Pitch of tones(Hz) | Occupied width (Hz) |
FST4 SNR (dB) |
FST4W SNR (dB) |
| 15 | 0,060 | 17, | 68, | -21, | -22, |
| 30 | 0,140 | 7, | 29, | -24, | -26, |
| 60 | 0,324 | 3, | 12, | –28,0 | -30, |
| 120 | 0,683 | 1, | 6, | -31, | -33, |
| 300 | 2, | 0,56 | 2, | -35, | -37, |
| 900 | 6, | 0,180 | 0,72 | -40, | -42, |
| 1800 | 11,200 | 0,089 | 0,36 | -43, | -45, |
How to get started with FST4 can be found in the manual https://jl1jvt.cocolog-nifty.com/blog/files/fst4_quick_start.pdf More information about WSJT-X can be found at https://physics.princeton.edu/pulsar/K1JT/wsjtx.html
