mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-22 04:11:16 -05:00
13ffbb20eb
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7079 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
110 lines
5.2 KiB
Plaintext
110 lines
5.2 KiB
Plaintext
Alpha Release: WSJT-X Version 1.7
|
|
---------------------------------
|
|
|
|
Short list of new features
|
|
--------------------------
|
|
1. New modes: ISCAT, MSK144, QRA64.
|
|
2. Newly implemented submodes: JT65B-C, JT9B-H (wide and fast).
|
|
3. FT decoder replaces KV decoder for JT65; KVASD is no longer used.
|
|
4. Improvements to JT4, JT9, and JT65 decoders.
|
|
5. Multi-pass decoding for JT65 and WSPR.
|
|
6. Many improvements to Rig Control.
|
|
7. Improved convenience features for EME Doppler tracking.
|
|
8. Multiple configurations can be saved and restored.
|
|
9. Sample-file download facility.
|
|
10. Optional auto-sequencing for "fast" modes.
|
|
|
|
New Modes
|
|
---------
|
|
1. MSK144 is intended for meteor scatter at 50 MHz and higher.
|
|
Designed and tested by K9AN and K1JT, it uses a low-density parity
|
|
check code (LDPC) -- one of the latest-and-greatest areas of active
|
|
research in communication theory.
|
|
|
|
MSK144 is a direct descendant of the now-defunct mode JTMSK, with a
|
|
number of improvements for better performance on weak and short meteor
|
|
pings. The effective character transmission rate is about 250 cps,
|
|
compared with 147 cps for FSK441 and 154 cps for JTMSK. Like JT4,
|
|
JT9, JT65, and JTMSK, MSK144 uses strong forward error correction, so
|
|
message decoding is essentially "all or nothing". You will see little
|
|
or no garbage on your screen.
|
|
|
|
Standard MSK144 message frames are 72 ms long, compared to 117 ms for
|
|
JTMSK. The MSK144 waveform allows coherent demodulation, allowing up
|
|
to 3 dB better sensitivity. After QSO partners have exchanged
|
|
callsigns, MSK144 can use even shorter messages, only 20 ms long. As
|
|
in all the fast modes in WSJT-X, the 20 ms or 72 ms messages are
|
|
repeated without gaps for the duration of a transmission cycle. For
|
|
most purposes we recommend a T/R cycle duration of 15 s, but 5 s and
|
|
10 s sequences are also supported.
|
|
|
|
Short ("Sh") messages in MSK144 are intended primarily for 144 MHz,
|
|
where most pings are short. These messages do not contain full
|
|
callsigns; instead, they contain a hash of the entire transmitted
|
|
message along with a report. They are not encrypted -- the report is
|
|
sent in the clear along with the hash. Short messages are fully
|
|
decodable only by the station to whom they are addressed, as part of
|
|
an ongoing QSO, because only then will the received hash match that
|
|
calculated using the known strings for "My Call" and "DX Call" and the
|
|
received report, RRR, or 73. If you are monitoring someone else's
|
|
QSO, you will not be able to decode its Sh messages.
|
|
|
|
An MSK144 signal occupies the full bandwidth of a typical SSB
|
|
transmitter, so transmissions are always centered at an offset of
|
|
1500Hz. For best results, selectable/adjustable Rx and Tx filters
|
|
should be set to provide the flattest possible response over at least
|
|
300 - 2700 Hz. The maximum permissible frequency offset between you
|
|
and your QSO partner is 200 Hz, and less is better.
|
|
|
|
2. QRA64 is a intended for EME and other weak-signal use. Its
|
|
internal code was designed by Nico Palermo, IV3NWV, and implemented in
|
|
WSJT-X by K1JT. The protocol uses a "Q-ary Repeat Accumulate" code,
|
|
another one of the latest research areas in communication theory. The
|
|
QRA64 code is inherently better than the Reed Solomon (63,12) code
|
|
used in JT65, yielding already a 1.3 dB advantage. QRA64 uses a new
|
|
synchronizing scheme based on a 7 x 7 Costas array, so you will not
|
|
see a bright sync tone at the lowest tone frequency. This change
|
|
yields another 1.9 dB advantage.
|
|
|
|
In most respects our implementation of QRA64 is operationally similar
|
|
to JT65. QRA64 does not use two-tone shorthand messages, and it makes
|
|
no use of a callsign database. Rather, additional sensitivity is
|
|
gained by making use of "already known" information as a QSO
|
|
progresses -- for example, when reports are being exchanged and you
|
|
have already decoded both callsigns in a previous transmission. QRA64
|
|
presently offers no message averaging capability, though that may be
|
|
added. In our early tests, many EME QSOs have already been made using
|
|
submodes QRA64A-E on bands from 144 MHz to 10 GHz.
|
|
|
|
3. ISCAT is essentially the same as in recent versions of program WSJT.
|
|
For details consult the WSJT User Guide:
|
|
http://physics.princeton.edu/pulsar/K1JT/doc/wsjt/
|
|
|
|
|
|
Program Setup
|
|
-------------
|
|
|
|
Many of the new program capabilities are enabled when you check
|
|
"Enable VHF/UHF/Microwave features" on the Settings | General tab.
|
|
For MSK144 mode, we suggest setting "T/R 15 s" and "F Tol 100 Hz".
|
|
Check "Sh" to enable the use of short messages and "Auto Seq" for
|
|
auto-sequencing. For QRA64 mode, set Tx and Rx frequencies to 1000
|
|
Hz. We encourage you to check "Save all" when making tests, and to
|
|
save any of the resulting .wav files that might help us to improve
|
|
program performance or behavior, or to illustrate a problem that you
|
|
identify.
|
|
|
|
|
|
Final Comments
|
|
--------------
|
|
|
|
Remember that you are using an Alpha Release. We will be grateful for
|
|
any and all reports from test users that may help us to further
|
|
improve WSJT-X. The most helpful reports describe the problem clearly
|
|
and include a complete recipe to reproduce it. Send your reports to
|
|
wsjtgroup@yahoogroups.com.
|
|
|
|
Please be patient concerning responses from the development group.
|
|
Several of us will be on vacation or otherwise engaged during much of
|
|
August.
|