63 lines
3.4 KiB
Plaintext
63 lines
3.4 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 1.7 offers eight protocols or modes: *JT4*, *JT9*,
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*JT65*, *QRA64*, *ISCAT*, *MSK144*, *WSPR*, and *Echo*. The first
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four are designed for making reliable QSOs under extreme weak-signal
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conditions. They use nearly identical message structure and source
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encoding. JT65 and QRA64 were designed for EME ("`moonbounce`") on
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the VHF/UHF bands and have also proven very effective for worldwide
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QRP communication on the HF bands. QRA64 has a number of advantages
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over JT65, including better performance on the very weakest signals.
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We imagine that over time it may replace JT65 for EME use. JT9 was
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originally designed for the LF, MF, and lower HF bands. Its submode
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JT9A is 2 dB more sensitive than JT65 while using less than 10% of the
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bandwidth. JT4 offers a wide variety of tone spacings and has proven
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highly effective for EME on microwave bands up to 24 GHz. All of these
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"`slow`" modes use one-minute timed sequences of alternating
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transmission and reception, so a minimal QSO takes four to six minutes
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— two or three transmissions by each station, one sending in odd UTC
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minutes and the other even. On the HF bands, world-wide QSOs are
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possible using power levels of a few watts (or even milliwatts) and
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compromise antennas. On VHF bands and higher, QSOs are possible (by
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EME and other propagation types) at signal levels 10 to 15 dB below
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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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