Monster Media 1994 #1/monster.zip/monster/HAM/VESTER_A.ZIP/TVINFO.TXT

Text File | 1994-01-30 | 74KB | 2,252 lines

          Please stop right now and make a backup copy of these programs

     on a floppy disk. And activate the Write Protection on that disk !!



                SSTV/FAX480/WEFAX SYSTEM for IBM and CLONES

                       Copyright 1993 Ben Vester



          This system includes a receiving and transmitting program  for

     Amateur  Radio  Color Slow-Scan TV and FAX480 and  a  receive  only

     program for high resolution weatherfax. The so-called SSTV as being

     used  today is really nothing more than color facsimile, so all  of

     these systems are alike in that only one image is transmitted at  a

     time and they all use 1500 hz to 2300 hz as limits for the  modula-

     tion  audio. The system is basically software-based, with the  only

     hardware  required  being  a very simple  audio  clipper  interface

     between  the receiver and the computer's serial COM port. The  com-

     puter  facsimile  input and output to the  amateur  transceiver  is

     transformer isolated to avoid grounding and noise problems. Details

     of the interface are contained in Sept. 1991 "QST" and in Jan. 1994

     "QST".  There was an error in the schematic in the Jan. 1994  arti-

     cle, however. The Transmit audio comes out of the Serial  interface

     on  the  RTS pin, NOT the CTS pin. That is, the  Transmit  coupling

     capacitor  connects to pin 7 on a 9-pin connector, NOT pin  8.  RTS

     comes  out  on pin 4 on a 25-pin connector. An early draft  of  the

     1994 article is contained on this disk under filename,  ARTICLE.TXT

     and should be read for other needed information.



          Doing  all of the fax demodulation in the computer requires  a







     80286 or higher class of computer with higher clock speeds  helping

     the  quality of the images being transmitted and received.  All  of

     the  programs  except  the Wefax program could be  handled  in  the

     minimal  640 Kb. of RAM but to get any reasonable speed in  manipu-

     lating the images after reception a minimum of 1 megabyte of RAM is

     needed.  For  copying Wefax, 4 Mb. is needed for easy  copying  and

     manipulation. 2 Mb. is  almost enough to copy a full pix. A RAMDISK

     should  be created on your computer before trying to run  the  pro-

     grams. Just add a line to your CONFIG.SYS file as follows:



     For 1 Mb. system:    device=c:\dos\ramdrive.sys 368 512 64 /e



     For 4 Mb. system:    device=c:\dos\ramdrive.sys 3072 512 64/e

          If  you must coexist with Windows (uses 2 mb.) 3072  is  2048.

     With  less  memory, you can use batch files  (described  below)  to

     remove Windows from CONFIG.SYS and AUTOEXEC.BAT when you are  using

     SSTV.



     When you reboot the system take note of what letter designation the

     computer  assigns to the RAMDISK as you will need to tell  the  fax

     program  what that is. Now if you only have 640 Kb of RAM  you  can

     use  the hard disk "c" as the designated drive but it will be  very

     slow  in  manipulating  the color images and won't work at  all  on

     Wefax. Even a floppy drive can be designated but it will be ridicu-

     lously  slow.  High resolution color pix's with 3 bytes  per  pixel

     require  a lot of memory, so the old PC's with minimal memory  just

     won't hack it.









          Timing  is extremely critical in decoding the fax  modulation.

     We use the computer's TIME clock and since it is needed   full-time

     during  the actual copying, you may have to sacrifice  other  time-

     related  functions while using  the programs.  Also, since we  need

     both  the TIME clock and most of the memory for our  copying  task,

     the program may not work properly if your system is loaded up  with

     TSR resident programs, particularly ones that use the TIME timer or

     occupy  any  appreciable  memory . This is a  common  problem  with

     programs using SVGA graphics and I notice that my 8 year old grand-

     son  has already learned how to unload the resident  programs  from

     his  computer in order to get his favorite game programs  to  play.

     Some  resident programs may look like small memory users  but  they

     often  use the TIME clock continuosly, so they may  interfere  with

     the  timing functions in the program. This depends on how fast  the

     computer  is. If it's very fast, it may accommodate both  functions

     without interference. For example, with my 33 mhz 80386 computer, I

     can  accommodate  the excellent screen saver,  "BLANK-IT",  without

     interference.  With a slower computer, that might not be  possible.

     When I use my Computer Eyes/RT frame-grabber, however, I even  have

     to remove the screen saver. These resident programs can be  located

     in  your  AUTOEXEC.BAT file for your perusal. The  easiest  way  to

     remove them and add them back is with two batch files,  STARTTV.BAT

     and  STOPTV.BAT.  First, you copy the present AUTOEXEC.BAT  into  a

     AUTOEXEC.REG file. That is:

                         c:>copy autoexec.bat autoexec.reg



     Then you create an AUTOEXEC.TV file that only contains the absolute







     minimum (ie, NO resident programs). The STARTTV.BAT will consist of

     one line:              copy c:\autoexec.tv c:\autoexec.bat

     After  you  run  STARTTV.BAT, you reboot and are ready  to  go.  To

     restore  the  computer to normal, use STOPTV.BAT with  this  single

     line:           copy  c:\ autoexec.reg c:\autoexec.bat

     You,  of  course, could just type the single line  each  time,  but

     using the batch file minimizes your chances of losing your  present

     AUTOEXEC.BAT  file information. If you  have Windows installed  and

     are working with limited RAM, you can add the CONFIG.SYS changes to

     eliminate Windows temporarily to these same START/STOP batch files.

     Once  you  have the system working, you might want to  add  back  a

     screen  saver for use with TV and see if it messes up your  system.

     Another  DOS resident program that is extremely useful to  speed-up

     the  continuous file manipulations in this program is SMARTDRV,  so

     try to squeeze it in.

          The  programs  were developed for use  by  the  experimentally

     inclined radio amateur. It uses GWBASIC to interface with the user,

     so you will need a copy of GWBASIC.EXE (note:some have tried  using

     GWBASIC  that was used on Tandy machines and it did not work.  I've

     used  versions 3.22 and  3.23, both created for true IBM  clones.).

     The guts of the program are contained in machine language  programs

     which are called up by the BASIC program as needed. To  accommodate

     the  wide  variety of modes, the system parameters are  changed  by

     inserting  POKE's in the BASIC program, a different set  of  POKE's

     being  used  for each mode. This allows experimenters with  only  a

     modest  amount of skill in BASIC to create new modes, or  adapt  to

     additional  modes  that others have created. Even if  you  have  no

     previous  experience with BASIC, I recommend you LIST out the  pro-







     grams  and  study them to find how easy it is to make mods.  I  have

     even included some motivations--like getting your own call sign  on

     the pix you transmit, instead of my call sign--to encourage you  to

     learn  a  little  about hexidecimal numbers, about  2  color  image

     formation, and about changing the program.

          To call up the frequently used programs directly from the  DOS

     line you can use simple batch files. For example, to LOAD in GWBAS-

     IC, then LOAD in VU.BAS, and then RUN the program, you can create a

     batch file, VU.BAT, with a single line:

                         gwbasic.exe vu.bas

     Now  you  just  type VU on the DOS line to access  the  program.  A

     number of these batch programs are included on this disk.

          Each  of  the programs has a fairly good description  of  it's

     operation on the opening screen, so you should read both that  data

     and the data below to fill out your understanding. Also each  BASIC

     program is supported by one or several machine language files.  You

     can identify these by looking through the BASIC listing to find the

     BLOAD  command   followed by the name of the .ASM file.  These  ASM

     files must be in the same directory as the BASIC program so it  can

     find them. I recommend you make a separate directory (ie; c:>MD  TV

     and then c:>CD\TV) and copy all the files into that directory.

