mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-18 18:12:12 -05:00
a4185e0665
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7241 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
63 lines
3.4 KiB
Plaintext
63 lines
3.4 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 1.7 offers eight protocols or modes: *JT4*, *JT9*,
|
||
*JT65*, *QRA64*, *ISCAT*, *MSK144*, *WSPR*, and *Echo*. The first
|
||
four 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. All of these
|
||
"`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. On the HF bands, world-wide QSOs are
|
||
possible 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.
|
||
|