Ham Radio 2000 #2/Ham Radio 2000 - Volume 2.iso/HAMV2/FAX_SSTV/VESTER_M/TVINFO.TXT

Text File | 1996-05-13 | 123.1 KB | 3,815 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

                 Copyrights 1993,1994,1995,1996 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  slower  in

     manipulating   the color images (the newer SMARTDRV.EXE  installed  in

     your  AUTOEXEC.BAT as a TSR program makes this much faster) and  won't

     work  at  all on Wefax. Even a floppy drive can be designated  but  it

     will  be ridiculously 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. SMARTDRV, unfortunately, does interfere  with

     the  two  big memory programs that copy data directly to  the  RAM-

     DRIVE,  namely, Wefax and Mode 96 ColorFAX. You can avoid  that  by

     excluding your RAMDRIVE. If, for example your RAMDRIVE is "d" then add

     a modifier to your AUTOEXEC.BAT as:  SMARTDRV.EXE/d:-   to exclude the

     d:  drive.  [In rev. G we have added software  to  disconnect  certain

     classes of TSR programs from the TIME clock while using RT and VT,  so

     you may be able to live with more now.]

          A  new source of troublesome "TSR" programs have shown  up  in

     some  of the newer 486 machines. These are actually "wired in" to  the

     system (in ROM, I presume) and are turned ON or OFF in the CMOS selec-

     tion panel. In particular, the transmit function has been affected  by







     some of these. While the receive program only uses the TIME clock, the

     precision needed for the transmit function was obtained in our earlier

     programs by using the processing speed. Thru Rev. G, we calibrated the

     processor  speed against the TIME clock and then used  the  processing

     speed  as the reference in the actual generation of the transmit  out-

     put. This was susceptible to varying processor speeds due to processor

     cache, etc., so  these functions had to be turned off. When I recently

     got  a Pentium 120 which relied on the burst cache for it's  speed,  I

     felt  compelled to make a transmit program  which only uses  the  TIME

     clock so we could use the high speed cache during SSTV. The  resulting

     transmit  program ended up with no tuning adjustments and  works  well

     across the spectrum from my 286, 386, 486, and Pentium machines.

          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  programs

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

          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.  In

     OPERATTV  we showed how to do this quickly with the batch files;  here

     we'll do it more manually to help you get some BASIC knowledge.  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  inad-







     vertently 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  ques-

     tions.  The program is still loaded, so you only need to hit F2  again

     and  try to follow the instructions this time. If the parameter FI  in

     VU's  SYS CONFIG list (access with F5) is set to FI=1, you will get  a

     complete  list  of  all files in the chosen mode and  you  can  cursor

     select one.

          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 should meet the VESA standard without a driver. In revision H+

     we have added a program (just type C:\TV>vesa to run) which determines

     whether  you already have VESA capability and , if so, reads  out  the

     modes covered and for the modes used what the key parameters, BS,  BL,

     and  BP are. If you have to add a driver, this may also tell you  what

     results when you install the driver (turns out some card manufacturers

     read the VESA standard differently). 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 collec-

     tion 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  opera-

     tion.  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.

          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 MODES.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. To use the full capability of the  Trucolor  (16.7

     million  colors) capability now incorporated into this system,  you

     should go ahead and upgrade to a Trucolor. At revision  D time  you

     can  get  640x480x16.7 million colors in a  Diamond  Speedstar  PRO

     ($100) or Cirrus Logic ($70) boards which are fully VESA compatible

     and available in both VLB and  ISA (to fit the older systems).







          A  couple of people have reported trouble getting  their  VESA

     cards  or drivers to paint a full picture. I ran into this  problem

     myself with a recently acquired Diamond Speedstar Pro which used  a

     Cirrus  Logic video processor chip. We have added a  Bank-Switching

     parameter,  BS, to  the SYSTEM CONFIGURATION which   gives  another

     dimension of control. If the picture paints only part way down  the

     screen,  increase BS. If it goes all the way to the bottom  of  the

     screen and starts re-painting, decrease BS.

          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 case of the Robot 36 mode and the  Colorfax

     high  resolution 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.  The color registration parameters are established, but  have  not







     been  followed  by  all of the new systems, so we put  in  a  variable

     registration  so  you can adjust pictures which are transmitted  by  a

     non-standard system.   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. Type C:\TV>vu and then hit F5 to see  the

     SYSTEM  CONFIGURATION 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; 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  copy-

     ing anomalies 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.

          Note  that the card parameters you have determined for  VU  as

     described  above  will be transferred to most of the  programs  de-







     scribed below.



     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  CON-

     FIGURATION  for  the  program, at the DOS prompt  type   C:\TV>rt  and

     ENTER.  Then  hit F5 twice to view the CONFIGURATION  list.  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 and hit  ENTER.  Then

     type  in and ENTER the values for BS, BP, and BL and 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. Set TC=0 in line 3250 if you only  have

     a  256 color board. After making the selections, move the cursor  into

     the  clear and hit F5 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 (ie, hit F4 which will put SAVE"RT on the screen and

     you just hit ENTER). Some of the other CONFIGURATION items may need to

     be changed later. After SAVEing RT hit F2 to ReRUN and you should  now

     get the picture screen MENU. Key F1 to read the HELP info.

          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. Key up RT  at  the  DOS

     prompt to run the program and select mode 6. 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 superimposed  on

     top of it, you know that the system is copying the incoming signal. If

     nothing  happens  or you get a steady tone without any tick,  the  fax

     audio isn't getting into the serial port. You could have plugged  into

     the  wrong COM port (surprizing how confusing 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  inter-

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

     up  with the pin numbers on the COM port plug. The Wefax  choice  (99)

     will  tick away even if the interface is not connected, so  don't  let

     that  fool you. If the Wefax doesn't tick but gives a  constant  tone,

     you forgot to create the RAMDRIVE and insert it's designation in  line

     3050. You can use "c" for the Ramdrive temporarily to get around this.

     More  recently  there have been some TSR programs  created  which  use

     enough low memory to be incompatible and lock-up the machine. In  Rev.

     K  we have added a measurement in RT of the memory consumed  by  TSR's

     and offer an error message which tells how many TSR memory bytes  need







     to  be  removed. As a last resort, you can remove the TSR's one  at  a

     time  by inserting REM to the beginning of each AUTOEXEC.BAT  line  to

     find  which  one is the offender. Procedure is to use Edit to  make  a

     change  one line at a time, SAVE the result and reboot to try it.  You

     can easily remove the REM's later to reactivate the TSR's.

          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 a rewrite of the image on

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

     ing  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  hit ENTER to select the default 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. Don't overdo this or you  may  get  noise

     speckles  in dark parts of the picture and the VIS (1100 to 1300  cps)

     will be inoperative. When the station announces it will send a certain

     mode, select that mode quickly. 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 6 full seconds  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  (Scot-

     tie, 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 available on the screen). The trans-

     mit 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  transmit 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 past the header.

          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.

          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 six seconds 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.  As  described below in ANOTHER MODE,  we have a VIS  version  of

     this mode now without the long header.

          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 (use F5 to access). If you have a slow  com-

     puter 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.

          The most popular mode on 14230 seems to be Scottie 1, so that  is

     the SSTV mode I chose to use to align the whole machine. After we  set

     the Line Timing for this one mode, all other modes are aligned. PLEASE

     DON'T  ask people to just transmit for your alignment use. Take  what-

     ever  gets sent. [In Rev. G we have added the capability to  align  S1

     while  copying using the lean-right "/" and lean-left "\"  keys.  Read

     OPERATTV.TXT  for  instructions.] Once you determine  what  the  exact

     correction  for S1 mode is the program calculates the  correction  for







     all  the  other modes. The corrections will tend to  scale  with  line

     lengths (ie, the bytes/line).  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. Reports from other users  indi-

     cates  the calculated corrections are usually right on target.  PLEASE

     DO take the trouble to make the S1 pictures exactly square on  receive

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

     you send a picture. If you find you need to trim LT for another  mode,

     LIST  3900-3920  and trim the large number associated with  that  mode

     (ie; LT8 for mode 8, etc.). 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 appre-

     ciate 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.  While most audio recorders aren't stable enough,  using

     the audio channel on a reasonable quality VCR is useful.