          In the different programs described below, you are often asked

     to  hit certain keys. The program assumes you are keying the  lower

     case  letter,  so make sure that you don't have the CAPS  LOCK  on!

     They are capitalized in the writeup strictly for  emphasis.



     VU.BAS







          You need to find out how to see pictures on the screen  before

     you can do anything, so we'll start with the viewing program. First

     activate  BASIC;  ie, c:\tv>gwbasic.exe  and then  when  the  BASIC

     screen  comes  up  LOAD"VU.  You actually  hit  F3  and  then  type

     VU---right here is where you can go astray and why you need  backup

     copies.  If  you  inadvertently  hit F4  instead  of  F3  you  will

     SAVE"VU---which  means you will save a blank sheet under the  title

     VU.BAS, writing right over the real VU.BAS program---another reason

     it  helps to use batch programs for normal use. Now hit F2  to  RUN

     the  program.  Read the first screen and then select the  mode  and

     give the file name of the sample picture. Note that the mode suffix

     to  the  filename is added by the program. If you add it  too,  the

     computer  won't be able to find a file with a double suffix, so  it

     will just return you to BASIC (you'll get Ok on the screen when you

     return to BASIC) when you answer all the questions. The program  is

     still  loaded, so you only need to hit F2 again and try  to  follow

     the instructions this time.

          The Video Card is the next selection to be made. If your  card

     doesn't  appear in the first 6 choices, then you'll make  choice  7

     and go find yourself a VESA driver for your card. If it's a  recent

     card  it  may  even meet the VESA standard without  a  driver.  The

     drivers are a product of the board manufacturer and you may already

     have  it  on a Utility disk that came with the card.  I  understand

     that  BBS: [phone] has a collection of drivers if  you  can't

     get  one from the manufacturer. The driver gets loaded  before  the

     program, so you can add it as a first line in the VU.BAT or  RT.BAT

     or AUTOEXEC.TV batch file for convenient operation. Be sure to  try

     all  7 choices before looking for a driver since card  names  don't







     always  reflect  the name of the SVGA microchip used in  it.  Also,

     there are different microchips in the same name boards, so  there's

     no  guarantee  the  most common one I used for  this  program  will

     necessarily  have  the  same software commands.  Some  recent  SVGA

     programs  even include a collection of drivers to select from.  The

     card type is often shown in the first message when you boot up  the

     computer or you can go to the DOS directory and type:

                       C:\DOS>debug                  then type in a dump

                       -dC000:0000

     You may need to hit d again to dump the whole message on the right,

     but  this  will often tell you the origin of the  video  card.  Try

     dumping at D000:0000 and E000:0000 if C000:0000 doesn't work.

          A  more direct way to find out the card parameters is to  call

     the  computer  manufacturer's software assist line. The  card  must

     support  640x480 with 256 colors (requires 512K video  memory)  al-

     though  a  limited  capability is possible  with  640x400x256  (see

     Experimenter's   Info below). Pix SAMPLE.M1 exercises  the  640x480

     capability while SAMPLE2.94 only needs 640x400 so you can use these

     to  explore  your card's parameters. Trident cards with  1  Mb.  of

     video memory are available mail-order for less than $50 so you  can

     easily upgrade.

          When you select the wrong video card, the program will  faith-

     fully  load the picture into the video buffer but no  picture  will

     result.  After  a short wait for the picture loading,  hit  Q  (for

     Quit) and  you should get the BASIC Ok  displayed. Hit F2 to re-RUN

     the program and try the next video card selection. While the  video

     cards  in my two computers are well behaved and don't hang  up  the







     computer  when sent the wrong choice, this may not be true for  all

     cards.

          Once  you get a picture, play with the scroll commands to  see

     what  happens. Moving up and/or left initially will move  the  file

     pointer outside the file and give peculiar results, so move down or

     right  first.  The  arrows work for slow scroll and R  and  L  give

     larger scroll increments (in the special case of the Robot 36 mode,

     the  R stands for Reverse and will reverse the blue and red  colors

     if  you happen to start copying on the wrong line--it  actually  is

     scrolling  but  the  scroll increment is chosen to  be  one  line).

     Scroll through the color frames with R and see what  an out-of-sync

     picture will look like. You can scroll it right back in  sync.  Now

     try the color registration keys, C and X. to see what they do. When

     you  finish, go on to the next program, or maybe at this point  you

     want  to  change the Default choice for the video card to  be  your

     card.  LOAD the program and LIST 2000-3000  to see the SYSTEM  CON-

     FIGURATION  list.  The  first item sets the video  card  choice  to

     either be automatically set to whatever you choose in the next line

     (2030)  or  you can leave it in manual so you answer  the  question

     about  the  card every time you view a picture. The  BR  brightness

     parameter  is like the Color level control on a TV, and it and  the

     TU tuning parameter are only applicable to the Robot modes. Setting

     TU to 1 will give you retune capability in 10 cps increments  which

     allows best resolution in setting the color balance (or hue)  using

     the  F and G keys (note that the F stands for Frequency tuning  and

     the  G stands for Greener). The next  item is the picture  trimming

     parameter,  PT, which you may want to change occasionally.  If  you

     have  a  pix with trash still showing on the right  edge,  you  can







     raise  PT to trim more off the edge. You can change  the  parameter

     and  RUN the program without SAVEing it or you can make the  change

     permanent by SAVEing it. The final item, EX,  allows you to  expand

     the  pictures that have less bytes per line, such as Martin  2  and

     Scottie  2, to fill the screen. This aggravates any copying  anoma-

     lies but gives the more correct perspective for these modes.  Since

     these  modes send only about 1/2 the bytes and use 1/2 the time  of

     Scottie 1 and Martin 1, their fidelity is inherently worse, partic-

     ularly in less than optimum conditions.



     RT.BAS

          This  will be  the most used program, since you will  spend  a

     lot   more  time receiving than anything else. To view  the  SYSTEM

     CONFIGURATION for the program activate BASIC as described above and

     LOAD"RT.  Now LIST (hit F1) 3000-6000. Move the cursor up  to  line

     3030  where  the video card selection is made and type  in  the  VC

     selection  you found worked in VU.BAS. Hit ENTER and then move  the

     cursor back to the bottom of the screen.

          The RAMDISK designation that is stated on the screen when  you

     boot the system will be inserted in line 3050. Most likely it  will

     be "D", unless you have extra disk drives. The COM port you  select

     will  be noted in line 3170. After making the selections, move  the

     cursor into the clear and LIST 3000-6000 to make sure you got  what

     you  wanted.  Note that when you change anything in a line  on  the

     screen,  you must hit ENTER to actually change it in  the  program.

     Also be sure to move the cursor in the clear before hitting any  of

     the  Function  keys. Now SAVE the program as RT.BAS.  Some  of  the







     other CONFIGURATION items may need to be changed later.

          You  are  now ready to check out the interface box  with   the

     program.  Plug in the interface to the selected COM port  and  feed

     audio  from the receiver into it--noise will be OK. Hit F2  to  run

     the program and select mode 6 and ENTER. Normally the program  will

     wait  until it receives a header before it begins to copy.  But  if

     you miss the header, you can bypass that step by hitting  SPACEBAR.

