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Tree [580363] master wsjtx-2.3.0-rc3 / History
Joe Taylor
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Copyright (C) 2001 - 2019 by Joe Taylor, K1JT.
WSJT-X Version 2.1 offers ten different protocols or modes: FT4, FT8,
JT4, JT9, JT65, QRA64, ISCAT, MSK144, WSPR, and Echo. The first six
are designed for making reliable QSOs under weak-signal
conditions. They use nearly identical message structure and source
encoding. JT65 and QRA64 were designed for EME (“moonbounce”) on the
VHF/UHF bands and have also proven very effective for worldwide QRP
communication on the HF bands. QRA64 has a number of advantages over
JT65, including better performance on the very weakest signals. We
imagine that over time it may replace JT65 for EME use. 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.
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.
ISCAT, 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”. ISCAT uses free-form
messages up to 28 characters long, while 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.
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
repository can be found at https://sourceforge.net/projects/wsjt, 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://groups.yahoo.com/neo/groups/wsjtgroup/info 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://groups.yahoo.com/neo/groups/wsjtgroup