          While most people operating on the non-Robot modes have pretty

     accurate  line timing, the Robot modes as mechanized  on  different

     systems  vary all over depending on how many updates  a  particular

     station has. You can use the non-synchronous modes, (11) for Robot  36

     and  (22) for Robot 72, on receive to avoid getting slanted  pictures.

     The  early Pasokon's had different line timing from the Robot  systems

     (on  the  Robot  modes and the Wraase 96), so don't  get  spooked  too

     easily---use  stations  like  N4OBQ or W5ZR  for  accurate  alignment.







     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 CONFIGURATION

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

     the latest LT3 value. The program will only accept values for LT up to

     65,535. You start over with 0  if you need greater numbers.

          After  aligning LT3, 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  mi-

     croinch  (microsecond) off of every  tile. You can slice  several  mi-

     croinches  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". Obviously, 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. We  ran  into

     this in the extreme when we recently bought a 486 laptop. Changing the

     I/O board wasn't a viable option. So we found what was really  causing

     it and added a software fix to hide this hardware problem. This fix is

     included in Rev. G. In revision K we have added even further  immunity

     to this problem. The problem is caused by the I/O board being too slow

     for  the  microprocessor  speed. This incompatibility  was  hidden  by

     adding  slow down code lines in the ROM BIOS, which only helps if  you

     restrict  yourself  to using ROM BIOS. I understand the  later  (EISA)

     systems force compatibility. But with the many 486 systems out  there,

     many  with microprocessor upgrades added (which aggravates  the  speed

     difference),  we  decided to offer a variable delay  correction  which

     could  fit  any case. This IO parameter is in line 3170  of  RT's  SYS

     CONFIG.  Minimum delay of 1 will work in most cases. The symptoms  are

     color flecks in the picture even with strong signals and in an extreme

     case you may even get intermittent operation of the program.

          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  quer-

     ied about screen size take the choice FAX480 PIX (you can only do this

     by setting FI=0 in SYS CONFIG). This gives you the colorizing  choices

     of Wefax described above for viewing IR pixes. Or just VU it as a  B/W

     FAX480 pix.

          Another item on RT.BAS is the parameter, DE, on the SYSTEM CONFIG

     list.  A value around 10 seems to be about right. It is the number  of

     pixel periods after line SYNC is detected before you start copying and

     depends on processor speed. Since the Martin modes have a shorter SYNC

     pulse, DE is less for them. Martin DE's are set in line 857 in RT. You

     must  set DE to numbers less than 256. Generally it will be less  than

     20. I expect you'll be satisfied with the DE choice already made.

          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.

          Since  the above paragraph was written, I  have  added  automatic

     VIS recognition to the program. You need to be within 50 to 100 cps of

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

     VIS frequencies are so close. Unfortunately, people have gotten  care-







     less  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 a small  chance  of  false

     alarm,  so it only works with fairly good  signals. Since I wanted  to

     use  it for unattended operation to copy only fairly noise  free  pic-

     tures,  this fits fine. It's sensitivity vs. false alarm rate  can  be

     changed  by playing with the parameters in lines 2605, 2606,  2607  of

     the RT program. You'll probably end up about where it is now. Rock the

     frequency  around  +  or -100 cps.  to get a feel for  where  the  VIS

     detection  centers.  The TUNE function described below will  tell  you

     exactly what your frequency offset is.

          I  have  made  several versions of the  VIS  recognition  machine

     language  .ASM  module. As of Revision K time, VISCODEE is  the  clear

     choice. I have precisely measured the VIS code frequencies (1200  cps,

     1300  cps  and  1100 cps) being transmitted by  various  stations  and

     except  for the Robot systems, there is considerable variation in  how

     far above and below 1200 cps the systems transmit. One popular  system

     goes  up  to  1300 cps OK but only down to 1180 cps. So  if  you  have

     trouble  with certain stations, record his VIS with an AVT  mode,  and

     look  at the frequencies using the new TUNE program to see what he  is

     transmitting. While absolute frequency measurement is not possible due

     to the vagaries of whether you are on the same frequency, the  differ-

     ential frequency measurement is very precise.

          In  revision I we have added a selectable VIS acquisition   band-

     width,  VW, located in the SYS CONFIGURATION line 3310. Wider B/W  may

     or may not help depending on QRM, since signals over a wider band  may







     tie up the VIS. Something for you to play with.

          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) or d:>tss (Trucolor slidesho) to  view  what

     was  received to decide what to save more permanently. You  can  break

     out of AUTO+SAVE by hitting F5 to goto Basic, or F10 to return to DOS.

     In  revision I we have added an additional feature to this program  so

     it can be used for hand's off viewing. After each picture is saved, it

     is  left on the screen until the VIS picks up a new pix start. If  you

     don't have much RAM for a RAMDRIVE, you can create a temporary storage

     as  c:\tmp to save pix and then dump it later. The DEFAULT choice  for

     F7 pix storage is located in line 2675 of RT if you want to change it.

     To  change a line, call up the program from the DOS line, hit F5  once

     to  get  to  the BASIC screen, then key F1 which types  LIST  for  you

     followed by the line number. After making the change, LIST it again to

     check  it. Then hit F4 (which will type SAVE"RT for you)  followed  by

     ENTER.

          In revision C of RT, we have added the capability when  saving

     pictures  of  doing it not only in full form but also  directly  in

     compressed format using a batch file, PK.BAT, which must be placed  in

     the  same  directory  as SLIDESHO, TRUSHO, etc. In revision D  we  use

     PKZIP  so you need a copy of that. If you like some other  compression

     program,  you can change PK.BAT, PKV.BAT, and PKX.BAT  to  incorporate

     it.

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







     then  LOAD  RT: make a temporary change to RT by hitting F5  and  then

     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. Or you can hit t for the TUNE  program  and

     examine  the  file that way. If you get a message on LT3  while  doing

     this,  just type GOTO 1290 and ENTER to get to the  selection  screen.

     This is another non-obvious use for RT.

          If  you  don't  want the tone  tick  (measures  the  program's

     "heart-beat"),  Rev C has added a "heart" symbol on the  screen  to

     show when the tone is ticking. This is contained in  lines 775  and

     776  in  Rev C in case you want to remove it. The  easiest  way  to

     remove  a  line  but keep it's content for later  reference  is  to

     insert  an apostrophe as the first character in  the  line--turning

     the line into a Comment.

          Since AVT modes have both  a VIS code and a complicated  frame

     SYNC  sequence,  you can get hung up by passing the  VIS  test  but

     missing the frame SYNC test  (it's capture window is narrower than the

     VIS), so when I'm using the F7 mode and the computer is unattended,  I

     just  bypass the frame SYNC and copy AVT's out of SYNC. F7  gives  you

     such  a choice now. 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.



     REVISION D  ADDITIONS TO RT.BAS

          KY1S  added a picture menu screen to his copy of  our  program

     using some fancy Basic programming. It seemed neat, and not expect-

     ing  very many would want to go to that trouble, we decided to  add

     the capability for you to add your own customized picture menu just

     by  making a file. That is, take your own favorite picture and  use

     PCXLABEL   to  add  the  menu  items.  The  menu  pcx   files   are

     MODELIST.PCX,  FCNKEYS.PCX, K3BCSSTV.PCX, and PICKMODE.PCX.  You've

     already seen the one I made. You'll probably want to put your own call

     sign  at  the top. The menu file name, MP$, and it's mode  number,  I,

     goes in line 3240 of the RT SYSTEM CONFIGURATION. Line 3230 gives  you

     a  selection  of menu choices. Try all 3 to see what  the  differences

     are. Also, to minimize the key strokes when operating from the picture

     menu,  we added a small ML program, SELECTMO.ASM, which  gives  single

     key  stroke  mode command (ie. no ENTER required). On modes  like  M2,

     mode  77, which require two key strokes, a 1 second delay  is  allowed

     for the second stroke. This delay can be changed in line 1352 of RT.

