WEFAX ON THE ATARI

                          instructions

This  program  enables  the user to  display  and  save  pictures  
received from a radio and a Kantronics TNC.  

To  use  the TNC has to be connected to the radio and  the  Atari  
computer  in  the manner given in the  instructions.   The  RS232  
cable  needs the receive and transmit data lines connect as  well  
as  the  clear to send and ready to send and  earth.   The  atari  
computer and the TNC should be set to the same baud rate of 4800.  
This  is  done by using a standard packet program or  a  terminal  
emulator  on the atari and set the baud rate on the TNC  to  4800  
with the command "ABAUD 4800" followed by "RESET".  This puts the  
TNC  to  4800 baud.  The computer is then put to  4800  baud,  no  
parity, 8 bits, one stop bit and the rts/cts hardware handshaking  
should be enabled. Software (xon/xoff) should be disabled.

The  Wefax program (called FACPROC.PRG) is run and the  user  can  
run  through  a series of choices with  alert  boxes.  The  first  
choice  is made by the computer as it checkes the  RAM  size,  if  
there is less then 300K the program will exit,  also it will  exit  
if  the  display  is not high  definition  monochrome.  The  full  
version  requires 2MB but the program will detect the  amount  of  
memory  and will run a smaller image size for  smaller  machines.   
The large version which needs 2MB uses all the lines output  from  
the  WEFAX  station,  the small version uses 1 in 2 lines  and  a  
smaller  sampling rate,  giving a smaller image.   This does  not  
substantially reduce the quality of the printed output. 

When the choice "TNC ready" is displayed the choice "YES"  should  
be followed be turning the TNC on.

There  follows a series of self explanatory choices and when  the  
picture  is  complete then "F9 to save or  abort"  is  displayed.  
When you have clicked on "OK" then the function keys are enabled. 
F2  inverses  black to white,  F5 makes a  mirror  inversion,  F9  
enables  the user to save the image or exit.  The left and  right  
arrow  keys rotate the image across the screen so that the  image  
moves off to the left or right and reappears on the other end  of  
the  picture.  F10  rotates  the  image  through  a  right  angle 
clockwise  and  F8 rotates the image  anticlockwise  through  one 
right angle.

If the begining of an image is missed then F1 will force a  start  
and  similarly F3 will force a stop.  F6 will abort  the  receive  
process  and  give a choice of waiting for the  synch  signal  or  
aborting.

The   mouse will move the window to another part of  the  picture  
and when the option to "Save" is selected after pressing F9 there  
is  a choice of a snapshot of the picture,  the area selected  by  
the  mouse,  the  whole  image or a degas save  of  the  display.   
Otherwise a GEM paint compatable .IMG file is produced.  This IMG  
file  is not compressed and can take up to 650K approx  (for  the  
large option) but the usual size of WEFAX images is about 180K or  
less.  The DEGAS file is always the same at 32K.

The .IMG file can be loaded into "HYPERPAINT" or  "TIMEWORKS.DTP"  
and other packages that can accept GEM.IMG files.

The  save  routine  has been improved and  takes  only  about  2  
second to save the largest file with a hard disk but longer on a  
floppy.  Loading  an image is quite lengthy and can take  several  
seconds,  similarly,  the  rotate  instruction can take  about  1  
minute.  The  other  commands  take less time,  but  there  is  a  
noticable  delay while nothing appears to  happen.   Please  make  
sure  the  mouse  is away from the edge of the  screen  when  any  
option  is  selected as its proximity to the edge may  cause  the  
instruction to be ignored.

There is also an auto-save option and up to 99 whole frame images  
can  be saved in succession automatically.   A file selector  box  
appears and you choose the file name,  the file extension is then  
given automatically as ".001, .002 ... .099" whatever is written.

Stations transmitting WEFAX can be found on 132.7KHz  (Offenbach)  
4780.3 KHz,  7878.3 KHz,  (all USB),  and several others.   A VLF  
converter   is   useful  for  the   LF   stations.   (Approximate  
frequencies).

Note:- do not enter the WEFAX mode on the TNC as the program will  
do this automatically.

Note:- In the larger machines,  there is a choice between "small"  
and "large" this refers to the width of the received image.   The  
narrow image is the 960 pixels,  the wide image is 1280 pixels in  
width.   When the image is loaded into "Timeworks.DTP" the  image  
can be made in the correct proportion by selecting the  "preserve  
aspect  ratio" option in timeworks as the image is saved  in  the  
correct aspect ratio in both cases. The large version has a total  
image  size  of 2280 by 2280 pixels so although this is  not  all  
used by WEFAX signals,  it is available to display and manipulate  
large  GEM.IMG files such as produced by a  scanner.   The  extra  
height is used by WEFAX to load all the scan lines in the "large"  
option.   If  you  are  using 1MB the  "large"  option  disallows  
"Rotate" but both are available with 2MB and above.   "Rotate" is  
not available for machines with less than 300KB free. 
  
Chris Strevens, G4ZHT (1993).