     In this case, with noise or voice audio, you'll need to bypass  the

     header start, so hit SPACEBAR. If you get a tone with a tick super-

     imposed  on  top  of it, you know that the system  is  copying  the

     incoming signal. If nothing happens or you get a steady tone  with-

     out any tick, the fax audio isn't getting into the serial port. You

     could have plugged into  the wrong COM port (surprizing how confus-

     ing COM port numbering is!) or the audio  may not be getting to the

     interface.  You'll  have to reboot the computer if  you  can't  get

     audio  in to start the copying.  (A few people have gotten to  this

     point and got a single interrupted tone and the computer hangs  up.

     This  occurs  when  you try to use a Tandy GWBASIC.)  The  tick  is

     fairly  brisk,   about 2 per second. If it is very slow,  you  have

     some  resident program interfering or you may be trying to run  the

     program  from Windows. Windows slows processing  down  drastically,

     so  the timing-critical   transmit and receive programs  cannot  be

     run  from Windows.  The most common problem with the  interface  is

     wiring  errors. The pin numbers on the opamp seem to get  mixed  up

     with the pin numbers on the COM port plug.

          Once you get the machine ticking, let it run for 30 seconds or

     so  and  then hit H (for Halt) to stop the copying.  The  tone-tick

     should stop and after a brief delay, you should get an image on the







     screen---in this case it will be multi-colored noise. After looking

     at  the image, you hit Q  (for Quit) to exit the image. You can now

     choose  to SAVE the image, retransmit  the image, transmit  another

     file,  or  return to BASIC where you can hit F2 to  setup  to  copy

     another  picture.  The major keys to remember  are  SPACEBAR  which

     bypasses the frame sync and starts the ticking, then H which  halts

     the  ticking and advances you to a picture, and then Q which  exits

     the picture. You should now be ready to copy real pictures.

          Tune to 14230, the most used SSTV frequency and carefully tune

     in the voice of a transmitting SSTV station to make it sound  natu-

     ral. If you have pass band tuning or other methods for shifting the

     received  passband,  move the passband to attenuate the  lows.  The

     lowest  frequency  used is 1100 hz. When the station  announces  it

     will  send  a  certain mode, select that mode  quickly  and  ENTER.

     Different  modes  have different  header lengths---AVT  and  FAX480

     headers  are quite long before they start the picture. The  picture

     copying  should start properly synchronized. On everthing but  AVT,

     this   should be almost immediately after the fax audio begins.  If

     no  ticking starts (give it enough time for the long header on  AVT

     pictures), you missed the header so hit SPACEBAR to bypass. Let the

     copying run until the machine turns itself off (or if you tuned  in

     late  you  may need to Halt when the picture ends).  It  then  will

     display what it copied. The pictures are intentionally offset  just

     a  little to facilitate easy scrolling to position the pix  exactly

     if  you choose to SAVE it or retransmit it. Use the right arrow  to

     drop  the trash off the left edge of the picture and then  use  the

     fine step left arrow to just bring the trash back to the left  edge







     (look  at the right edge to see what you are doing). The  trash  on

     the right will be trimmed off by the VUing program. If it is a  256

     line  picture  (Scottie, Martin, etc.), it will have  16  lines  of

     shades  of gray display so you'll want to scroll down  to see  what

     fell off the bottom of the screen (there are only  240 lines avail-

     able  on the screen). The transmit program adds the 16 line  shades

     of  "gray" display to whatever file it is asked to send, so if  you

     don't  scroll down before saving or retransmitting you'll  transmit

     two  such displays and less picture. (Actually, we use a shades  of

     red  and shades of green display since the gray  looks  incongruous

     with  all the other pretty colors. This was promptly reported as  a

     "fault" by some folks. C'est la vie !). To facilitate scrolling the

     shades of gray out of the picture, the key D (for Down) will scroll

     you down at 8 lines per hit.

          If  the  picture mode was a Robot mode the  three  frames  are

     different  widths  (the  chroma frames are 1/2 the  B/W  frame)  so

     scrolling  affects  the color registration--you scroll to  get  the

     proper color registration. Then you use keys F and G to retune  the

     signal in 10 hz increments to optimise the color balance. The Robot

     modes  are  critical to tuning and deteriorate more  rapidly  under

     poor  conditions so on average don't expect to see  equivalence  to

     Scottie modes.

          When  you SAVE a pix or retransmit it, DO carefully scroll  it

     so the trash on the left edge of the picture is JUST BARELY off the

     left  edge  of  the screen. The transmit program is  based  on  you

     having done that.

          Occasionally,  some  one will send a pix in a  mode  different

     from  what  was announced. Let it go ahead and copy  and  after  it







     shuts  off you can go to BASIC, LOAD VU.BAS and click  through  the

     mode  choices using the d:a.p default file name to find  the  right

     mode.  The picture probably will be skewed slightly, but you  don't

     lose the whole thing.

          Make  a  practice  of listening to the fax  signals  and  soon

     you'll be able to tell what mode it is with the tick rate being the

     most  recognizable  feature.  The AVT's  have  a  very  distinctive

     "triple  chirp" beginning (VIS code repeated 3 times)  with a  pro-

     longed  count down to start and finally the pix starts with a  more

     irregular  sound.  It doesn't appear justified to me  for  the  AVT

     modes to spend so much time on the header. As the number of  people

     using  color fax grows, you can expect some attrition of modes  that

     do not use on-the-air time efficiently. The AVT's don't waste  time

     on line sync's but then they blow it on the header.

          This program was in the development cycle when WB8DQT came out

     with his FAX480. It was easy to add this mode to the software, so I

     did.  He only had 16 shades of gray--my 64 shades processing  gives

     truly  photographic  quality to this mode. Unfortunately,  he  suc-

     cumbed  to the "header syndrome" and loaded up what is a  very  good

     mode with another excessive header (based on unattended  commercial

     fax  machines). I rebelled at this and decided not to make  another

     header  decoder but to just wait until most  of the 20 empty  lines

     in the header were finished to hit SPACEBAR to start it manually  ;

     so that's how you have to manually acquire the FAX480 pictures. The

     empty  lines are readily recognizable by ear. If he had just put  a

     VIS  header  like Scottie on the front end, and  called it  a  high

     resolution B/W SSTV mode, it would have worked great and would have







     been  more welcome on 14230. The obsession with starting "in  sync"

     every  time comes from paper type fax systems. With a  CRT  system,

     the occasional out of sync condition just requires a little scroll-

     ing. Perhaps the next revision will include header recognition  for

     this mode.

          As  I  sit here writing this, it occurs to me that  we  should

     create  another fax standard. We'll use the full screen instead  of

     wasting  room for a few easily remembered key commands, so it  will

     have  640x480 pixels with 64 gray shades per pixel. That will  just

     fit  within the 640 kb. limit in RAM. The header will be  identical

     to the Scottie 1 except the VIS code will be different. Let's  call

     it  FAX640 and we'll assign mode number 96 to it. For the VIS  code

     we'll  also  use 96 (hexidecimal  &H60). The line sync   and  pixel

     rate  will be identical to the FAX480. Since the system pixel  rate

     gives  1024 pixels in 0.5 seconds to match the weather  fax  stand-

     ards,  our  line  timing for 640 pixels will be  0.3125  +  0.00512

     seconds  per  line (data + line sync). It should only  take  a  few

     hours  to add mode  96 to this program and all the supporting  pro-

     grams. Since most pictures from frame grabbers or other sources are

     in  640x480 format, picture reformatting will be simplified.  Maybe

     I'll add the FAX640 mode to the next revision of the software.

          When  you're finished with the picture, hit Q to go back to  a

     selection screen. You can retransmit the picture directly from  the

     d:a.p file where it is stored. Or you can SAVE it.

