65 lines
3.6 KiB
Plaintext
65 lines
3.6 KiB
Plaintext
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// 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 as
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an extended and experimental branch of the program
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_WSJT_.
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_WSJT-X_ Version 1.8 offers nine different protocols or modes: *FT8*,
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*JT4*, *JT9*, *JT65*, *QRA64*, *ISCAT*, *MSK144*, *WSPR*, and *Echo*.
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The first five 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 may replace JT65
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for EME use. JT9 was originally designed for the LF, MF, and lower HF
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bands. Its submode JT9A is 2 dB more sensitive than JT65 while using
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less than 10% of the bandwidth. JT4 offers a wide variety of tone
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spacings and has proven highly effective for EME on microwave bands up
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to 24 GHz. These four "`slow`" modes use one-minute timed sequences
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of alternating transmission and reception, so a minimal QSO takes four
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to six minutes — two or three transmissions by each station, one
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sending in odd UTC minutes and the other even. FT8 is operationally
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similar but four times faster (15-second T/R sequences) and less
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sensitive by a few dB. On the HF bands, world-wide QSOs are possible
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with any of these modes 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, 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`". ISCAT uses free-form
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messages up to 28 characters long, while 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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*WSPR* (pronounced "`whisper`") stands for **W**eak **S**ignal
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**P**ropagation **R**eporter. The WSPR protocol was designed for probing
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potential propagation paths using low-power transmissions. WSPR
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messages normally carry the transmitting station’s callsign, grid
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locator, and transmitter power in dBm, and they can be decoded at
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signal-to-noise ratios as low as -28 dB in a 2500 Hz bandwidth. WSPR
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users with internet access can automatically upload reception
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reports to a central database called {wsprnet} that provides a mapping
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facility, archival storage, and many other 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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