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68 lines
4.1 KiB
Plaintext
68 lines
4.1 KiB
Plaintext
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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 K1(JT),`
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while the suffix `-X` indicates that WSJT-X started as an extended and
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experimental branch of the program WSJT.
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.
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WSJT-X Version 2.0 offers twelve different protocols or modes: FST4,
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FST4W, FT4, FT8, JT4, JT9, JT65, QRA64, ISCAT, MSK144, WSPR, and Echo.
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The first eight 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. FST4, and its quasi-beacon companion
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mode FST4W (see below), are designed for LF and MF and offer
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significant advantages over JT9 and WSPR on those bands. JT4 offers a
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wide variety of tone spacings and has proven highly effective for EME
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on microwave bands up to 24 GHz. These four `slow` modes use
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one-minute timed sequences of alternating transmission and reception,
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so a minimal QSO takes four to six minutes — two or three
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transmissions by each station, one sending in odd UTC minutes and the
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other even. FT8 is operationally similar but four times faster
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(15-second T/R sequences) and less sensitive by a few dB. On the HF
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bands, world-wide QSOs are possible with any of these modes using
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power levels of a few watts (or even milliwatts) and compromise
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antennas. On VHF bands and higher, QSOs are possible (by EME and
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other propagation types) at signal levels 10 to 15 dB below those
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required for CW.
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.
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ISCAT, MSK144, and optionally submodes JT9E-H are `fast` protocols
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designed to take advantage of brief signal enhancements from ionized
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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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.
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WSPR (pronounced `whisper`) stands for (W)eak (S)ignal (P)ropagation
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(R)eporter. 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 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. WSPR has a new companion
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FST4W which has a similar message content but offers up to 30 minute
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transmission periods for greater sensitivity on LF and MF.
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.
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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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.
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WSJT-X provides spectral displays for receiver passbands as wide as 5
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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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.
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Be sure to read the online WSJT-X User's Guide.
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