          You'll be very happy about now if your computer is at least as

     fast as mine, and it's TIME clock loses exactly as many seconds per

     day as mine does. If that is not the case, you will have seen  some

     slant to the sides of  the picture and maybe even some  break-locks







     on  the sync (looks like someone cut the photo and slid the  bottom

     half to the left). The parameters which affect these things are  on

     the SYSTEM CONFIGURATION list (LIST 3000-6000). If you have a  slow

     computer  it may have bad breakup---if that is the case,  start  by

     doubling  the  sync  window (SW). If there  aren't  too  many  sync

     breaks,  ignore them for now and concentrate on adjusting the  line

     timing, LT, first. Since the Navy Wefax is on the air all the  time

     (on  USB on frequencies 3354.9, 8077.9, 10862.9 and 16407.9  Khz.),

     that might be a good choice to set first. Choose mode 99 and answer

     the questions  or accept the default choices. This is the only mode

     that  offers a choice of manual start. If you choose  AUTO-SYNC  in

     this mode as in all other modes you can bypass it by hitting SPACE-

     BAR  if  the SYNC doesn't  show---which happens more often  in  the

     Wefax transmissions. Scroll the image to put some vertical line  in

     the picture against the edge of the screen. If the top leans right,

     lower LT99 and vice versa. You can converge on the right value more

     quickly  if you use a ruler to measure and record  the  out-of-true

     across  the top of the screen for each value of LT you try. If your

     screen  aspect is the same as mine, the formula for the  correction

     is  1125 TAN X, where X is the angle off vertical. Or if you  count

     the pixels you are off by at  the bottom of the screen, the correc-

     tion is about 1125/240 times the pixel offset. That is, measure the

     pixel offset and multiply it by 4.7.

          The  most common mode being used on 14230 seems to be  Scottie

     1,  so that will be a good SSTV mode to align first.  PLEASE  DON'T

     ask  people to just transmit for your alignment use. Take  whatever

     gets  sent. Once you determine what the exact correction  for   one







     mode  is you can calculate the correction for all the other  modes.

     The  corrections  will  tend to scale with line  lengths  (ie,  the

     bytes/line) so you can get very close by taking the correction  for

     one mode and adjusting it for other modes. For example, the Scottie

     1  mode has 878 bytes/line. If we found that it's line timer,  LT3,

     had  to  be  increased  by  25  counts,  then  the  Martin  1  (915

     bytes/line) timer, LT7, would be increased by 915/878 times 25 = 26

     counts.  For  reference  the bytes/line for each  mode  is:  (1)306

     (2)614  (3)878  (4)568 (5)768 (6)960 (7)915 (77)465  (8)745  (9)546

     (99)1024. You may need to do a little more trimming on these calcu-

     lated values for LT. Reports from other users indicates the  calcu-

     lated  corrections are usually right on target, however.  PLEASE  DO

     take the trouble to make the pictures exactly square on receive  as

     any  skew you leave in will be transmitted to the world every  time

     you send a picture. Fortunately, the exact same timing numbers  are

     used  for  transmit, so you can get your  transmit  alignment  done

     without  even  transmitting. Believe me, the people on  14230  will

     appreciate that courtesy.

          I have read a suggestion on one of the BBS that you use a tape

     recorder to copy a picture off the air and then play that back  for

     alignment.  This  will  be a futile exercise unless   you  have  an

     extremely  precise professional recorder (the line SYNC  window  in

     this system is only a few microseconds !). While most people  oper-

     ating on the non-Robot modes have pretty accurate line timing,  the

     Robot systems vary all over depending on how many updates a partic-

     ular  station has. You can use the non-synchronous modes, (11)  for

     Robot 36 and (22) for Robot 72, on receive to avoid having to align

     the Robot LT's but eventually you'll want to retransmit a Robot pix







     and  it  would  be desirable to  have  determined  the  synchronous

     (ie,crystal-locked) alignment---on modes (1) and (2)---with an  up-

     to-date Robot equipped station like W5ZR or N4OBQ. Note that LT1 is

     exactly  1/2 of LT2 so you only need to experimentally  align  one.

     The  calculated  value  for this correction on Robot  will  be  far

     better  than you'll get by trying to align to just any station  you

     happen to hear. I heard a lengthy exercise on 14230 recently  which

     illustrated  how NOT to do this. A station with this  system  asked

     W7--- to send him a Robot picture so he  could align his  LT (which

     is  a no-no). The W7 was using a Pasokon which has  different  line

     timing  from the Robot systems (on the Robot modes and  the  Wraase

     96),  so the frequency was tied up for an extended period  of  time

     aligning  to the wrong standard. Remember the SSTV frequencies  are

     like giant party-line phones with many people listening and waiting

     to  send  or copy pictures. Move your extended chit-chat  to  other

     frequencies.  Since  almost  everyone has  resigned  themselves  to

     copying  Robot  modes using Line-Sync due to the  wide  variety  of

     timings,  the  benefits of crystal locked  reception of  the  Robot

     will  only be available to those who bother to set their timing  to

     the  Robot  standard, and is communicating with a station  who  has

     done the same thing. When making these LT adjustments, note that if

     you  pick anything but the BASIC choice when you exit the  picture,

     you will lose any temporary changes you have made to the CONFIGURA-

     TION list. When you get perfectly square pictures, SAVE the program

     with  the latest LT value. The program will only accept values  for

     LT  up to 65,535. You start over with 0  if you need  greater  num-

     bers.







          After aligning LT, if you still have any sync breaks, you will

     need  to  lower the Gross Timer. The process here is  identical  to

     trying to fit tiles into a fixed size room. We've squared the  room

     with  LT. We have a few hundred tiles  (pixels) to squeeze  into  a

     room  which has a fixed size (LT) and if the tiles are  too   wide,

     the  last tile will  run into the wall  and break sync. The  number

     for GT represents the width of each tile  (pixel). Decreasing it by

     1  will slice one microinch (microsecond) off of every   tile.  You

     can slice several microinches off each tile  (maybe decrease GT  by

     5)  so you're sure it  will fit but that may leave an ugly  gap  at

     the  edge  of the floor. You can cover that over with trim  at  the

     edge  of  the floor, but if you copy the picture  out-of-sync  that

     ugly gap moves into the middle of the floor (picture). So you  want

     to  make GT low enough to eliminate any occasional break  locks  but

     not so low as to leave an ugly gap which will show up when you miss

     sync  on a picture. If your computer is very fast, the  measurement

     accuracy  for  each pixel (tile) will be more precise, so  you  can

     stack the pixels with less gap at the edge without having the  risk

     of  running into the "wall" set by LT. If you have sync  breaklocks

     that  seem  independent  of the GT value, you need  a  larger  Sync

     Window  (SW). The SW represents the amount of time in  microseconds

     it takes the computer to decide if  it's at the LT "wall". Obvious-

     ly, a slower computer needs more time.

          You  may ask why we chose to use only one pixel  (tile)  size,

     GT,  to fit all these different modes (rooms) with  different  line

     timing  (widths).  It  was just a matter of  convenience.  You  can

     further  optimise  the  system by using a  different  GT  for  each

     mode---in fact, with the deterioration you might get from a  slower







     computer, this could be quite worthwhile. You will note that we  did

     use a different GT (GT99) in the Wefax mode.  Remember, the way  to

     see this effect is to copy a picture out-of-sync and look carefully

     at the results at the parting line and on either side of that  line

     look  at the color registration. Since the AVT modes have  no  line

     sync period in which to hide this "gap", the effect is more notice-

     able there.

          People  who have not seen SSTV pictures are usually struck  by

     the  fact that many of them are noisy--in fact, anything  you  hear

     (noise,  splatter, QRM, etc.)will be painted into the  picture.  So

     high S/N ratios are needed for flawless pictures. Narrowing the  BW

     will  help  some, but at some point will smear the  picture  bytes.