          We  have  included the Trucolor viewing into the  RT  program.

     There  are a number of possible choices of picture size  and  color

     resolution  on both the menu screen and the received  pictures,  so

     try  all the combinations to see what you like; lines  3250,  3260,







     and 3270 contains the switches. We have used fractal techniques  to

     take  the pixellization out of the full screen  Trucolor  pictures,

     as described below in TRUSHO.



     REVISION E ADDITIONS TO RT.BAS

          We have added REAL TIME copying capability to RT for those  of

     you with TRUCOLOR video cards and fast enough computers (386-25 mhz

     equivalent  speed approximately). It is switched IN or OUT in  line

     3280  of RT. Robot modes are not covered since they take  too  much

     processing to display quickly. The real time pix is raw as received

     with  no processing or resizing. In fact it gives you a  very  good

     illustration of the effectiveness of our poor man's digital filter-

     ing  which  replaces bytes that lie outside the 1500  to  2300  cps

     range.  In  AUTO modes you'll need to be quick to  catch  the  mode

     names. Also, the six second wait for the AVT header to be  received

     seems  aggravated since you are looking at the screen just waiting.

     Be  sure to get your Trucolor card all integrated using TRUSHO  and

     then  transfer  the card's SYSTEM CONFIG parameters  to  RT  before

     trying this.

          The Wefax mode will also copy in REAL  TIME. While none of the

     real  time screens can be scrolled while copying, the Wefax  has  a

     skip  control to jump the picture to the left on the  screen  approxi-

     mately 1/7 of a screen (less for faster machines) every time you hit S

     (for skip). This actually changes the SYNC point on the incoming data,

     so you'll generally only use it early in the picture. You can  quickly

     see  how far out of SYNC a picture is and estimate how many  times  to

     hit S.

          We have added a TUNE screen to facilitate getting on the other







     guy's frequency and to give you some insight into what the  equiva-

     lent  analog signals look like. It will give you snapshots of  what

     the signal looks like as it comes in (at the expense of  interrupt-

     ing  the copying--the computer is strained to it's  capacity  while

     copying, so interleaving a Tune display without degrading the  copying

     isn't  practical  at the lower clock speeds) or after the  picture  is

     received,  you  can scroll the TUNE screen throughout the pix  to  see

     what's  going on. The same scroll commands used when viewing the  pic-

     ture  are  used.  To view the line SYNC in modes that  have  one,  you

     scroll  down  one line and then hit the left arrow  several  times  to

     bring  the SYNC pulse into view. Now you can scroll down one  line  at

     the time with the down arrow and see successive SYNC's and what  their

     average  frequency is. Or you can scroll along a whole line using  the

     fast  scroll R key. If pix was an AVT copied in AUTO+SAVE, it has  the

     header  captured  and  you can look at the 1600, 1900,  and  2200  cps

     header  patterns.  You  can even go back to old files,  copy  them  to

     d:a.p, change line 880 as described above, and view their tuning. Note

     that the scale on the TUNE screen is not linear.

          When using the TUNE screen while copying, just hit T, and  the

     last  400  or  so pixels are displayed. Hit T again  for  each  new

     snapshot, We used snapshots because displaying continuously is  too

     confusing to use. When you want to resume copying, hit G; or if you

     want to quit, hit Q. The snapshots cannot be scrolled. If you  want

     to look at another stations VIS code frequencies, you can use  mode

     6  and  SPACEBAR to start copying just before the  picture  starts.

     After  copying a few lines, you can halt and go to the TUNE  screen

     to  scroll through his VIS code frequencies which should  be  1900,







     1200,  and then switch between 1100 and 1300. This is probably  the

     quickest  way  to get on frequency. Or if he sends  out  a  tune-up

     tone, the T snapshot in mode 6 would work well.

          If  you have a precision audio oscillator available,  you  can

     calibrate  the TUNE screen more precisely by copying the tone  from

     it.  Calibration for the snapshot is in line 480 and for  the  file

     perusal TUNE screen is in line 2805. The same correction POKE  goes

     in both places.

     REVISION  F ADDITION--We have added REAL TIME copying for  the  256

     color video boards.

     REVISION  H ADDITION--When retransmitting a received pix, you can  now

     retransmit it in a different mode than it was received in--limited  to

     modes that have the same or less resolution than the original.

     REVISION  K  ADDITIONS--It is convenient while discussing a  just  re-

     ceived pix  to be able to quick-save a picture you like without  exit-

     ing  it. You just key F4 and the picture as scrolled at the time  will

     be  saved under the name Q-xxxxx where xxxxx is the number of  seconds

     since  midnight. The storage path is specified in RT's SYS  CONFIG  in

     line  3280. TSS can be used later using "Q-" as a file  constraint  to

     view,  scroll and save permanently those you choose. Then use  command

     C:\TMP>del q-*.*  to dump the temporary files. Also, when discussing a

     just  received  pix, it is convenient to start locating  one  of  your

     pix's in TVT's multipage album without dumping the received pix.  This

     is done by keying F9 while looking at the pix and you will transfer to

     TVT's dual screen mode. More details on this are in OPERATTV.TXT.

          Another  feature  added to revision K is a software  switch,  RC,

     located  in  line 3180 of RT's SYS CONFIG which allows you  to  either

     optimise the resolution or the color fidelity. We chose originally  to







     optimise the color fidelity. Normally the clipper interface is  unbal-

     anced  enough that using highest resolution gives serious  ripples  in

     the color; ie, a constant color will looked mottled and wavy hum  bars

     are  visible.  No matter how bad the interface is, setting  RC=2  will

     completely eliminate this effect--but with a fraction of a pixel  loss

     in  resolution. On HF, the normal multipath disturbance exceeds  this,

     so  it's  not worth trying to improve the interface. On local  VHF  FM

     links, the improved resolution with RC=1 may be useful, however, so we

     made this choice available. You'll have to fool with the interface  to

     get it well balanced. One major unbalance factor is a mismatch in  the

     +12 and -12 vdc in the serial port. My 386 is matched within 0.1  volt

     while  the new Pentium has almost a full 1.0 volt difference  as  does

     the  NEC color notebook. Matched zener diodes with a value lower  than

     the  lower voltage could be added between the IC power  terminals  and

     ground  to correct this type of problem--one guy I know just uses  two

     nine  volt batteries. You could balance out the small  differences  in

     the  halves  of the IC by removing the center-tap  connection  on  the

     secondary  of  the input transformer, and placing a 5 to 10  Kohm  pot

     across  the  transformer  with the pot's center  connection  going  to

     ground. Our TUNE display is ideal for seeing what you are doing  here.

     Just  tune in a CW signal and use mode 6 to copy it. Hit T to see  it,

     330  pixels  at a time. With RC=2 all the pixels will  have  the  same

     value  (unless the signal is FMing). With RC=1, you can see  the  wide

     dispersion  in frequencies between successive pixels and see how  well

     the  balancing lowers this dispersion. Other hams have worked  at  im-

     proving  this  balance to get acceptable color  rendition  on  several

     other SSTV software based systems, so you can get advice from them. As







     far  as I know, no other system offers the direct viewing of the  best

     balance  that our TUNE program does. It also offers a direct  measure-

     ment  of  the lack of fidelity in cycles/sec of  dispersion.  Pictures

     copied  on other systems could be converted into our SSTV  format  and

     direct quantified comparisons made. Using the four pix mode of our TSS

     program, direct comparisons of results can be made. While some subjec-

     tive  comparisons have been made between systems using high S/N  local

     stations, I know of no simultaneously recorded results done using  the

     same  receiver  audio at both high and low S/N conditions  on  several

     computer SSTV systems. Good project for someone out there!





