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14Copyright (C) 2001 - 2021 by Joe Taylor, K1JT.
15
16WSJT-X Version 2.5 offers eleven different protocols or modes: FT4,
17FT8, JT4, JT9, JT65, Q65, FST4, MSK144, WSPR, FST4W, and Echo. The
18first seven are designed for making reliable QSOs under weak-signal
19conditions. They use nearly identical message structure and source
20encoding. JT65 and Q65 were designed for EME (“moonbounce”), but not
21limited to just that propagation path, on the VHF/UHF bands and JT65
22has also proven very effective for worldwide QRP communication on the
23HF bands. Q65 has a number of advantages over JT65, including better
24performance on the very weakest signals and variants with different
25T/R period lengths. We imagine that over time it may replace JT65 for
26EME use, it has also proved to be very effective for iono-scatter
27paths on 6m. JT9 was originally designed for the LF, MF, and lower HF
28bands. Its submode JT9A is 2 dB more sensitive than JT65 while using
29less than 10% of the bandwidth. JT4 offers a wide variety of tone
30spacings and has proven highly effective for EME on microwave bands up
31to 24 GHz. These four “slow” modes use one-minute timed sequences of
32alternating transmission and reception, so a minimal QSO takes four to
33six minutes — two or three transmissions by each station, one sending
34in odd UTC minutes and the other even. FT8 is operationally similar
35but four times faster (15-second T/R sequences) and less sensitive by
36a few dB. FT4 is faster still (7.5 s T/R sequences) and especially
37well suited for radio contesting. On the HF bands, world-wide QSOs are
38possible with any of these modes using power levels of a few watts (or
39even milliwatts) and compromise antennas. QSOs are possible at signal
40levels 10 to 15 dB below those required for CW. FST4 has similarities
41in use to JT9 but offers more flexibility as it offers different
42period lengths allowing QSO completion time to be traded off against
43sensitivity. In its base form of FST4-60A it has better sensitivity
44than JT9A and should be considered as an upgrade where JT9 has been
45the preferred slow QSO mode.
46
47Note that even though their T/R sequences are short, FT4 and FT8 are
48classified as slow modes because their message frames are sent only
49once per transmission. All fast modes in WSJT-X send their message
50frames repeatedly, as many times as will fit into the Tx sequence
51length.
52
53MSK144, and optionally submodes JT9E-H are “fast” protocols designed
54to take advantage of brief signal enhancements from ionized meteor
55trails, aircraft scatter, and other types of scatter
56propagation. These modes use timed sequences of 5, 10, 15, or 30 s
57duration. User messages are transmitted repeatedly at high rate (up to
58250 characters per second, for MSK144) to make good use of the
59shortest meteor-trail reflections or “pings”. MSK144 uses the same
60structured messages as the slow modes and optionally an abbreviated
61format with hashed callsigns.
62
63WSPR (pronounced “whisper”) stands for Weak Signal Propagation
64Reporter. The WSPR protocol was designed for probing potential
65propagation paths using low-power transmissions. WSPR messages
66normally carry the transmitting station’s callsign, grid locator, and
67transmitter power in dBm, and they can be decoded at signal-to-noise
68ratios as low as -31 dB in a 2500 Hz bandwidth. WSPR users with
69internet access can automatically upload reception reports to a
70central database called WSPRnet that provides a mapping facility,
71archival storage, and many other features.
72
73FST4W, like WSPR, is a quasi-beacon mode, it targets LF and MF bands
74and offers a number of T/R periods form 2 minutes up to 30 minutes for
75the most challenging weak signal paths. Similarly to WSPR reception
76reports can be automatically uploaded to the WSPRnet.org web service.
77
78Echo mode allows you to detect and measure your own station’s echoes
79from the moon, even if they are far below the audible threshold.
80
81WSJT-X provides spectral displays for receiver passbands as wide as 5
82kHz, flexible rig control for nearly all modern radios used by
83amateurs, and a wide variety of special aids such as automatic Doppler
84tracking for EME QSOs and Echo testing. The program runs equally well
85on Windows, Macintosh, and Linux systems, and installation packages
86are available for all three platforms.
87
88WSJT-X is an open-source project released under the GPLv3 license (See
89COPYING). If you have programming or documentation skills or would
90like to contribute to the project in other ways, please make your
91interests known to the development team. The project’s source-code
92repositories can be found at
93https://sourceforge.net/p/wsjt/wsjtx/ci/master/tree/, and
94communication among the developers takes place on the email reflector
95https://sourceforge.net/p/wsjt/mailman. User-level questions and
96answers, and general communication among users is found on the
97https://wsjtx.groups.io/g/main email reflector.
98
99
100Project web site:
101
102https://www.physics.princeton.edu/pulsar/K1JT/wsjtx.html
103
104Project mailing list (shared with other applications from the same
105team):
106
107https://sourceforge.net/projects/wsjt/lists/wsjt-devel
108