     Another  source  of noise was found by KY1S in a  serial  interface

     board  (made by Data Technology Corporation) which he  changed  out

     for  another board he had which was clean. I have heard of  several

     other  cases  since then which were solved the same  way.  Opinions

     have  been heard that this is more common on the newer boards.  The

     effect  varies from a few flecks in the pix to very noisy pix  even

     with  very strong signals. These I/O boards are very cheap ($10  to

     $15) but finding which ones work may take a little research on  the

     air.

          Signal modulation can also come from your receiver. My  TS930S

     is  completely clean while an old ICOM-720 which I use on the  boat

     gives  noticeable hum bars in the pictures even though there is  no

     detectable  hum in the audio. Clearly, the 120 cycle  is  frequency

     modulating  the high frequency phase-lock loop in the IC720 but  it

     was undetectable until I copied SSTV. With such a sensitive way  of







     seeing  it,  I  intend to fix it; and I won't be  surprised  if  it

     improves  my  SSB voice signal. Both of these cases may be  due  to

     design  faults or just to the particular piece of  hardware.  Point

     is, SSTV shows up shortfalls in hardware very clearly!

          You need at least 512 kb. of memory on the video board to copy

     the SSTV modes. The Wefax copying optimally will need 1 mb. But the

     provisions  are  made  in the VUing program to look  at  Wefax  pix

     through  a  640x480  window. The program  provides  1024x768  Wefax

     viewing  on video card choices Trident, Tseng, and VESA  only.  The

     normal Wefax image has 1024 pixels per line and 1536 lines, so  you

     only  see a portion of the total image at a time. The keys  S  (for

     Shrink)  and X (for eXpand) can be used to see more or less on  the

     screen. Also, if you are using the 1024x768 screen, you can get  an

     expanded view of a portion of the pix by switching to 640x480.  Try

     copying  maps in the Wefax mode. You'll be able to read the  really

     small print ! If you want to print a copy of the map, position  the

     place on the map where you'd like the printer to begin to the upper

     left  corner of the screen and hit P to start the printer.  Hitting

     any key will stop the printer.

          The  Wefax images initially appear in 64 gray shades. You  can

     choose  color  palettes 1 through 5 for various  effects.  This  is

     useful for seeing ocean thermal currents like the Gulf stream on IR

     images (you can identify IR images as the black sky will be  white;

     ie,cold). Cold is white and warm is black  in IR images. Or you can

     take  a  vertical profile of the clouds by first hitting G  to  get

     Gray,  then hit C to Color the top (coldest) layer. Each  time  you

     add another C, you color the next lower level. A total of 64 levels

     are  available. This is useful to identify the more severe  weather







     which  generally boils up to higher altitudes. When you use one  of

     the  color palettes, C can also be used to step through  the  color

     palettes  to highlight visibility of small temperature  differences

     at sea level to see things like ocean currents. These currents  are

     of particular interest to fishermen.

          A portion of a Wefax pix may be saved in FAX480 format. You're

     seldom  interested in the whole image and it takes a lot of  memory

     to save the whole thing. I use date/time/mode filenames for  these.

     28MY123V.FAX  denotes  1230Z on May 28 in Visual mode.  Scroll  the

     Wefax image to put the portion to be saved in the upper left corner

     of  the screen (you save 536x480 pixels--I use pencil marks  on  my

     CRT  to  mark these borders). When you or someone you  send  it  to

     views  this  pix with VU, you select the Wefax mode (99)  and  when

     queried  about screen size take the choice FAX480 PIX.  This  gives

     you the colorizing choices of Wefax described above for viewing  IR

     pixes. Or just VU it as a B/W FAX480 pix.

          One  last item on RT.BAS is the parameter, DE, on  the  SYSTEM

     CONFIG  list. I made this delay DE=0 to suit my own practice.  This

     value  starts the picture copying a little early, so you'll  always

     need to hit the right arrow first to scroll  into picture left edge

     coincidence.  You  may  prefer to set it to start  at  the  picture

     beginning--accepting  the risk that QRM will occasionally  make  it

     start  late. If it starts late, you will move the "edge  of  floor"

     gap  into the active picture region instead of hiding it under  the

     SYNC period. You must set DE to numbers less than 256. Generally  it

     will be less than 20.

          When you manually select the mode, the frame SYNC for the non-







     AVT modes is fairly simple and can be spooked  by any 1200 hz  tone

     of adequate length. This has not proved to be a problem except  for

     a very few stations. For some reason, the Robot (?) systems have  a

     capability  to send your call sign in CW at the beginning  (instead

     of  at  the end ?) of picture transmission and they  chose  to  use

     keyed  1200  hz. Most people have turned off this  feature  (giving

     your  call sign verbally, immediately followed by giving it in  CW,

     followed  by  a picture with your call sign on it seems a  tad  too

     often) since it uses valuable on-the-air time unnecessarily. A  few

     gentle reminders may fix this problem. With a little dexterity, you

     can hit the mode ENTER key on the last character of the CW and  get

     a normal start--or just wait until start and bypass with the SPACE-

     BAR for any stations which continue to use this feature.

          Since the above paragraph was written, I  have added automatic

     VIS recognition to the program. You need to be within 50 cps of the

     transmitting  station's frequency for this to work well  since  the

     VIS  frequencies  are so close. Unfortunately, people  have  gotten

     careless  about  being right  on  frequency. When you  select  this

     option, the mode name is displayed as soon as it is recognised. You

     can  break out of this mode by hitting any key, so if it  fails  to

     grab  and  start copying, you can hit the proper mode key  and  hit

     ENTER  twice  to  start manually. This detection is  made  to  have

     almost  a zero chance of false alarm, and it also only  works  with

     fairly  good   signals.  Since I wanted to use  it  for  unattended

     operation to copy only fairly noise free pictures, this fits  fine.

     It's  sensitivity can be changed by playing with the parameters  in

     lines 2605, 2606, 2607 of the RT program.

          I  have made several versions of the VIS  recognition  machine







     language  .ASM module; namely VISCODE.ASM, VISCODEA.ASM and  VISCO-

     DEB.ASM: but have been unable to decide which is best under mistun-

     ing,  QRM, etc. Not wanting to hold up the release of this  version

     of  the software, I have included copies of all 3 so you  can  have

     the  fun of evaluating them. You just type the one you want to  try

     into line 471 of RT.BAS. Any feedback  will be appreciated.

          Another mode added provides Auto-recognition plus Save to give

     you unattended capability. It ignores weak signals. You can  select

     any  drive\path   to  Save the pix in. I use the RAMDISK  so  if  I

     forget it's turned on I won't fill up my hard disk. When I return I

     use  d:>ss (ie, Slidesho) to view what was received to decide  what

     to save more permanently. This program puts itself into an  endless

     loop  so you have to exit it by using CTRL-BREAK. If  it's  waiting

     for  a new picture you may need to also hit another random key.  If

     you  copy (or REName) the desired file in the RAMDISK to d:a.p  you

     can  then  LOAD RT: make a temporary change to RT by typing  a  new

     line  880-----880 GOTO 890----and then RUN the program. Select  the

     mode the picture was copied in and ENTER. The pix will appear as if

     it was just copied and you can rescroll it if needed and then  save

     it permanently. Since AVT modes have both  a VIS code and a compli-

     cated  frame SYNC sequence, you can get hung up by passing the  VIS

     test but missing the frame SYNC test, so I just bypassed the  frame

     SYNC  and copy them out of SYNC. You can eliminate line 724 if  you

     want to keep the frame SYNC. Don't forget to clear out the  RAMDISK

     for  future copying. You can tell when the RAMDISK gets  full  when

     you copy a pix and it only fills part of the screen.