     TRANSMIT PROGRAMS--VT, TVT, and LVT

          The  writeup on previous versions of the software for  these  two

     programs  were  very long with lot's of adjustment  instructions,  and

     fixes  for problems others had experienced. The Rev. H versions  which

     were triggered by a request from KO4VX for computer speaker output and

     by my acquisition of a Pentium with burst cache were shaped to  elimi-

     nate  most  of the previous problems. I believe these  are  compatible

     with a wider variety of computers---time will tell.

          You can do the initial checking of  these program without actual-

     ly 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-tran-

     sistor  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.



     VT.BAS

          In  this program the file to be transmitted is put on the  screen

     to  see if it is the one desired. It stays on the screen after  trans-

     mitting  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 and  Trans-

     mitting  part of this program is accessed using F5 and is copied  from

     RT's SYS CONFIG. Type  C:\TV>vt ,take the default choice for the first

     two  questions, then hit F5 twice to see the SYS CONFIG.  The  parame-

     ters in the CONFIG list is described there, so read the lists now.

          The new transmit program in Revision H puts the output SSTV audio

     on the computer speaker where you can pick it up directly. There is  a

     small  improvement  in jitter by going direct (depending  on  computer

     speed), but at the cost of going into the computer and soldering leads

     to  the  speaker terminals. The speaker leads have +5  volts  on  them

     generally,  so you'll need the original isolation  transformer  (Radio

     Shack 273-1380). I connected the black and green leads to the  speaker

     and  output the white and red leads to the transmitter. You can  still

     use  the  original pin 7 (RTS) output from the serial  port.  This  is

     switched in with parameter OU in line 4160 of the transmit SYS CONFIG.

     Leave it  switched out unless you are using it.

          We  added  a  test mode in earlier versions of  VT.BAS  which  is

     turned  on  by a switch,  TE, in line 2210  in  SYSTEM  CONFIGURATION.







     Switch TE to a 1200 or 1900 cps position and then hook up a counter or

     some  other method of measuring frequency to the output of the  inter-

     face  which normally feeds fax audio to the transmitter. With the  new

     VT this should be right on, so no adjustment is included. If you  want

     to  check  it, load in a Scottie 1 picture, and when you hit  G(o),  a

     prolonged  steady  tone  at the selected frequency  will  precede  the

     picture.



          Another  feature  added to VT.BAS in revision E  is  a  tuning

     reference  tone.  After  loading a picture to  be  transmitted  but

     before keying G to start transmitting, you can key T (for Tone) and

     a  pulsing 1200 cps tone will be transmitted as long as you hold  down

     the  key.  This  is useful for getting everyone  on  frequency  before

     starting picture copying.

          Another  problem  which  I and others have  encountered  is  a

     radical  shift  in frequencies both received  and  transmitted--ie;

     overly  light  or overly dark pictures. This has been  isolated  to

     residual  settings  of computer parameters which are  left  in  the

     computer  after using such programs as JVFAX, HAMCOM,  and  others.

     They  can be removed by re-booting the computer. In Revision  B,  I

     think we have isolated the offending parameters and modified the RT

     and VT programs so it won't be necessary to re-boot. Feedback will  be

     appreciated.

          In  Rev. B, we have reconfigured the headers on both  the  AVT

     modes  and the FAX480 mode. Not having found anyone with  a  FAX480

     receiving  capability  before the original release,  it  never  was

     tested. It had an error in the software. While fixing that, I  also

     brought  out an adjustment so you can tune the initial 244  cps  in







     the  header to  be precisely on frequency. This is located in  line

     3015 of VT.BAS. One more change was made in Rev F. In the AVT head

     ers, while they worked, there was some diversion in the SYNC  point

     depending  on which type of system was doing the  receiving.  Since

     all  the  systems seem to work well with the  headers  from  Bert's

     (W5ZR) AVT pictures, I just scrapped my header generator and made a

     digital  recording  of Bert's header and included it ahead  of  the

     picture.  In retrospect, this would have been a much easier way  to

     generate  all of the headers.

          In  revision D we added the capability to both view and  transmit

     compressed files. You can collect compressed files into a single file,

     but it takes a lot of memory and extra time to extract a single one of

     these  out.  I prefer to collect mine as single  compressed  files  on

     floppies  or in subdirectories named after the mode used; ie, in a  S1

     or M1 or 90 (for AVT90), etc subdirectory. That is, the suffix for the

     uncompressed  files is used for the subdirectory name. Since the  com-

     pressed  files all have the same .ZIP suffix, it is useful to  collect

     them  together  by mode. The VT program can handle  single  compressed

     files; it just takes a little longer for the program to list the  file

     name  and  mode so you know which mode to call up. You  can  use  this

     program  to  view  individual files, however, if you want  to  have  a

     slide-show, it's more convenient to decompress a series of files  into

     the  RAMDISK  or into a temporary directory (I use C:\TMP).  A  simple

     batch  file can be written using wild cards (pkunzip a:*.zip  d:)  for

     this.



     ADDITIONS TO VT.BAS IN REVISION F







          To  save typing time, we have added the ability to select  the

     file name directly from the list of image files using Cursor selec-

     tion.  The  same FI parameter in the SYSTEM CONFIGURATION  list  is

     used to switch this ON or OFF.

          The  "shades  of gray" part of pictures  often  includes  call

     signs.  It could be used for other messages. Some  people  properly

     object  to messing up some really great pictures by  putting  words

     over the picture. So we decided to use the top stripe for contempo-

     raneous  messages. You can store a default message which  might  be

     your  call sign and name and in RT maybe REPLAY-BY-AB4O. When  each

     picture is sent you have an opportunity to insert any contemporane-

     ous message you might want to add. If you type it in CAPS, it will  be

     more readable.



     ADDITIONS TO VT.BAS IN REVISION H

          In addition to the computer speaker output mentioned above,  this

     revision  adds the capability to transmit pictures in different  modes

     than  they were saved in. Only cases which are likely to be used  were

     included,  namely, conversions to modes which have the same  or  lower

     resolutions.  More  details on the conversions are  covered  below  in

     TV2TV.BAS below.



     TVT.BAS and LVT.BAS

          TVT  (Trucolor Viewing before Transmit) was added in  revision  G

     and  is another version of VT which uses the additional  pixel/resolu-

     tion contained in Trucolor boards. Instead of picking files to  trans-

     mit  by name, it displays an album page of 10 reduced size  file  pic-

     tures  at a time across the bottom of the screen. You select a pix  by







     keyboard using 1 to 0 (0=pix 10). A fullsize pix is painted to confirm

     your  choice.  You access it's SYSTEM CONFIGURATION with  F5  and  the

     parameters  are the same as in VT.BAS. Key N(ext) to view the next  10

     pictures  in  the selected directory, etc. If you store  all  of  your

     pixes  in  compressed format you'll need to decompress the  group  you

     intend  to  transmit from before using TVT (decompressing  during  TVT

     would be too slow). I use the RAMDRIVE to hold them, but you can  also

     create  a temporary storage directory, say C:\TMP, and put the  decom-

     pressed files there while operating and then DEL *.* in the TMP direc-

     tory  when you finish. You would then insert C:\TMP\ in line  2120  of

     the  TVT.BAS  SYSTEM CONFIGURATION as the default PATH. TVT  also  in-

     cludes  a file name constraint question which gives another  dimension

     for selection other than directories. For example, if Don had a series

     of  pixes, DON1, DON2, etc., he could select only those by typing  DON

     as  a  constraint. Or you could assign the first letter of  each  file

     name as a category reference (A for art, S for sport, etc.). This same

     category selection could be used when decompressing into the RAMDRIVE;

     ie, C:\TV\S1\pkunzip a*.zip d:  to unzip the art files into d: drive.

          Revision  H adds the ability to transmit pix in a different  mode

     from that which it was saved in, just as in RT and VT.

