WSJT-X/package_description.txt

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WSJT-X is a computer program designed to facilitate basic amateur
radio communication using very weak signals. The first four letters in
the program name stand for `(W)eak (S)ignal communication by K1(JT),`
while the suffix `-X` indicates that WSJT-X started as an extended and
experimental branch of the program WSJT.
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WSJT-X Version 2.0 offers twelve different protocols or modes: FST4,
FST4W, FT4, FT8, JT4, JT9, JT65, QRA64, ISCAT, MSK144, WSPR, and Echo.
The first eight are designed for making reliable QSOs under extreme
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. FST4, and its quasi-beacon companion
mode FST4W (see below), are designed for LF and MF and offer
significant advantages over JT9 and WSPR on those bands. 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. 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. On VHF bands and higher, QSOs are possible (by EME and
other propagation types) at signal levels 10 to 15 dB below those
required for CW.
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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.
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WSPR (pronounced `whisper`) stands for (W)eak (S)ignal (P)ropagation
(R)eporter. The WSPR protocol was designed for probing potential
propagation paths using low-power transmissions. WSPR messages
normally carry the transmitting stations callsign, grid locator, and
transmitter power in dBm, and they can be decoded at signal-to-noise
ratios as low as -28 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. WSPR has a new companion
FST4W which has a similar message content but offers up to 30 minute
transmission periods for greater sensitivity on LF and MF.
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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.
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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.
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Be sure to read the online WSJT-X User's Guide.