          In my experience with the previous wefax programs, I have only







     seen one computer (a name brand laptop) which didn't have a proper-

     ly  operating crystal-controlled clock. I have heard of one  other.

     The  sympton  is the lines in the pix wander all  over  the  place.

     You'll have to fix the clock to crystal-controlled stability to use

     these  programs  if you run into this. We have seen one  case  like

     this  which only broke out of crystal-lock in Transmit. This was  a

     486  machine  and K3OWX solved it by going out of the  turbo  mode.

     There  is some general trend we have noted that the crystal  clocks

     are not being held to as stringent tolerances as before.



     TX.BAS

          [NOTE:  The TX program has been superceded by the VT.BAS  pro-

     gram below, so it is not being kept updated with new changes. Since

     there  may be someone with a very slow computer who might  want  to

     still use TX instead of VT, it is still included.]

          The  transmit  program  uses  the  same  SYSTEM  CONFIGURATION

     choices  as the receive (RT.BAS) program, so the first step  is  to

     transfer  those  choices.  LIST 1000-2000 to  see  the  choices  on

     TX.BAS. Be sure to put the cursor in the clear and re-LIST to check

     things before SAVEing the modified program. Note that if you  don't

     put the cursor in the clear before hitting a function key, it  will

     type  the function key word right where the cursor is,  over-writing

     the program and giving some weird results.

          Running TX.BAS is very simple. Put  the transmitter in VOX  if

     it  isn't already there. You select the file you want to  send  and

     note  what  mode suffix it has. The mode suffix and file  name  are

     given when the program asks for them and after the file loads,  you

     just  hit  G  to start transmitting. If  you  give  a  non-existing







     path/filename, the program will return you to the BASIC "Ok"  where

     you can hit F2 to try again. In this case ignore the Picture Trans-

     mitted message---it should be obvious that nothing has been  trans-

     mitted. When you key G to start transmitting, the VOX  will come on

     and  the header is transmitted. The tone-tick audio cue will  start

     when  the actual picture starts being transmitted. If you  want  to

     terminate  the sending before the picture is finished, key  H  (for

     Halt).  Listen to the ticks to see that they are very  regular.  If

     you  hear a skip, someone on frequency will probably tell you  that

     the picture had a break-sync. Although it didn't happen on the  two

     computers  I  have, it's conceivable that a different GT  might  be

     needed  for TX.BAS since the overhead processing done on each  line

     is different from the receive program. If that is the case, use the

     lower of the two values for GT in both programs. A better  alterna-

     tive  to lowering GT is available if the offending mode is  NOT  AN

     AVT  MODE. You can LIST 240-370 in the TX.BAS program   and  locate

     the  line that has the data for the offending mode (ie, 290 IF  I=4

     THEN LL=568 etc.etc. is the line for Mode 4). That line will have a

     value  called  out for a parameter SC, which is the number  of  1/2

     cycles of 1200 hz line sync that will be sent on each line.  Lower-

     ing  this value will fix your problem (equivalent to  removing  one

     "tile"). It's very unlikely you'll need to do either. Incidentally,

     don't  try  to send a picture in a mode other than the  one  it  is

     formatted  for. Hopefully I can find time to include a mode  refor-

     matting program in future revisions.

          People seem to be using rather long sub-directory names  these

     days, so if your PATH to the file to be transmitted is long, it may







     not  fit  in the space allocated in the program. You can  copy  the

     file  to  the  RAMDISK as A.P and use the  program  default  choice

     instead if you run into this:ie, if the program rejects a perfectly

     good Path/Filename.

          Before  you  actually start transmitting pictures,  hook  your

     headphones  across the audio transformer output to the  transmitter

     and  listen to the signal while sending a pix. Compare it  to  what

     you hear when receiving. If the frequencies sound quite  different,

     you'll save time by adjusting the header frequency as described  in

     VT.BAS below before proceeding. If the frequencies are very differ-

     ent, you may be breaking out of SYNC on many lines and transmitting

     a mess. We've seen one 486DX2-66 machine  where this was the  case.

     His frequencies were quite low.

          You  can  do  the initial checking of   this  program  without

     actually  transmitting,  of  course. But as soon as  you  do  start

     transmitting,  BE SURE to check that  the transmitter is  operating

     at a low enough level so it won't overheat. Most transmitters  will

     not handle a 100% duty cycle signal  like this and still operate at

     maximum peak power. I failed to take my own advice on this and  had

     to make a multi-transistor repair on my TS-930. If your transmitter

     has an AM mode, set the output power in TV mode to the same  output

     power  level  as AM. This should be plenty safe.  The  audio  level

     resistor,  R_x in the schematic, is set so that you can  leave  the

     transmitter mike gain at the same level whether you are talking  or

     are sending fax.

          A  useful  feature in BASIC is the ability to list  all  files

     contained  in the current default directory. For example,  to  list

     all Scottie 1 files, just type:    FILES"*.S1    and RETURN       .







     TX, VU, and SLIDESHO all can use this, so I have included an insert

     to  make key F9 type the words FILES for convenience. FILES is  the

     BASIC  equivalent  of DIR in DOS format, so the use  of  wildcards,

     etc.  apply.  Note that keys F9 and F10 are not operative  for  our

     program specific-use until at least one program has been RUN.



     VT.BAS

          This  is  identical to the TX program except the  file  to  be

     transmitted  is put on the screen to see if it is the one  desired.

     It  stays on the screen after transmitting so you can discuss  it's

     details.  Q will exit the picture. If you call up a  non-file,  the

     screen   will  be blank---you'll need Q to get back to  BASIC.  The

     SYSTEM CONFIGURATION for the VUing part of this program is seen  by

     LIST  2000-3000 and is copied from VU.BAS. The transmitting  SYSTEM

     CONFIGURATION is seen by LIST 4000-5000 and is copied from RT.BAS.

          I have added a couple of features to this program as a  result

     of  inputs from KY1S. He found it convenient to have listed on  the

     screen  all of the files in the current directory which were  saved

     in  the mode being used every time he picked a mode. That is,  when

     you  pick  mode 3 in the VT program, all Scottie 1 files  would  be

     instantly  listed for you to select  from. With the BASIC   format,

     this is very easy to insert and is a perfect example of how you can

     adapt  to your own operating methods. I thought others  might  like

     this  capability, so I added it so you can switch it ON or  OFF  in

     line 2092.

          Dennis  also  found that his LT numbers had to be  changed  by

     about 400. Other  486 users have also reported a wider variation in







     the  frequency  of the TIME-OF-DAY clock than we had  seen  before.

     While this has a rather small effect on the color registration, the

     headers used  for automatic recognition of modes have somewhat more

     stringent  tolerances. If you get reports of people receiving  your

     pictures  having  to manually start their reception, or you  had  a

     large change in LT or a particularly slow computer, you may want to

     measure  and possibly trim the header frequencies. We have added  a

     test  mode in VT.BAS which is turned on by a switch,  TE,  in  line

     4173  in  SYSTEM  CONFIGURATION. Switch TE to a 1200  or  1900  cps

     position and then hook up a counter or some other method of measur-

     ing  frequency to the output of the interface which normally  feeds

     fax audio to the transmitter. If you use a counter  you will proba-

     bly  need to divide  the signal down by 50 or more to  avoid  over-

     driving the counter. Load in a Scottie 1 picture, and when you  hit

     G(o),  a prolonged steady tone at the selected frequency will  pre-

     cede  the  picture.  Parameter HF in line 4171 can  be  changed  to

     center the frequency. If the frequency is 3% low, raise HF by 3%. A

     potentiometer  to  change the level into the counter is  useful  to

     avoid  the  erroneous results you get by overdriving  the  counter.

