mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-26 22:28:41 -05:00
81aac15ac6
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8479 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
75 lines
4.2 KiB
Plaintext
75 lines
4.2 KiB
Plaintext
// Status=review
|
||
|
||
_WSJT-X_ is a computer program designed to facilitate basic amateur
|
||
radio communication using very weak signals. The first four letters in
|
||
the program name stand for "`**W**eak **S**ignal communication by
|
||
K1**JT**,`" while the suffix "`-X`" indicates that _WSJT-X_ started as
|
||
an extended and experimental branch of the program
|
||
_WSJT_.
|
||
|
||
_WSJT-X_ Version 1.9 offers nine different protocols or modes: *FT8*,
|
||
*JT4*, *JT9*, *JT65*, *QRA64*, *ISCAT*, *MSK144*, *WSPR*, and *Echo*.
|
||
The first five are designed for making reliable QSOs under extreme
|
||
weak-signal conditions. They use nearly identical message structure
|
||
and source encoding. JT65 and QRA64 were designed for EME
|
||
("`moonbounce`") on the VHF/UHF bands and have also proven very
|
||
effective for worldwide QRP communication on the HF bands. QRA64 has
|
||
a number of advantages over JT65, including better performance on the
|
||
very weakest signals. We imagine that over time it may replace JT65
|
||
for EME use. JT9 was originally designed for the LF, MF, and lower HF
|
||
bands. Its submode JT9A is 2 dB more sensitive than JT65 while using
|
||
less than 10% of the bandwidth. JT4 offers a wide variety of tone
|
||
spacings and has proven highly effective for EME on microwave bands up
|
||
to 24 GHz. These four "`slow`" modes use one-minute timed sequences
|
||
of alternating transmission and reception, so a minimal QSO takes four
|
||
to six minutes — two or three transmissions by each station, one
|
||
sending in odd UTC minutes and the other even. FT8 is operationally
|
||
similar but four times faster (15-second T/R sequences) and less
|
||
sensitive by a few dB. On the HF bands, world-wide QSOs are possible
|
||
with any of these modes using power levels of a few watts (or even
|
||
milliwatts) and compromise antennas. On VHF bands and higher, QSOs
|
||
are possible (by EME and other propagation types) at signal levels 10
|
||
to 15 dB below those required for CW.
|
||
|
||
*ISCAT*, *MSK144*, and optionally submodes *JT9E-H* are "`fast`"
|
||
protocols designed to take advantage of brief signal enhancements from
|
||
ionized meteor trails, aircraft scatter, and other types of scatter
|
||
propagation. These modes use timed sequences of 5, 10, 15, or 30 s
|
||
duration. User messages are transmitted repeatedly at high rate (up
|
||
to 250 characters per second, for MSK144) to make good use of the
|
||
shortest meteor-trail reflections or "`pings`". ISCAT uses free-form
|
||
messages up to 28 characters long, while MSK144 uses the same
|
||
structured messages as the slow modes and optionally an abbreviated
|
||
format with hashed callsigns.
|
||
|
||
*WSPR* (pronounced "`whisper`") stands for **W**eak **S**ignal
|
||
**P**ropagation **R**eporter. The WSPR protocol was designed for probing
|
||
potential propagation paths using low-power transmissions. WSPR
|
||
messages normally carry the transmitting station’s callsign, grid
|
||
locator, and transmitter power in dBm, and they can be decoded at
|
||
signal-to-noise ratios as low as -28 dB in a 2500 Hz bandwidth. WSPR
|
||
users with internet access can automatically upload reception
|
||
reports to a central database called {wsprnet} that provides a mapping
|
||
facility, archival storage, and many other features.
|
||
|
||
*Echo* mode allows you to detect and measure your own station's echoes
|
||
from the moon, even if they are far below the audible threshold.
|
||
|
||
_WSJT-X_ provides spectral displays for receiver passbands as wide as
|
||
5 kHz, flexible rig control for nearly all modern radios used by
|
||
amateurs, and a wide variety of special aids such as automatic Doppler
|
||
tracking for EME QSOs and Echo testing. The program runs equally well
|
||
on Windows, Macintosh, and Linux systems, and installation packages
|
||
are available for all three platforms.
|
||
|
||
*Version Numbers:* _WSJT-X_ release numbers have major, minor, and
|
||
patch numbers separated by periods: for example, _WSJT-X_ Version
|
||
1.9.0. Temporary "`beta`" release candidates are sometimes made in
|
||
advance of a new general-availability release, in order to obtain user
|
||
feedback. For example, version 1.9.0-rc1, 1.9.0-rc2, etc., would
|
||
be beta releases leading up to the final release of v1.9.0.
|
||
Release candidates should be used _only_ during a short testing
|
||
period. They carry an implied obligation to provide feedback to the
|
||
program development group. Candidate releases should not be used on
|
||
the air after a full release with the same number has been made.
|