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LinWSJT 0.4.7
=============
Introduction
============
This is the Linux versions of JT44, JT6M and FSK441 communications protocols,
usually described together as WSJT. JT44 is used for very weak signal
operation, for example Moonbounce, while FSK441 is specifically designed for
Meteor Scatter. JT6M is a six metre only Meteor Scatter mode, it may very be
useful on 4m also.
Current features are:
FSK441 Transmit
FSK441 Receive
JT44 Transmit
JT44 Receive
JT6M Transmit
JT6M Receive
PTT Control via the Serial Port or no port
Sound Card or .WAV file input and output in 16 or 8-bit mode
GUI front end
Multi-threaded to enable proper timing of the system
Registry for saving options
Logging of messages
My plan is to have a program each for JT44, JT6M and FSK441, which is unlike the
"proper" WSJT program which does both. Unlike the WSJT program, I would not
implement such things as Sun and Moon tracking, that can be done externally.
I want to follow the UNIX ethos of having one program for one job. I do
include a simple Moon tracker in JT44 as it serves a useful purpose there.
Usage
=====
The programs are started by typing either JT44, JT6M or FSK441 at the
command line. "Interesting" messages are send to the file jt44.log, jt6m.log
or fsk441.log respectively, in the current directory. They are useful for
debugging. If you decide to save the messages (the option on the File menu)
then they will be saved in a file named jt44.cum, jt6m.cum or fsk441.cum. If
sound reording is enabled then the generated files are named based on the
date and time: YYYYMMDD_HHMMSS.wav. The real WSJT prefixes the files with
the callsign of the remote station, however if you are simply monitoring
what do you use ?
One of the first things I suggest you do is to change your settings, go into
the Edit menu option and choose Preferences. At a minimum change the
callsign and locator. You may also want to change the sound card and the PTT
details.
The status bar at the bottom of the screen gives information about the audio
level. The program divides the audio into 10 levels, and the normal audio
should be in the range of 3 to 7 with notmal background noise. If the level
is below 1 then no text will be decoded. The program will work outside these
levels. If you receive a very strong JT44, JT6M or FSK441 signal then it is
possible that you will get a message about the signal being too strong,
ignore this. The message about the audio level only appears at the end of a
receiving period, at the same time that the graph is filled in, so be
patient.
Using the program is pretty easy. For simply monitoring leave it as is.
Don't enter a callsign or locator on the main scareen and leave it running
on a suitable requency. NOTE that JT44 requires that your computer clock is
within a couple of seconds of real time otherwise decoding will not occur.
While monitoring, LinWSJT will sometimes decode messages that are gibberish,
that is because LinWSJT does not properly reject any messages no matter how
unrealistic. This is on the TODO list.
To save the sound of the incoming data, press the Record button. It will
stay pressed until you decide to stop recording. The transmit controls are
for the order of transmitting and whether the transmitter is enabled. The
box with the callsign and report are for actually working somebody. These
values (along with values from your preferences) are substituted into the
outgoing messages using the following:
%M - Your callsign
%T - Distant calsign
%L - Your locator
%R - The report
For JT44 the received messages are decoded into a list box, and the odd and
even letters are decoded as well as the average of the last 4 letters. In
the box below the messages box is the averages box, this is where the
average of the messages above is displayed. When signals are very weak and
each transmission contains the same information, then this average will help
in decoding. By default, all newly decoded messages are added into this
average message, it is possible to change this by selecting a message from
from the messages list box by clicking on it with the left mouse button, and
then selecting the popup menu by clicking the right mouse button. This menu
gives the option to Include or Exclude the message from the average message.
If a message is included then a star appears in the S column. It is possible
to force the program to decode a message that is regarded as too weak to
decode by the program. This is achieved by clicking on Decode on the menu.
It is also possible to clear all of the received messages by choosing Clear.
It is also possible to start a new average message by using the right mouse
button in the average message box, this will have the effect of excluding
all of the existing messages from the average message.
For JT44 there is one tunable parameter which is the minimum synchronisation
level, this controls the ability of the program to display extremely weak
signals. A value of 1 is the lowest value that makes any sense to display, a
value of 0 is meaningless and is not allowed. The maximum value is 10 but
should not normally be used. The default value is 1 and I do not advise
changing it except for extreme cases.
For FSK441 and JT6M the information supplied is a little simpler. It
consists of the decoded text and some statistics about it. The only function
available in the messages list box is the ability to delete the decoded
messages. Also unlike JT44, there may be many (or none) lines in the message
list box per receive period depending on the amount of pings and bursts that
you receive and the program can decode.
There are two tunable parameters for FSK441 and JT6M, the minimum length of
burst to display and the minimum strength of ping to display. The values for
the length is in milliseconds and can be from 20ms up to 1000ms, the normal
default is 40ms. Setting this value to small values will mean that bursts of
noise and other random signals will be decoded, even with a value of 40ms it
is possible to see rubbish on the screen. The other values is the minimum
strength of the burst to display, this is from 0dB to 20dB, the default is
2dB. As with the length parameter, the lower the value, the more likely it
is that random data will be decoded.
Finally, the program is able to decode existing WAV files of JT44, JT6M and
FSK441 signals. The W3SZ site has a particularly good set of JT44 files. The
option to do this is on the Edit menu. Once a suitable sound file is found
then it will be processed in the background (as well as the program
simultaneously decoding data from your sound card) and eventually it will
appear in the messages list box which is to be found under the "WAV Files"
tab on the main screen.
I make no guarantees about the program, it may crash, blow your antennas off
the roof, or cause hair to grow out of your radio. But it is a first stage
and any help that you can give would be appreciated.
------------------------------------------------------------------------------
Finally
=======
I need a name for the programs (a general name), I am wondering about LinJT,
LinWS, or LinWSJT, or ...
Suggestions please
I would like to thank the following for code and/or help, or even offers of
help.
Tomi OH2BNS
Kaj OH6EH/1
Axel DF3JRK
Jonathan G4KLX
|