     After finding the best value for HF, SAVE it in VT.BAS and put  the

     same value in line 3210 of RT.BAS and SAVE it. While this parameter

     is called "header" frequency, it actually recalibrates both  header

     and picture frequencies with the pokes in line 3011 of VT.BAS  (for

     reference  in case you wanted to change only one of these, 2E9  and

     2EA  are  the location for the header and 1FE and 1FF are  for  the

     picture  data frequency). Many SSTV stations can give you  a  rough

     measurement of these frequencies over the air.









     SLIDESHO.BAS

          SLIDESHO  works just like VU except that it has an  additional

     capability  to  step through a series of pictures  without  knowing

     what  the  filenames  are. You pick a mode, and if  you  want  some

     constraints in the filenames viewed, enter that. For example, if you

     wanted  to look at only Scottie 1 pix's starting  with the  letters

     BE, enter 3 for the mode and enter BE for the constraint. The first

     BE*.S1 pix in the directory will paint. To see the next BE*.S1 pix,

     hit N (for Next). It will exit to BASIC when it runs out of  files.

     You can use this program to look at single files also. This program

     (and it's associated files, SS.BAT and 64SHO.ASM) is configured  to

     go into your DOS directory, so it will be accessible from any drive

     or any directory where you might have picture files. If you want it

     somewhere  else, you'll need to change the PATH callout in line  30

     of  SLIDESHO.BAS and in SS.BAT. I find it convenient to  store  pix

     files  in a compressed .ARC file (using PKARC) grouped together  by

     mode. When I want to view them, I decompress the .ARC file into the

     RAMDISK  (using  PKXARC---the  format for an  archived  file  named

     S1PIXES.ARC  is: PKXARC S1PIXES d:). After the files load,  with  a

     quick d:>ss I can start the show. Incidentally, this program is not

     configured to work with the Robot modes or the Wefax mode.

          Another  feature  added  since the original  release  is   the

     capability to make the SLIDES advance automatically. The number  of

     seconds  you want to dwell on each slide can be set in SYSTEM  CON-

     FIGURATION, line 2050 as DL. Instead of N(ext), you key A(utomatic)

     to  start the show. It will go through every pix in  the  directory

     and  then start  over again indefinitely. Q will exit sequence.  If







     you get large numbers of pix in the same mode in one directory, you

     may  have  to raise the "files=" reservation in CONFIG.SYS  to  use

     AUTO mode.

          When you're all finished remember to clear out the RAMDISK  if

     you  used  it for temporary storage and you're going to  return  to

     copying  pictures; particularly Wefax which uses a lot  of  RAMDISK

     memory.



     TIFCONV.BAS

          If  you  want to create some picture files to  transmit,  this

     program will convert from the TIFF 640x480, 24 bit color format  to

     the SSTV/FAX480 formats. We chose the TIFF format because it is the

     most  common  format used for  transferring  high  color/resolution

     pictures  between  programs and is an available  format  from  most

     frame  grabbers. The typical frame grabber will accept images  from

     any video source. I have tried this with both the Computer  Eyes/RT

     and  S.S.C.  grabbers.  For some reason,  the  picture  information

     started  at a different offset into the picture file in  these  two

     cases.  LIST  205 in this program will show you where to  make  the

     change  for this. You'll know when the offset is wrong as  the  re-

     sulting  picture will have the colors scrambled. Change the  offset

     by  one and try again. Note that the TIF file must be 640x480  with

     24-bit color so the  file size is over 920,000 bytes. If it doesn't

     have  that many bytes, it isn't an acceptable format. KY1S  reports

     that  he  has used TIFCONV with the TEMPRA program and  with  PHOTO

     FINISH  3.  WB7PAP found a Graphics Workshop 7.0  on  Rimmer's  BBS

     (tel:[phone])  which converts other formats very well.  It  is

     called GRAFWK70.ZIP. N9ARX reports success using Print Shop Pro for







     Windows.  The  last two are shareware. I believe all  of  these  and

     other  programs accept pictures in lower resolution  formats  which

     can then be converted to the highest resolution format that we use.

     The TIF file must be in a non-compressed format. I use the  RAMDISK

     as temporary storage for this monster file and immediately  convert

     it to a SSTV format for permanent storage.

          Since this program includes the VU program to show you the end

     result,  you must transfer the SYSTEM CONFIGURATION from VU.BAS  to

     lines 2000-3000 in this program.



     TIFLABEL.BAS and PCXLABEL.BAS

          You may have one of the fancier software programs to take  the

     original  TIFF  file and add text titles and labels  to  it  before

     converting  it to the SSTV format. I don't, so a LABEL program  was

     written to give some limited capability in this area. Not having  a

     library of fonts and of different background patterns to paint  the

     letters with, we made the program general purpose enough to use any

     font and any background pattern you can take a camcorder picture of

     or can obtain in a TIFF file format or in a SSTV format. There  are

     a number of interesting patterns right in the room you are  sitting

     in which will add interest to your labels---wicker chair back, tile

     floor,  rug, venetian blinds, etc., etc. These two  program  accept

     TIF or PCX 1 bit (ie, two  color) files which might typically  come

     from  a handscanner or one of the many PAINT programs  of  whatever

     font  letters you may choose. Typically you can resize the  letters

     to  fit. The TIF or PCX file  is used as a mask and where ever  the

     file  picture  is black, the LABEL program inserts either  a  color







     which you can choose, or a cutout from any background file  picture

     which  you might have available. You can even use a pix you  copied

     on  the air as a background file. The effect is as if you  cut  the

     letters  out  of the background photograph and pasted  it  on  your

     picture.  You manually select where you paste it on. You can get  a

     three dimension effect by pasting on a color mask, then going  back

     through  LABEL  again, moving the mask a few   pixels  and  pasting

     another  color  or  background file on top of  what's  there.  With

     multiple  passes,  you can get a variety of effects. You  also  can

     make  a square or circular mask and place it to transfer a face  or

     some  other  feature of one file to paste it over another.  A  mask

     file, K3BC.PCX which is 64 pixels wide, is included for you to  try

     out this program on the SAMPLE.M1 pix. You can use SAMPLE2.94 as  a

     background file. Or rename SAMPLE2 with a different mode suffix for

     a  different background file, etc. I use the RAMDISK to store  suc-

     cessive  passes  thru  LABEL (under PATH/NAMES of  d:a,  d:b,  d:c,

     etc.);  then with SS (SLIDESHO) in drive d: you can view  the  pro-

     gressive results.

          Since  these programs use VU for VUing, you must transfer  the

     SYSTEM CONFIGURATION you settled on in VU.BAS to lines 2000-3000 in

     these  programs.  Some TIF 2-color files don't seem  to  work  with

     these,  but  I have not found a PCX 2-color file  source  yet  that

     doesn't  work. Put the text in the upper left corner of  the  PAINT

     screen when you generate the mask.



     EXPERIMENTER'S INFO

          To  simplify  the use and modification of  these  programs  by

     experimeters, some of the conventions used are detailed here. First







     of  all, the file bytes are the raw data  as received. If you  sub-

     tract the number 138 from each of them and XOR the result with  63,

     you  will  get the actual color amplitude for that byte  in  6  bit

     format. Conversely, you can take a picture in 3x6=18 bit format and

     convert each of it's bytes  to the SSTV format by XORing each  byte

     with 63 and adding 138 to the result.

