DP Tool Club 17/CD_ASCQ_17_101194.iso/vrac/vester_e.zip/UPGRADEA.TXT

Text File | 1994-01-30 | 10KB | 319 lines

                     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: [phone])  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.