I recently searched the web for a FAX/SSTV program for Linux,
and did not yet find much about that.
Although it is still alpha, and the work has stagnated since
I have very few time to work on it, I want to make my
ACfax project public just for evaluation and development purposes.
Don't expect wonders or much features, but just test it, use it,
and express your experiences and wishes.
I propose to put it under the GNU General Public License,
as free software enables anyone to throw in new ideas and
promotes a project towards better usability.
Just one question - where can I put it up ? (incoming directory on
some ftp-server ?) I have a local ftp server here at my office,
but it may be down some time of day (or better, night).
Also, I would like to have some people helping me with further
implementations. This is a call to all programmers having good
ideas (but please, don't send me a 20,000 lines diff after a while,
I would like to keep track of what happens to the code :-)
Now, some more words about this program :
Requirements:
Athena Widgets (libXaw and Xaw/*.h) to build the program, should
be no problem on X11R5 and X11R6. I use Xaw3d, because it looks
nicer.
SoundBlaster or any compatible device so that the program
can read from /dev/dsp. I use a SB16, this also allows the
/dev/mixer to be accessed.
16 Megabytes of memory "should be enough for everyone" :->
but even less may do if the system is not overloaded.
An 8-bit deep PseudoColor Display (Sorry for this inconvenience,
but I'll extend it for 16 and 24-bit Displays as I have the time)
It should run on a 386DX/33 with ~20% load for continous operation
(program has been developed on such a computer)
Features (or whatever you call it):
AM or FM demodulation possible, adjustable filter width (3 levels),
FM deviation adjustable for contrast adjustment. Uses the
system processor for signal processing (filtering, demodulation).
Grayscale reception with 64 gray levels
Most parameters (except the modem settings) can subsequentially
be adjusted (while or after the image is recieved), because the
demodulated raw data stream is kept in memory.
Image Polarity switch (pos/neg), Phasing polarity switch (pos/neg)
APT tone detection for automatic start/stop (both frequencies
adjustable), automatic phase-in (starts a new image)
Variable IOC for height/width adjustment, variable LPM
Writing direction horizontal/vertical up/down left/right switchable
subsequent image centering and LPM fine correction possible
automatic saving of received images as simple pgm-file
To be done:
Documentation! Actually, there exists nothing but the source code,
or just ask me if it is not clear how to operate. This should be
done first, also for some interna (how does it work, anyway ?)
Transmission of FAX - you will see some preparations in the source
code, and I'll eventually do it.
Color modes for Fax, surely not so easy to implement
Support for displays other than only 8bpp (PseudoColor depth 8)
May be not so easy, as filling colormaps and using color indices
has to be replaced by directly supplying RGB values.
Adjustable image size (by now, the size of the received image is
fixed, and it is placed within a frame with scrollbars)
SSTV would be very nice to have in the same program, if possible,
especially the color modes (Martin1 very popular here in europe)
A level and frequency tuning indicator, e.g. with Xaw-scrollbars
(A simple level indicator displays some numbers on the terminal
upon program startup, but it's only a makeshift)
loading/saving of images in different data formats (not urgent)
...surely much more...
Regards,
Andreas, DL4SDC
Dipl.-Ing. Andreas Czechanowski
qovclxbb@finnmap.com
Institut fuer Netzwerk- und Systemtheorie
Universitaet Stuttgart