          The  symbol,  LL,  refers to total line  length  (measured  in

     bytes/line) in a picture. This includes sync bytes, picture  bytes,

     etc.

          The symbol L refers to the byte count in a single color  frame

     line. This also is the number of pixels in the color picture. Since

     there  are  3 colors, 3xL would equal to the line  length,  LL,  if

     there were no sync bytes. In the AVT modes, there is no line  sync,

     so there 3xL=LL.

          The  symbol  I is the mode chosen. Or in one  case  where  two

     modes are used in a program, J is used for the second mode.

          The symbol FS is used for frame sync. If this is called out in

     a mode, then a routine is inserted which holds the program  captive

     until  a 1200 hz sync is received before it allows the frame to  be

     copied.  Parameter  DE allows you to adjust the delay  after  frame

     sync before the picture copying begins.

          LT denotes line timing with LT3 being line timing for mode 3.

          D% represents the number of lines in the picture mode.

          DR$ is the letter assigned to the RAMDISK (with quotes, "d").

          SW   is the line sync  window in TIME clock  counts  (approxi-

     mately in microseconds).

          EA  is  the number of bytes used by the line sync when  it  is







     present.  In  the viewing program, this same number is  POKEd  into

     memory  location,  &H3EA, which is where it got it's name.  In  the

     transmit  program it is the bytes thrown away in each line  of  the

     file being transmitted and replaced by sync. It is identical to the

     above except in the non-synchronously copy modes , (11) and (22).

          VC is the video card choice.

          S%  is  the number of bytes a picture was scrolled to  get  it

     aligned  for SAVEing. It is returned as an output when you run  the

     VUing  program.  It  gets converted to it's 4 byte form  as  S!  in

     RT.BAS.

          SC  is used in the transmit program and represents the  number

     of 1/2 cycles of the sync frequency (1200 hz) transmitted  on  each

     line.

          LI  is  used  as the number of picture lines  in  the  TIFCONV

     program. This program also uses Z as the byte value to be  inserted

     in blank bytes. Z=138 is white; Z=249 is black.

          The  files as SAVEd have the picture color bytes placed  in  3

     successive groups of bytes, each group being L bytes long. Then the

     line  sync  bytes (if they are used in the  particular   mode)  are

     tacked on to the end of each line.

          The  DEF  SEG statement in each of these  programs  tells  the

     program  where in memory to place the program. All of the  programs

     are  relocatable,  so  if you find interference  between  some  TSR

     resident program and one of these programs, you may be able to move

     it  up to keep from overwriting the  TSR (typically, this shows  up

     as a computer hang-up which can only be cleared by re-booting). You

     still need enough memory between DEF SEG and &HA000:0000 to  accom-

     modate the pictures you want to copy.







          If  you  find all  of your Robot pictures  are  initially  too

     green or too purple, you can change the number 10 in line 1371  (in

     both  memory  locations)  of RT.BAS to better center  it  for  your

     particular tuning habits.

          If you find that you want to reset the default setting for the

     color  registration  on a mode, you can find out what  the  desired

     values  are  by first using C and X to get what you like  with  the

     VU.BAS  program.  Then when you return to BASIC,  type  PRINT  PEEK

     (&H3EA).  This  will be the new value to poke into &H3EA  for  this

     mode.  Then  PRINT  PEEK(&h15D) and call the value  A.  Then  PRINT

     PEEK(&H15E) and call the value B. Then PRINT PT. The new value  for

     L, the color frame width, then is L = A + 256*B + PT. These  values

     are added back into the program and SAVE'ed. This capability is not

     available in the Robot modes.

          The  color  shades display at the beginning of  the  256  line

     modes  has my call sign (K3BC) superimposed over it. In  order  for

     you  to  change it to your call sign, you'll need to  learn  a  bit

     about how two-color (or 1 bit) images are formed. If, for  example,

     in  the  call sign array of bytes you wanted to make  the  first  8

     pixels overwrite white, you would make the first byte equal to  255

     or in hexidecimal, &hFF (which is 1111,1111 in binary). To paint the

     first  4 pixels out of 8, the first byte would be &hF0  (in  binary

     equals 1111,0000). Look at the lines starting at 780 in the  TX.BAS

     program,  at  line 3430 in VT.BAS, and at line 2400 in  the  RT.BAS

     program to see how to figure out what DATA bytes  to include to get

     your  call sign. Once you determine the DATA array for  your   call

     sign  insert it in all three programs. If you have 6 characters  in







     your call sign it'll be a bit crowded---time for an upgrade!  Don't

     try  to  change  the number of DATA bytes. If you're  too  lazy  to

     figure  this out, you can signal that to the world by changing  all

     the DATA line bytes to 0, which removes the call sign.

          If  you  belatedly decide to save a picture  and  haven't  yet

     overwritten it in D:a.p then you can recover by LOAD "RT" and  then

     typing  a temporary line---- 880 GOTO 890. Now execute the  program

     choosing  the same mode as was used to capture d:a.p.  The  picture

     will  show up and you can scroll it to the proper position and SAVE

     it. You can move any file to d:a.p and re-scroll it this way if you

     don't like the initial choice you made when you saved the file.  Or

     if you want to transfer a part of one file to another using  LABEL,

     use this method to scroll the transfer image to where you want  it,

     and use the new file as a background file.

          In  the  transmit program, each mode has it's VIS  code  poked

     into memory location  &h3A5. The delay (in pixels) between the  end

     of  the VIS code and the beginning of the red frame is  poked  into

     memory  locations  &h523  (LSB)  and &h510  (MSB).  This  delay  is

     switched in by the poke, poke &h52B,227, and is used in S1, S2, and

     WR96. The pokes into &h373, &h374, and  &h375 are to switch a  path

     inside  the  program for modes which have the 16  line  gray  shade

     header.

          A  few  of  you  may have a  SVGA  card  which  only  supports

     640x400x256. You can still view up to 200 lines of picture, but the

     perspective stretches the picture vertically by a factor of 480/400

     in the 240 and 256 line modes. The programs are constructed to  use

     the 640x400 mode for the AVT94 (mode 6) only. There are a number of

     lines  which  state:   IF I=6 THEN POKE &h113 or  &H398  with  some







     number.  If  you take these lines and eliminate the  "IF  I=6"  con-

     straint  you will use the 640x400 for all modes:  specifically  you

     delete the words "IF I=6 THEN"  in each line and leave the POKE. In

     the RT.BAS program, the lines affected are 1765, 1815, 1875,  1925,

     1995,   and   2045.  In  the  VU.BAS,  VT.BAS,   TIFCONV.BAS,   and

     SLIDESHO.BAS  programs  the affected lines are  1590,  1635,  1685,

     1735,  1787, and 1835. In PCXLABEL.BAS and TIFLABEL.BAS  the  lines

     affected  are  1540,  1610, 1680, 1740, 1820,  and  1890.  Strictly

     speaking, you only need to eliminate the constraint for the partic-

     ular  Video Card choice you are using. To my surprise,  a few  sys-

     tems have shown up with 640x480 but not 640x400. If you have  this,

     just  eliminate all of the above lines, and mode 6 will be  painted

     in the 640x480 screen.



     COPYRIGHT NOTICE

          These programs were developed for the free use of other  Radio

     Amateurs  but  since they might have other commercial use,  I  have

     registered them with the U.S. Copyright Office. Radio Amateurs  are

     free to make copies for other amateurs provided no monetary compen-

     sation  is involved. Any other use for commercial purposes is  for-

     bidden without specific written permission from the author.  Share-

     ware vendors may not reproduce them.

                                                       Have fun,

                                                       Ben Vester,    K3BC

     1/30/94