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71 lines
3.9 KiB
Plaintext
71 lines
3.9 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 "`Weak Signal communication by K1JT,`"
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while the suffix "`-X`" indicates that _WSJT-X_ started as an extended
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(and originally experimental) branch of the program _WSJT_.
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_WSJT-X_ Version 1.7 offers eight protocols or "`modes`": *JT4*,
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*JT9*, *JT65*, *QRA64*, *WSPR*, *Echo*, *ISCAT*, and *MSK144*. The
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first four are designed for making reliable QSOs under extreme
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weak-signal conditions. They use nearly identical message structure
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and source encoding. JT65 and QRA64 were designed for EME
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("`moonbounce`") on the VHF/UHF bands and have also proven very
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effective for worldwide QRP communication on the HF bands. QRA64 has
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a number of advantages over JT65, including better performance on the
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very weakest signals. We imagine that over time it will replace JT65
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for EME use. JT9 was designed for the LF, MF, and lower HF bands.
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Its submode JT9A is 2 dB more sensitive than JT65 while using less
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than 10% of the bandwidth. JT4 offers a wide variety of tone spacings
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and has proved very effective for EME on microwave bands up to 24 GHz.
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All of these "`slow`" modes use one-minute timed sequences of
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alternating transmission and reception, so a minimal QSO takes four to
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six minutes — two or three transmissions by each station, one sending
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in odd UTC minutes and the other even. On the HF bands, world-wide
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QSOs are possible using power levels of a few watts (or even
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milliwatts) and compromise antennas. On VHF bands and higher, QSOs
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are possible (by EME and other propagation types) at signal levels 10
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to 15 dB below those required for CW.
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*ISCAT*, *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 and other types of scatter propagation. These
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modes use timed sequences of 5, 10, 15, or 30 s duration. User
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messages are transmitted repeatedly at high rate (up to 250 characters
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per second, for MSK144) to make good use of the shortest meteor
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"`pings`". ISCAT uses free-form messages up to 28 characters long,
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while MSK144 uses the same structured messages as the slow modes
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together with an abbreviated format with hashed callsigns for messages
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sent after initial contact has been established between two stations.
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*WSPR* (pronounced "`whisper`") stands for Weak Signal Propagation
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Reporter. The WSPR protocol was designed for probing potential
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propagation paths using low-power transmissions. WSPR messages
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normally carry the transmitting station’s callsign, grid locator, and
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transmitter power in dBm, and they can be decoded at signal-to-noise
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ratios as low as -28 dB in a 2500 Hz bandwidth. WSPR users with
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internet access can automatically upload their reception reports to a
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central database called {wsprnet} that provides a mapping facility,
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archival storage, and many other features.
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*Echo* mode allows you to detect and measure your own lunar echoes,
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even if they are far below the audible threshold.
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_WSJT-X_ provides spectral displays for passbands up to 5 kHz,
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flexible rig control for nearly all modern radios used by amateurs,
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and a wide variety of special aids such as automatic Doppler tracking
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for EME QSOs and Echo testing. The program runs equally well on
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Windows, Macintosh, and Linux systems, and installation packages are
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available for all three platforms.
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_WSJT-X_ is an open-source project released under the {gnu_gpl}
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(GPL). If you have programming or documentation skills or would like
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to contribute to the project in other ways, please make your interests
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known to the development team. The project’s source-code repository
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can be found at {devsvn}, and most communication among the developers
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takes place on the email reflector {devmail}. User-level questions
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and answers, and general communication among users is found on the
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{wsjt_yahoo_group} email reflector.
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