          Revision K adds a Transmit picture menu to guide you through  the

     picture  selection  and it moves the Transmit mode  selection  to  the

     final step in the process. After you select the mode, it repaints  the

     pix exactly like it will be transmitted in the chosen mode so you  can

     be sure the conversion didn't trim off a significant feature. Also,  a

     dual  RX/TX screen was added to TVT for use when you want to  continue

     viewing  a just received pix while  using TVT to select from the  mul-







     tipage  album the next picture you want to transmit. This  is  entered

     from  RT by keying F9 while looking at the received pix.  OPERATTV.TXT

     has an adequate description of this process. We put in the  capability

     of  selecting  the just received pix so you can  retransmit  it  while

     still viewing it. Also, if someone asks you to retransmit it later and

     you haven't yet overwritten it (it's stored as file a.p which is  used

     as a dummy name for temporary storage) you can call up TVT and hit  F3

     to select it. If you don't get a pix with F3, you've lost it so  imme-

     diately  exit with Q and restart. If you try to make a mode  selection

     after  getting negative results with F3, you're likely to  hangup  the

     machine.  Another change made in this revision involves the  selection

     of headers. I like to use the HD=3 header selection and have a  series

     of picture headers for various holidays, etc. But occasionally I  want

     to  use  the HD=2 billboard header for a contemporaneous  message  and

     it's  inconvenient to go to the SYS CONFIG to change it for  just  one

     pix.  So we added a "bb" choice to the picture header choice  question

     which  will  switch to HD=2 and offer a chance to key  in  an  instant

     message on the next picture chosen.

          An addition beyond Rev. I adds a version of TVT which can be used

     by people without the Trucolor capability. It's called up as LVT  from

     the DOS line. Due to the limited pixel x color capability it uses  the

     full  screen  to display the album of pictures to select from, 9  at  a

     time. After selecting one, it rewrites over the full screen.

          While working on revision K, we bought a NEC Versa V50/C notebook

     with  an active matrix display for a special dump price of  about  1/3

     the  previous price. It had a bad I/O speed problem which I  fixed  as

     described  above in the RT section. Instead of a full  Trucolor  video

     card,  it was limited to 65,536 colors. So we created mods to  all  of







     the trucolor programs (RT, TSS, TVT, etc.) so they will work with this

     card--or  any other card limited to 65536 colors. The parameters  were

     BP=2, BL=1280, and BS=4 (except on the pentium ATI card, BS was = 0).



     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 start back at the beginning when it runs out

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

     program's   associated  batch file, SS.BAT, 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 your programs are not

     in the TV directory, you'll need to change the PATH callout in line 30

     of SLIDESHO.BAS and in SS.BAT. SS.BAT should in any case be placed  in

     a directory which is listed in your path statement in AUTOEXEC.BAT.  I

     find it convenient to store pix files in a compressed .ZIP file (using

     PKZIP)  grouped together by mode. When I want to view them,  I  decom-

     press  the .ZIP file into the RAMDISK (using PKUNZIP---the format  for

     an archived file named S1PIXES.ZIP is: PKUNZIP 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.

          Revision C of the software adds a new capability which is very

     useful if you use the AUTOMATIC + SAVE mode. Typically you store  a

     number of pictures in the RAMDRIVE while the machine is unattended.

     When  you return you use SS (SLIDESHO) or TSS (TRUSHO) to view  the

     pictures in sequence. Often you see ones which you want to save, so

     the capability was added to both scroll, rename, and SAVE in either

     full or compressed formats any picture that you like. When you view

     one  you  like, use the normal scrolls, if needed, and hit  Q.  The

     program  then walks you thru the steps from there. If you  use  the

     compression, it requires the presence of PK.BAT in the same  directory

     where you store SLIDESHO and TRUSHO.

          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.



     TRUSHO.BAS

          This is a version of SLIDESHO that supports TRUE COLOR (ie; 16

     million color) video boards with a 640x480x16.7 million colors mode







     capability.  The display is brighter than is possible with the  256

     color  video board. Also, in Automatic, you can choose between  one

     picture  at  a time filling the whole screen or  4  pictures,  each

     filling  1/4  of the screen but still at full resolution.  You  can

     S(top)  the automatic sequence at any time and restart it  by  hitting

     G(o). I haven't yet found out what video mode number is being used  by

     the different card manufacturers for this mode, so you'll have to  use

     the  VESA choice unless you have the same card I have (Diamond  Speed-

     star  Pro). If you can find out the mode number, it can be poked  into

     memory  location  &H113 with the card driver sequences  in  the  BASIC

     program (the one with your card name on it). Interestingly,  Diamond's

     instruction  manual  said it was mode &H72 but it  actually  was  mode

     &H71.

          In  Rev  C,  we have added capability to  accomodate  the  ATI

     TRUCOLOR  card in  the VESA card choice. I thought the VESA  stand-

     ards  would actually settle on such things as  bytes/line--no  such

     luck! ATI uses the same byte storage sequence as all previous  SVGA

     modes  where  the lines are  stored seamlessly so there is  no  gap

     between  lines. Diamond (or maybe it was Cirrus, whose  chipset  is

     used  in the PRO board) decided to jump to the next 2K boundary  in

     memory at the end of each line. I can't think of any other rational

     choice,  so maybe future cards we see will fit in one of these  two

     categories. The parameter BL is included in the SYSTEM CONFIG  list

     of  each program to set this. If someone comes up with  some  other

     oddball  choice,  just assign the value to BL. The wrong  BL  gives  a

     greatly  slanted picture. Your VESA card's BL can be determined  using

     the enclosed VESA.BAT.







          This  program gives very high quality pictures which can  com-

     pare favorably with any other  SSTV system. The pictures themselves

     are  captured, like the Robot 1200C, at 262,144 colors.  While  our

     basic  program structure could be easily modified to send  and  re-

     ceive  at the full 16.7 million colors, it's  questionable  whether

     you could tell the difference. You can tell the difference  between

     32,768 and 262,144, however.

          Be  sure  to read the section on the Bank-Shift  parameter  in

     VU.BAS  above  when setting the SYSTEM CONFIGURATION  on  this  new

     program. This program, like  SLIDESHO, allows you to save  pictures

     directly.

          In  revision D we  have made a significant improvement in  the

     full  screen pictures. Using fractal techniques, we managed to  get

     rid  of the "square pixel" effect which is characteristic of  lower

     resolution  pictures  which are expanded to fill the  screen.  Line

     2080 has a 3 position switch for choices on the even lower  resolu-

     tion Martin 2 and Scottie 2. Try all  three. I like choice 2 as  it

     has the proper perspective and the pictures are not over-expanded.

          In   revision  F,  we have added a reversed  TRUSHO  which  is

     called TRUS-REV.BAS. Some of the older Trucolor cards have the  red

     and  blue reversed from the current VESA standard, so this  is  for

     folks  with one of these cards. It has been tested with the  Speed-

     star 24X.



     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.  Line 2095 in the SYS CONFIGURATION (use F5) is where  you  make

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

     resulting picture will have the colors scrambled. Change the offset by

     one and try again. In revision I, we have modified this program so  it

     determines the pixels per line and automatically adjusts, so you're no

     longer  constrained to 640x480 TIF files. Provided the software  which

     generated it put the proper header on the file (Alchemy, for  example,

     puts no data in it's TIFF file output header). You can manually insert

     the  pixel's  per line if the file header is  incomplete.  Since  file

     sizes vary but the output desired is usually about 320x240 pixels,  we

     have  two possibilities for TIF file input reduction--one for a  small

     file  around  320 pixels per line  and another for  approximately  640

     pixels  per  line. Parameter SM in line 2097 of  SYS  CONFIG  switches

     between these two. SM=0 reduces the pixel count by two in each axis to

     get an output while SM=1 is a direct one-to-one pixel replication. You

     can  take a 643x482 TIF file, for example, and using SM=1,  create  an

     expanded  picture  of a portion of that file. Try this with  a  "pixel

     offset to center the pix" of 100,000 or so pixels, and you'll see  the

     possibilities. Normally leave SM=0 in TIF's SYS CONFIG since when  you

     are  converting  files from JPG, GIF, etc. with our CONV  program,  it

     uses  TIF as part of the sequence and you can get frustated  when  the







     pictures all come out expanded.

