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Tree [d28164] master wsjtx-2.5.4 / History
Joe Taylor
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Copyright (C) 2001 - 2021 by Joe Taylor, K1JT.
WSJT-X Version 2.5 offers eleven different protocols or modes: FT4,
FT8, JT4, JT9, JT65, Q65, FST4, MSK144, WSPR, FST4W, and Echo. The
first seven are designed for making reliable QSOs under weak-signal
conditions. They use nearly identical message structure and source
encoding. JT65 and Q65 were designed for EME (“moonbounce”), but not
limited to just that propagation path, on the VHF/UHF bands and JT65
has also proven very effective for worldwide QRP communication on the
HF bands. Q65 has a number of advantages over JT65, including better
performance on the very weakest signals and variants with different
T/R period lengths. We imagine that over time it may replace JT65 for
EME use, it has also proved to be very effective for iono-scatter
paths on 6m. JT9 was originally designed for the LF, MF, and lower HF
bands. Its submode JT9A is 2 dB more sensitive than JT65 while using
less than 10% of the bandwidth. JT4 offers a wide variety of tone
spacings and has proven highly effective for EME on microwave bands up
to 24 GHz. These four “slow” modes use one-minute timed sequences of
alternating transmission and reception, so a minimal QSO takes four to
six minutes — two or three transmissions by each station, one sending
in odd UTC minutes and the other even. FT8 is operationally similar
but four times faster (15-second T/R sequences) and less sensitive by
a few dB. FT4 is faster still (7.5 s T/R sequences) and especially
well suited for radio contesting. On the HF bands, world-wide QSOs are
possible with any of these modes using power levels of a few watts (or
even milliwatts) and compromise antennas. QSOs are possible at signal
levels 10 to 15 dB below those required for CW. FST4 has similarities
in use to JT9 but offers more flexibility as it offers different
period lengths allowing QSO completion time to be traded off against
sensitivity. In its base form of FST4-60A it has better sensitivity
than JT9A and should be considered as an upgrade where JT9 has been
the preferred slow QSO mode.
Note that even though their T/R sequences are short, FT4 and FT8 are
classified as slow modes because their message frames are sent only
once per transmission. All fast modes in WSJT-X send their message
frames repeatedly, as many times as will fit into the Tx sequence
length.
MSK144, and optionally submodes JT9E-H are “fast” protocols designed
to take advantage of brief signal enhancements from ionized meteor
trails, aircraft scatter, and other types of scatter
propagation. These modes use timed sequences of 5, 10, 15, or 30 s
duration. User messages are transmitted repeatedly at high rate (up to
250 characters per second, for MSK144) to make good use of the
shortest meteor-trail reflections or “pings”. MSK144 uses the same
structured messages as the slow modes and optionally an abbreviated
format with hashed callsigns.
WSPR (pronounced “whisper”) stands for Weak Signal Propagation
Reporter. The WSPR protocol was designed for probing potential
propagation paths using low-power transmissions. WSPR messages
normally carry the transmitting station’s callsign, grid locator, and
transmitter power in dBm, and they can be decoded at signal-to-noise
ratios as low as -31 dB in a 2500 Hz bandwidth. WSPR users with
internet access can automatically upload reception reports to a
central database called WSPRnet that provides a mapping facility,
archival storage, and many other features.
FST4W, like WSPR, is a quasi-beacon mode, it targets LF and MF bands
and offers a number of T/R periods form 2 minutes up to 30 minutes for
the most challenging weak signal paths. Similarly to WSPR reception
reports can be automatically uploaded to the WSPRnet.org web service.
Echo mode allows you to detect and measure your own station’s echoes
from the moon, even if they are far below the audible threshold.
WSJT-X provides spectral displays for receiver passbands as wide as 5
kHz, flexible rig control for nearly all modern radios used by
amateurs, and a wide variety of special aids such as automatic Doppler
tracking for EME QSOs and Echo testing. The program runs equally well
on Windows, Macintosh, and Linux systems, and installation packages
are available for all three platforms.
WSJT-X is an open-source project released under the GPLv3 license (See
COPYING). If you have programming or documentation skills or would
like to contribute to the project in other ways, please make your
interests known to the development team. The project’s source-code
repositories can be found at
https://sourceforge.net/p/wsjt/wsjtx/ci/master/tree/, and
communication among the developers takes place on the email reflector
https://sourceforge.net/p/wsjt/mailman. User-level questions and
answers, and general communication among users is found on the
https://wsjtx.groups.io/g/main email reflector.
Project web site:
https://www.physics.princeton.edu/pulsar/K1JT/wsjtx.html
Project mailing list (shared with other applications from the same
team):
https://sourceforge.net/projects/wsjt/lists/wsjt-devel