


                     UPGRADES TO SSTV/FAX480/WEFAX SYSTEM



               We have added a number of improvements to the  soft-

          ware-based  system  described  in reference  1.  A  brief 

          outline  follows with a much more  extensive  description 

          being included in the instruction manual which is includ-

          ed in the new software.

               (1) Since the Wefax pictures take up a lot of memory 

          space  to store the whole thing, we have added the  capa-

          bility  to save a portion of the image in FAX480  format. 

          This  gives  a  "blow-up" of the area  of  interest,  and 

          provides another source of FAX480 files. Figure 1 shows a 

          visual mode sample of this. Get out your magnifying glass 

          and look at the surprizing amount of ground detail avail-

          able  in these HF images when you have 64 shade  process-

          ing. If the recipient of the image has our system, he can 

          colorize the IR images to see cloud tops, ocean currents, 

          etc.

               (2) Automatic recognition of the VIS codes has  been 

          added  as a mode in the receive program.  The  recognized 

          mode is printed out and the machine continues to copy  in 

          that mode. Manual choice of a mode is available while  in 

          Automatic if the VIS header got QRM'ed out.

               (3) Another automatic mode is identical to (2) above 

          except  it has an automatic SAVE added for every  picture 

          copied,  with the file names being sequential letters  of 

          the  alphabet. I use the Ramdisk as the  recipient  store 

          for  these  files while in unattended operation,  as  I'm 







          afraid  I'll  forget it's turned on and fill up  my  hard 

          disk.  The  VIS  recognition doesn't pick  up  very  weak 

          signals, so most of the images stored are not too noisy.

               (4)  We  added  an Automatic mode  to  the  SLIDESHO 

          program. You set the dwell time you want for each  slide, 

          and  when running, just hit A(uto) to start a  continuous 

          sequence of all the current directory files in the  cate-

          gory  chosen. The slide sequence  continues  indefinitely 

          until you halt it. 

               (5) KY1S added a feature to his copy of the transmit 

          program  (actually the View and Transmit program, VT.BAS) 

          that  automatically  provides a listing of all  the  file 

          names  in  the  current directory which  match  the  mode 

          chosen  (ie,Scottie 1, etc.) after you  activate  VT.BAS. 

          You  pick  a file picture from this selection and  it  is 

          displayed  for you to be sure it is the one you   wanted. 

          This  only took a few BASIC commands to implement,  so  I 

          added  it. Since not everyone might want this feature,  a 

          switch  is provided in the CONFIGURATION list to turn  it 

          on  or off. Dennis has provided a perfect example of  how  

          you  can  adapt the program to your own  operating  style 

          using the BASIC format.

               (6) Since we found that 2-color files for the  LABEL 

          program  were more available from the multitude of  Paint 

          programs in a PCX format, we added a PCXLABEL program.

               (7)  Some people objected to the "tone  tick"  audio 

          cue  but were not satisfied with the loss of  information  







          when  they turned it off with the program switch. I  find 

          this  invaluable as a measure of the "heart-beat" of  the 

          system. Since some computers have a fairly loud  speaker, 

          you  can  combat  the noise by inserting  a  resistor  in 

          series with the speaker lead to reduce the volume.  Some-

          what  reluctantly, I have added a visual screen cue  that 

          will  light when the machine is ticking if you must  turn 

          off the speaker (lines 485-487 in RT.BAS).

               (8) Since the program uses 262,144 color  processing 

          and display, picture sources must support the high  color 

          resolution.  Some  had difficulty  finding  image  format 

          manipulation  programs which offered an output in  24-bit 

          TIFF  format  to match my TIFCONV  program.  Listing  the 

          people  who  have found solutions to this:  KY1S  reports 

          using  Tempra  and Photo-Finish 3;  N9ARX  reports  using 

          Paint Shop Pro For Windows;  WB7PAP reports using  Graph-

          ics Workshop 7.0 (he found this on the same Steve  Rimmer 

          BBS listed in reference 1 as a source for video  drivers: 

          416-729-4609).  The last two of these are shareware  pro-

          grams.  These programs accept different color  resolution 

          files in GIF, PCX, etc. formats. The final SSTV files, of 

          course, have no more resolution than the source files.

               (9)  One  unexpected result that has arisen  as  the 

          system has been tried on a larger number of systems is  a 

          much wider dispersion of Time-of-Day clock frequencies in 

          many  of the newer systems (mostly 486 systems). I  chose 

          this source of system timing specifically because it  was 

          generally  held to close tolerances. Since the Time  gets 







          updated  from the battery-operated clock every  time  the 

          computer reboots, this tolerance apparently was let slide 

          due  to  competitive pressures. The line  timing  adjust-

          ments,  LT,  in some cases required a  larger  correction 

          than  expected, but most people handled that  well.  They 

          report  that  you  only need determine  one  mode's  line  

          timing  experimentally, and all the others come right  on 

          using the LT formula. I have added another simple formula 

          which makes the initial correction possible after copying 

          only  one picture to ease the work if you have  a  system 

          which diverges from the mean significantly.

               A  somewhat more serious problem has arisen in  some 

          of these systems, as the wider variation in frequency has 

          moved  the  transmit header frequencies  (ie,  the  Frame 

          Sync) far enough to exceed the acquisition window of most 

          systems  with  automatic  VIS recognition.  This  can  be 

          adjusted  out  with a few judicious Pokes. To  make  this 

          easy  we  have added a 3 position switch  to  the  SYSTEM 

          CONFIGURATION  in  VT.BAS  which allows you  to  put  the 

          system  in  a Test mode so as to measure and  adjust  the 

          header  frequencies  directly. In one extreme  case,  the 

          frequencies  were far enough to break out of  SYNC.  This 

          adjustment  should take care of such situations and  also 

          satisfy those who want their signals "right on"  frequen-

          cy.

               (10) Some of my sailing friends who use laptops with 

          only 16 gray shades displays wanted the improved process-







          ing on Wefax incorporated into those programs. Also  some 

          Wefax users prefer the 16 shade format since it uses only  

          1/2  the memory for storage. A collection of  these  pro-

          grams  including automatic scheduling for maps  has  been 

          included  for  those folks and others who  only  have  16 

          color display capability.

               (11)  Another  problem which has shown up in  a  few 

          cases  is noisy I/O cards. This shows up as noise in  the 

          picture even with very strong signals. KY1S reported this 

          first  and fixed it by replacing the offending card  with 

          an  older type he had around. Others have used  the  same 

          fix. I have no significant data on which brand cards  are  

          faulty  and more importantly which ones aren't. If  those  

          who have encountered this problem and solved it will send 

          me the information, I will include it in later  revisions 

          of the software for others to use. These cards are  cheap 

          ($10 to $15) so replacement shouldn't be burdensome.

               (12)  Other information gleaned from helping  others 

          get the system working is included in the new instruction 

          manual, TVINFO.TXT.

               The  above additions are included in a  new  release 

          available  on  the ARRL BBS (tel: 203-666-0578)  as  file 

          VESTER-A.ZIP. By the time this gets published, the  revi-

          sion may be beyond -A.



                                             Ben Vester, K3BC

                                             4921 Bonnie Branch Road

                                             Ellicott City, MD 21043







          

          Reference:

          (1)B.  Vester,  "An Inexpensive SSTV  System",  QST,  Jan 

          1994, pp 27-29.     


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