          Different  hams  have found pix manipulation programs to  use  in

     conjunction  with TIF.  WB7PAP found a Graphics Workshop 7.0  on  Rim-

     mer's  BBS (tel:[phone]) which converts other formats very  well.

     It is called GRAFWK70.ZIP. N9ARX reports success using Print Shop  Pro

     for  Windows.W5NOO  likes Paint Shop Pro and Neopaint.  The  shareware

     field  has many such programs. I believe all of these and  other  pro-

     grams accept pictures in many color/pixel 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.[See BATCH  FILES below to see how

     you can take all the work out of conversion and go directly from  from

     GIF, PCX, and JPG files to Transmit.]

          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 using F5.

          Revision  D adds the capability to directly save  any  picture

     generated by this program in either full or compressed formats.



     TV2TIF.BAS AND TV2TV.BAS

          When  writing  a  Wefax article for our Waterway  news  flyer,  I

     needed  to  convert  some hurricane pix I had  copied  using  mode  99

     (Wefax)  and saved in the FAX480 format to a format which N3DKZ  could

     use  directly  in  his Publishing program. I put  together  a  FAX2TIF

     quickie to do this, then decided to expand this to include  conversion

     of  any of the SSTV formats and FAX formats (ie,.FAX and .SVG) into  a

     640x480x16.7 million TIF file. This TIF file is the most common stand-







     ard  for  interprogram transfer and can then be converted to  all  the

     standard formats if desired using a number of programs. It can be used

     in conjunction with TIFCONV to convert from ANY SSTV or FAX format  to

     any other SSTV or FAX format. The default output for TV2TIF is  chosen

     to  match  the default input for TIF (which is the  batch  callup  for

     TIFCONV).

          Since  I wanted to include mode conversion in RT, VT, and TVT,  a

     program  was generated, TV2TV, which goes directly from one SSTV  mode

     to  another  for mode combinations that make sense. This exists  as  a

     stand  alone  program available at the DOS line, and it's  ML  module,

     TV2TFR.ASM is integrated into RT, VT, LVT, and TVT.



     TGACONV.BAS

          I  found a collection of CD-ROM pictures at Dayton which  were

     of  high quality, 24-bit color, but in a TGA format.  This  program

     converts  any 24-bit color TGA file of any line length equal to  or

     greater  than 640 pixels to SSTV files. Using a simple batch  file,

     STGA.BAT,  you can call up any image on the CD-ROM, convert  it  to

     any  SSTV format and then transmit it in a seamless operation.  The

     images  are filed on the CD-ROM as img2018.tga kind of  files.  You

     merely type: C:\TV\>stga 2018 and the picture is transferred to the

     RAMDISK, the TGACONV program is activated, where you pick the  mode

     and  take the default choices. When you see the picture,  you  exit

     with  Q and then F10. The batch program then moves you into the  VT

     program where you answer the questions and transmit. I suggest  you

     study  the STGA.BAT as you can put together  sequential  operations

     using several of the programs. You could eliminate answering  ques-







     tions  even  by making special versions of say  TGACONV  where  the

     question  lines  are  replaced with the answers you  want  for  the

     particular  sequence,  and it will just run straight  through.  The

     special  versions would be given different names, of  course.  Read

     the  DOS book on batch files. You can do some powerful things  with

     a few little lines.[See BATCH FILES below]

          TGACONV also has direct SAVE capability.



     BATCH FILES

          Peter Norton's various books on DOS give good illustrations of

     how  batch files may be used to speed up repeated  computer  opera-

     tions  and you should definitely read one of his treatises.  A  few

     ways  I've used them for SSTV may be useful to you  and/or  suggest

     other uses:

          (1)   Speed up the picture menu paint--If you have  plenty  of

     RAM,  you can copy the menu pix, MODES.M1, to the  RAMDRIVE  during

     the  first use of RT and then have the RT.BAS program load it  from

     there.  That is, change line 3240 of RT.BAS to read (based on  RAM-

     DRIVE of d):

                         3240 MP$="d:MODES.M1"

     The RT batch file, RT.BAT, will then read:

                         copy modes.m1 d:

                         gwbasic rt

          Depending  on how fragmented the memory segments of your  hard

     disk have become, this can be much, much faster.

          (2)  Chain  programs  or portions  of  programs  for  seamless

     throughput from choosing a  file name on a CD-ROM (or stored  else-

     where) to a labelled picture in the transmit buffer  ready to G(o)!







     Examples  of this are described in UPGRADED.TXT, UPGRADEE.TXT,  and

     in  the TGACONV section above. Typically you go from a  batch  file

     DOS  command line into a GWBASIC program which does it's thing  and

     returns  to DOS when it reaches the BASIC command SYSTEM. Then  you

     step to the next line in the batch and continue. Between successive

     programs  you  can  store numbers or data in an  unused  corner  of

     memory  or use the RAMDRIVE to temporarily store images under  some

     common name, like a.p or b.p. Or you can chain back to a batch file

     from within a BASIC program using the SHELL command followed by (in

     quotes) the batch file name and any modifiers. Examples of this  is

     line 442 of VT.BAS and line 1524 in TRUSHO.BAS. Here you return  to

     the BASIC program from the batch file with the command EXIT.  Study

     batch files STGA, PK, TR, and TE for examples.

          Let's  examine TE.BAT in detail (use C:\TV>read te.bat).  This

     allows you to transmit GIF files directly from the DOS line. A file

     named  GEORGE.GIF located in E:\GIF\ would only require  typing  on

     the DOS line--- C:\TV>te george --- and when asked you answer  what

     mode you want to transmit in. TE.BAT reads:

          alchemy -t0 -24 -o -X640 e:\gif\%1.gif d:a.tif

          gwbasic alchconv

          del d:a.tif

          gwbasic alchvt

     This is written for GIF files contained in directory E:\GIF\  which

     happens to be a CD-ROM in my computer. If your GIF files are  else-

     where, put their PATH in place of e:\gif\. The %1 in the first line

     is  where  the batch file inserts the name following the  TE.  This

     particular TE.BAT was written for RAMDRIVE d:. If yours is  designated







     h:, then replace the d in lines 1 and 3 with h. Or, if you don't use a

     RAMDRIVE, just delete the d: and your c: drive will be used.

          Now contrast this with TR.BAT, which is more general purpose, but

     requires you to type out the PATH, FILENAME, and suffix everytime  you

     use it.

          In revision I we have added TG.BAT for transmitting large collec-

     tions  of GIF files grouped in one directory. It includes  file  lists

     from which you can cursor select specific files. Read the TG.BAT for a

     complete explanation of each step. TJ.BAT does the same thing for JPEG

     files and TT.BAT for TGA files (including Pasokon 16 bit TGA).

          Incidentally, ALCHCONV.BAS must have your SYSTEM CONFIGURATION in

     TIFCONV.BAS  transferred to it. Likewise, ALCHVT.BAS gets it's  SYSTEM

     CONFIGURATION from VT.BAS.

          (3) After collecting and saving a batch of pix in the RAMDRIVE

     using  the VIS + SAVE (F7) mode, typically you thumb through  these

     with  TSS (TRUSHO  batch file) and permanently save the  "keepers".

     To  clear out the RAMDRIVE (which happens often here), you use  the

     del *.* command. After inadvertently dumping all the files in my TV

     subdirectory  (TWICE  !  OUCH !), I created a  DLD.BAT  file  which

     safely dumps d: every time. It reads:

               d:          REM switch to d: if not already there

               dir         REM list d: files for final look

               del *.*     REM you still have to answer Y(es) to delete

               c:          REM return to DOS line

     Very simple, but it protects against inadvertent deletions. I keep  it

     in  the  TOOLS subdirectory. The same format could be used  to  safely

     dump a TEMP directory where you might put F7 mode pix temporarily,  or

     where you might unzip particular mode files for TSS or TVT use.







     (4)  I keep VU.BAT  and it's associated files in C:\TOOLS where  it

     can be called up from the RAMDRIVE to view Robot pix not covered by

     SS or TSS.

