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92 lines
5.1 KiB
Plaintext
92 lines
5.1 KiB
Plaintext
// Status=review
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_WSJT-X_ is a computer program designed to facilitate basic amateur
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radio communication using very weak signals. The first four letters in
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the program name stand for "`**W**eak **S**ignal communication by
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K1**JT**,`" while the suffix "`*-X*`" indicates that _WSJT-X_ started
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as an extended branch of an earlier program, _WSJT_, first released in
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2001. Bill Somerville, G4WJS, Steve Franke, K9AN, and Nico Palermo,
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IV3NWV, have been major contributors to development of _WSJT-X_ since
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2013, 2015, and 2016, respectively.
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_WSJT-X_ Version {VERSION_MAJOR}.{VERSION_MINOR} offers eleven
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different protocols or modes: *FST4*, *FT4*, *FT8*, *JT4*, *JT9*,
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*JT65*, *Q65*, *MSK144*, *WSPR*, *FST4W*, and *Echo*. The first seven
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are designed for making reliable QSOs under weak-signal
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conditions. They use nearly identical message structure and source
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encoding. JT65 was designed for EME ("`moonbounce`") on VHF and
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higher bands and is mostly used for that purpose today. Q65 is
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particularly effective for tropospheric scatter, rain scatter,
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ionospheric scatter, TEP, and EME on VHF and higher bands, as well as
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other types of fast-fading signals. JT9 was designed for the HF and
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lower bands. Its submode JT9A is 1 dB more sensitive than JT65 while
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using less than 10% of the bandwidth. JT4 offers a wide variety of
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tone spacings and has proven highly effective for EME on microwave
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bands up to 24 GHz. The "`slow`" modes use timed sequences of
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alternating transmission and reception. JT4, JT9, and JT65 use
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one-minute sequences, so a minimal QSO takes four to six minutes — two
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or three transmissions by each station, one sending in odd UTC minutes
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and the other even. FT8 is four times faster (15-second T/R
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sequences) and less sensitive by a few dB. FT4 is faster still (7.5 s
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T/R sequences) and especially well-suited for radio contesting. FST4
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is designed especially for the LF and MF bands. Both FST4 and Q65
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offer a wide variety of timed sequence lengths, and Q65 a range of
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tone spacings for different propagation conditions. On the HF bands,
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world-wide QSOs are possible with any of these modes using power
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levels of a few watts (or even milliwatts) and compromise antennas.
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On VHF bands and higher, QSOs are possible (by EME, scatter, and other
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propagation types) at signal levels 10 to 15 dB below those required
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for CW.
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*MSK144*, and optionally submodes *JT9E-H* are "`fast`"
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protocols designed to take advantage of brief signal enhancements from
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ionized meteor trails, aircraft scatter, and other types of scatter
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propagation. These modes use timed sequences of 5, 10, 15, or 30 s
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duration. User messages are transmitted repeatedly at high rate (up
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to 250 characters per second for MSK144) to make good use of the
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shortest meteor-trail reflections or "`pings`". MSK144 uses the same
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structured messages as the slow modes and optionally an abbreviated
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format with hashed callsigns.
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Note that some of the modes classified as slow can have T/R sequence
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lengths as short the fast modes. "`Slow`" in this sense implies
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message frames being sent only once per transmission. The fast modes
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in _WSJT-X_ send their message frames repeatedly, as many times as
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will fit into the Tx sequence length.
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*WSPR* (pronounced "`whisper`") stands for **W**eak **S**ignal
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**P**ropagation **R**eporter. The WSPR protocol was designed for
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probing potential propagation paths using low-power transmissions.
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WSPR messages normally carry the transmitting station’s callsign,
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grid locator, and transmitter power in dBm, and with two-minute
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sequences they can be decoded at signal-to-noise ratios as low
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as -31 dB in a 2500 Hz bandwidth. *FST4W* is designed for
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similar purposes, but especially for use on LF and MF bands.
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It includes optional sequence lengths as long as 30 minutes and
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reaches sensitivity tresholds as low as -45 dB. Users
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with internet access can automatically upload WSPR and FST4W
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reception reports to a central database called {wsprnet} that
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provides a mapping facility, archival storage, and many other
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features.
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*Echo* mode allows you to detect and measure your own station's echoes
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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
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5 kHz, flexible rig control for nearly all modern radios used by
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amateurs, and a wide variety of special aids such as automatic Doppler
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tracking for EME QSOs and Echo testing. The program runs equally well
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on Windows, Macintosh, and Linux systems, and installation packages
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are available for all three platforms.
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*Version Numbers:* _WSJT-X_ release numbers have major, minor, and
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patch numbers separated by periods: for example, _WSJT-X_ Version
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2.1.0. Temporary _beta release_ candidates are sometimes made in
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advance of a new general-availability release, in order to obtain user
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feedback. For example, version 2.1.0-rc1, 2.1.0-rc2, etc., would
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be beta releases leading up to the final release of v2.1.0.
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Release candidates should be used _only_ during a short testing
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period. They carry an implied obligation to provide feedback to the
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program development group. Candidate releases should not be used on
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the air after a full release with the same number is made.
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