     (5)  Another  batch, PX.BAT, is kept in C:\TOOLS where  it  can  be

     called   up from any place to PKUNZIP a group of files on a  floppy

     or other location  and deposit them in the RAMDRIVE for viewing--or

     transmitting.  It reads:

                    pkunzip %1:*.* d:

     To unzip and place from drive A into D:, you just type C:\TV>px a .

     (6)  CONV.BAT  is a simple batch for converting PCX, GIF,  JPEG,  TGA,

     etc. files which  Alchemy can handle to any of the SSTV formats.  Just

     type    c:\tv>conv   followed  by the full Path and  Filename  of  the

     desired file. When you are asked for the pixels/line, answer with 640,

     since  that's  what  we've set Alchemy to output. This  uses  the  TIF

     program  exactly  as currently saved, so you may need to  make  SYSTEM

     CONFIGURATION  changes to TIF and SAVE them temporarily. Set OF=0  and

     SM=0 (lines 2095 and 2097) to fit Alchemy output. If you READ CONV.BAT

     you  will notice that the Alchemy command line directs that  the  con-

     verted  picture be forced into a 640x480 shape. If this  distorts  the

     picture,  you can change the 640 in the command line to  maintain  the

     proper perspective for that particular group of pix. Remember the  new

     number as you'll be asked the pixels/line later in CONV operation.

          These  are fairly trivial to compose but greatly improve  your

     operating  efficiency.  Hopefully this will suggest others  to  fit

     your own operating preferences.











     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 TIF file format, in a SSTV format, or in  any  format

     handled  by Alchemy. 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 circu-

     lar 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  SAM-

     PLE2.94  pix.  You can use MODES.M1 as a background  file.  Or  rename

     MODES  with a different mode suffix for a different  background  file,

     etc.  I use the RAMDISK to store successive passes thru  LABEL  (under

     PATH/NAMES of d:a, d:b, d:c, etc.); then with SS (SLIDESHO) or TSS  in

     drive  d: you can view the progressive results. I have  recently  been

     using a shareware program called DAZZLE to get a practically  infinite

     source  of colorful background files. It outputs PCX pix which can  be

     converted using ALCHEMY to TIF and then SSTV formats.

          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. This is accessed using F5 as on other 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 (16 color or 256 color

     files  DO  NOT work!). Put the text in the upper left  corner  of  the

     PAINT screen when you generate the mask. PCXLABEL includes the  direct

     SAVE function in both full and compressed formats.



     3D.BAS

          This is a new program added in  Rev C that creates 3-dimension

     picture  files in our SSTV formats. It is not a synthetic  3D  pro-

     gram,  although  you can get some synthetic depth of  stuff  pasted

     over the picture files with the LABEL program. It uses the original

     "two  camera" approach for 3D. You use your video camera  and  frame

     grabber  to  capture two pictures of a scene, a RIGHT eye  pix  and

     after  moving  the camera a distance about like your  eye  spacing,

     capture a LEFT eye pix. It's hard to keep the pointing angle right,







     so pick some vertical feature in the scene--note where it is in the

     frame  grabber screen w.r.t. the letters below the screen.  On  the

     second pix, adjust the camera pointing to keep the vertical feature

     only a few pixels from where it was on the first pix. The magnitude

     and  direction of this offset can be estimated by closing each  eye

     alternately  and  noting what the apparent shift is from  Right  to

     Left  eye. The final product picture should only show a few pixels  of

     "red  shift"  as seen without the 3d glasses. If  the  glasses'  color

     bandpass  matched  the phosphor colors of your C.R.T., then  the  "red

     shift"  would be of no consequence, since you couldn't see  it.  Until

     color  matched glasses become generally available, assume  the  person

     receiving  your  pix  will not be color matched  and  limit  the  "red

     shift".

          I  store  both of these TIF files in the  RAMDRIVE,  then  use

     TIFCONV  to  obtain two picture files in the  desired  mode,  using

     RIGHT  and LEFT as file names. These feed directly into the  3D.BAS

     program. Use your 3D glasses to see if the result is  satisfactory.

     Slow-scanners  seem enamored of synthetically derived 3D where  you

     take a series of single images and by displacing color frames a few

     pixels  can get discrete depths for the different images used.  You

     can get the same effects using the LABEL programs, but it's labori-

     ous. When you put your call  sign on these 3D pix, you can get  the

     same  effect by pasting the same label on both RIGHT and  LEFT  pix

     but  displaced a few pixels from each other. You can find out  more

     about  this by playing with it. You'll get lots of advice from  the

     synthetic enthusiasts---not all of which is applicable to the clas-

     sic two displaced camera approach which this program is closest to.

          If  you're recording 3D pictures in the field with  your  cam-







     corder, be sure to voice record whether you are in a RIGHT or  LEFT

     eye  position. KB9MC has located a source for 3-D glasses in  Cali-

     fornia; Reel 3-D Enterprises--tel:[phone].



     NEW MODE

          I  considered  adding the Scottie DX mode, but after  studying  it,

     decided it didn't use the extra redundant pixels as efficiently  as

     it might. It basically sends the same pixel value three times in  a

     row  and  then combines these three for a more  noise  free  single

     pixel. This is great for decreasing white noise which is not corre-

     lated  in the three samples. But you only need look at a  few  pic-

     tures  to  see that many of the "noises"  which pollute  our  pixel

     values  (QRM, QRN, multipath, carriers, etc.) are often  correlated

     over 3 successive pixels or more. So I began looking at putting the

     redundancy with time separation between samples--like repeating the

     same  line 3 times in a row. Each pixel would have 3 samples  sepa-

     rated  by one line length in time. The good stability of our  crys-

     tal-locked  receiving   system  would allow us  to  combine  pixels

     separated  in time quite precisely (a system which line  SYNC's  on

     each line using the 1200 cps sync would not combine so precisely!).

     This  would decorrelate the samples against more than  white  noise

     and give better results.

          While  it is generally agreed that there is  more  information

     content in the luminance (B/W) of a picture than in the Chrominance

     (color),  that depends to some extent on a value judgement  between

     spatial  resolution and color content. The engineers would  usually

     opt  for spatial resolution while the artists would probably  value







     color  content.  The more I thought about it, the more  foolish  it

     seemed  to  use completely redundant pixels.  Four  pixels  grouped

     together  in  a square could be exactly the same value and  give  a

     redundancy improvement against noise in preserving that value.  The

     same four pixels could be used to improve the spatial resolution by

     a factor of 2 in each axis, and if conditions were good, you  would

     see  the  resolution improvement. If conditions are bad,  your  eye

     would average those same 4 pixels and get at least as much informa-

     tion  as if they were all sent with the same value. So if  you  are

     going to send more bytes to improve poor condition reception, it  is

     better to use the bytes for better resolution, and let your eyes do

     the  averaging.  Since the signals fade  up and down, you  get  the

     better  resolution when it's up. Also, since most  SSTV  operations

     have  people at different skip distances, some will get  extraordi-

     narily  good high resolution pictures, while the weaker  ones  will

     get  less.  This whole process is illustrated quite well  when  you

     look  at the differences in Martin 1 and Martin 2. Here  the  extra

     resolution is in one axis only, but the difference in results as to

     how  fast  they  deteriorate under worsening  conditions  is  quite

     striking.

          Another  illustration of this is in the FAX480 where the  dou-

     bled resolution in both axes gives very  durable info content under

     quite bad conditions  compared to SSTV modes.

          So  we  decided  to make a full color mode  with  the  doubled

     resolution  in both axes. To avoid start-up problems  with  getting

     everybody  "tuned" to the same line timing, we decided to  use  the

     same  timing as the FAX480. Three successive 546 byte  "lines"  are

     used  for  the Red, Green, and Blue. In fact, it's  nothing  but  a







     double size Scottie or Martin 1 mode--double in both axes.

          It's called mode 96, has a VIS code of &h6A, and uses the same

     LT9 already set for FAX480. In fact you can copy FAX480 pictures in

     this  mode  to  align it (the picture will only  fill  1/3  of  the

     screen). Displaying the extra information in this new mode requires

     a  full 640x480 TRUCOLOR video card---but these are down  to  about

     $70  now (Cirrus ISA boards) and hopefully you have already  bought

     one  to   use TRUSHO in the previous revision. There is  already  a

     large population of hams with the TRUCOLOR cards.

          Some will  question the length of time to send such a picture,

     but  it's  only  a bit longer than the Scottie DX  mode.  Like  the

     Scottie  DX mode, it should only be used sparingly,  and  certainly

     not  often on busy frequencies like 14230. But there are plenty  of

     often unused frequencies on 15 and 10 meters and 75 meters is often

     vacant  during the daylight hours. Also a number of our  users  are

     operating  on VHF bands for local picture trading. When KY1S and  I

     were  evaluating it initially, we shared a frequency with a  strong

     broadcast station on 40 meters, and got surprizingly good  results.

     Even  today we shift  down to Scottie 2 and Martin 2 when the  fre-

     quency  gets busy and go back up when the  conditions  deteriorate.

     This mode is just one more step in that progression. It should be a

     good  match  with the Kodak CD-ROM photo system--and  I'll  make  a

     conversion program choice for Kodak as soon as I can find out their

     format.



     ANOTHER MODE

          We  have  added  a new high resolution  Black  and  White  FAX







     mode---well,  a little bit new. It uses the exact same line  timing

     as  FAX480  and mode 96 Colorfax, and differs only from  FAX480  in

     having  a VIS code attached instead of the lengthy header. We  have

     renamed FAX480 as mode 95, and assigned mode 9 to the B/W FAX.  The

     VIS  code assigned is &HAA (decimal 170). In RT the VIS code   will

     be  recognized  and AUTO operation will be just like all  the  SSTV

     modes. You can still acquire this mode and FAX480 pictures manually

     in RT. In VT  you can choose the VIS-coded mode 9 or use mode 95 to

     put  a  FAX480  header on the picture.  Files  are  interchangeable

     between  these modes and use the same .FAX suffix. When you find  a

     pix which has the detail to justify a mode 96 Colorfax file, make a

     mode 9 B/W fax file so you can send it to folks without Trucolor to

     show  what kind of detail is possible. As described  before,  these

     modes have the 64 gray shades necessary for photo-like quality. The

     resolution is 536x480.



     USER ADDED FEATURES



          If you add features to the programs, which I hope you will,  make

     these adders portable, so they can be easily put into later  revisions

     without  risking overwriting lines by putting them into  line  numbers

     above 6000. Then you can SAVE them as a BASIC ASCII file, and use  the

     MERGE command to add them to any future revision.



     REAL TIME DISPLAY

          Some  have  asked  for real time paint of the  pix  as  it  is

     received. I personally prefer not having it as I use the  receiving

     time  to read the paper, and the incoming pix is  distracting.  But







     many  others  have been used to it. There are tradeoffs.  When  you

     take  the time to paint a line right after it comes in, it adds  to

     the  "edge  of the room" gap we described above (in  RT).  We  have

     chosen to go for maximum resolution (pixels/line) so that  increases

     the gap time over a lower resolution choice. This gap can be hidden

     in  all  but the AVT modes, but only if you copy in SYNC  from  the

     start. We went to considerable trouble to minimize this gap so  you

     can take almost any late start or out of sync picture and scroll it

     into  position with negligible picture degradation. To  our  knowl-

     edge,  no other system offers that capability. Also, we  wanted  to

     accomodate  the  lower speed 286 machines, so the "Store  and  then

     Look"  choice  won the tradeoff. Of  course,  the  state-of-the-art

     moves on, and with such a large population of 486's out there  now,

     we  plan to revisit that tradeoff. Also, the newer  TRUCOLOR  cards

     take  less time to paint a pixel. So if you really want  real-time,

     be  patient. It will only be added, however, if it doesn't  degrade

     the picture quality or the system flexibility. And it clearly  will

     require the faster  computers.

          Revision E adds this feature---and I just can't get my paper read

     anymore!  Can't  resist looking! I have not been able  to  detect  any

     deterioration  with  the interleaving technique used.  It  was  tested

     using  a Pentium 120 as transmitter and a 386-33 receiver and no  dif-

     ference was discernable. At SOME lower speed than 33 mhz it should  be

     significantly different.

     QUAD.BAS

          This  program  is called at the DOS line as QD and  it  offers  a

     quick way to assemble any four files that were saved in the same  SSTV







     format into a four picture "quad" which can either be saved as another

     picture  file or immediately transmitted. It's primary use will be  to

     instantly playback four pictures that were just received. It would  be

     useful for net operation and more efficient than using S2 , for  exam-

     ple.  It allows you to play back groups of pix previously  stored  for

     comparison  by others. Or maybe a medley of pictures of your  favorite

     grandchild, etc.

     HEADERS

          The  original  16 line "shades of gray" header was made  red  and

     green to give some "color" to the initial part of the pix and also  to

     demonstrate  the  smoothness  in color graduations you  get  from  the

     system's  262,144 color capability. Noticing other headers showing  up

     on the air, we decided to add multiple choices. It was extremely  easy

     to  do  with a few pokes. First we added a flat gray  billboard  which

     offers  constant contrast across any messages you might add.  Then  to

     extend the choice to anything you can dream up, we added a pix  header

     choice  to the two most used modes, S1 and M1. The header type  selec-

     tion  is located in the SYS CONFIG lists in LVT and TVT. If  you  pick

     the  pix choice (HD=3), you are offered a chance to pick  a  different

     header on every picture transmitted--or keep the same one by  default.

     The procedure for generating header pix's is a little involved:

     (1)  First,  create  a numbered picture file, say  HDR12.TIF,  in  TIF

     format which is between 610 to 640 pixels wide and 34 pixels down. You

     will  typically take pix with other aspects and stretch them  to  fit.

     This  is standard practice in numerous picture manipulation  programs.

     Now  take the TIF file and using our TIF program convert the  file  to

     two pix in SSTV format, S1HDR12.S1 and M1HDR12.M1. View these with VU,

     SS,  or TSS. Now to get these into an assembly language  module,  type







     the following:

          C:\TV>debug s1hdr12.s1

          -m100 4000 4f00:100

          -q

               When the DOS prompt reappears:

          C:\TV>g

               And the BASIC screen appears. Just type two lines, then:

          def seg=&h4f00

          bsave "s1hdr12.asm",&h100,&h4000

     You  now  have a number 12 pix header stored for use on S1  mode.  The

     same  procedure  is  used  for  a  number  12  header  for  M1,  using

     M1HDR12.M1.  Keep a descriptive list of these to help you  choose  the

     right number. Or you can keep the .S1 and .M1 header files in a little

     separate directory so you can view them later and connect a number  to

     them (ie, exit the pix with Q, choose the SAVE option, but then choose

     defaults  from there on to avoid saving, but in the process, the  file

     name will be typed for you).

          I  have  chosen to eliminate painting the Default  message,  CS$,

     when  using  the  pix header. If you want to keep  it,  eliminate  the

     letters:  CS$="":  in line 4025 of TVT and in line 164 of LVT.



     EXPERIMENTER'S INFO

          To simplify the use and modification of these programs by experi-

     menters, some of the conventions used are detailed here. First of all,

     the  file  bytes are the raw data  as received. If  you  subtract  the

     number 130 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  130

     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-synchronous 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.

          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 put any saved file into any of the VUing programs  (which

     now  include  SAVE) 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. Or you can use the scroll and save functions  in

     SS or TSS to do the same.

          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 (the easiest way  to eliminate them is to put

     an apostrophe before the first word in the line, leaving the  words

     there in case you get another video card at a later date).



     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.  Note

     that the individual core machine language files are copyrighted  so

     they may not be copied and sold as part of any commercial  venture.

     Shareware  vendors may not reproduce these programs.  Also,  copies

     may not be made to ship with any package for which monetary compen-

     sation is charged. Please help me police this!

                                                       Have fun,

                                                       Ben Vester,     K3BC

     5/12/96