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World of Ham Radio 1997
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Text File
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1997-02-01
|
15KB
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377 lines
SLOW SCAN TV
using the
SOUND BLASTER
Required equipment:
IBM (or compatible) computer, the faster, the better!
Math co-processor not necessary, but also is nice, as the pictures
display faster.
VGA display, capable of 640 x 480 - 256 colors. This requires a VGA
card with at least 512K memory.
Sound Blaster (or compatible) sound card. The program has been
tested with the Sound Blaster V1.5, V2.0, and Pro, as well as Media
Visions Pro Audio Spectrum 16 and Fusion 16 (let me know of others
as you try them!).
This program is designed to display 8 second BLACK & WHITE slow
scan pictures that you can copy off the ham radio bands. The
frequencies that you will normally find slow scan are:
3.845 MHZ
7.171 MHZ
14.230 MHZ
21.340 MHZ
28.680 MHZ
The most popular frequency is on 20 meters at 14.230 MHZ, with
14.233 MHZ being used on weekends when there are too many on
14.230.
The following diagrams might help with the electrical hookup. For
receive, the audio from your receiver needs to be connected to the
microphone input on the Sound Blaster. The audio from your receiver
may come from the speaker output. In my case, I used an audio
output from the back of the radio (Icom 730) that is to be used for
RTTY, Slow Scan, packet, etc. The audio out of the back does not
vary with the volume control, so I can keep the audio at a
reasonable level and still copy pictures.
For transmit, take the audio out (one channel, left or right) to
the microphone on your transmitter. Again, I went into the back of
my radio. With the IC730, you have to use an amplified microphone.
Mine just happens to have a level control under the base so the
level into the microphone can be adjusted down to keep the room
noise from interfering with the picture. Use your microphone button
to key up the transmitter.
Sound Blaster Board V1.5 and V2.0
________________
|
|<---- Sound in from receiver
|
Volume -->|
Control |
|----> Sound out to your microphone input
|
|
|<---> Midi input/output (not used for this
| project)
________________|
Sound Blaster Pro
________________
|
|<---- Line in (not used for this project)
|<---- Microphone in - Sound in from receiver
Volume -->|
Control |
|----> Sound out to your microphone input
| for transmitting Slow Scan
|
|<---> Midi input/output (not used for this
| project)
________________|
I did the development on the Sound Blaster Pro, but I kept the
sample rate at 12 KHZ (the top speed for the Sound Blaster V1.5 and
V2.0) so all Sound Blasters could be used. It seems to give
acceptable results at this speed, however, a faster sample rate
would give even better pictures. In a future version, if there is
interest, I may make a version with extra options just for the Pro
version.
Now that the program has been out for a short while, I've received
feedback from others who inform me that it also works on the PAS16
(Pro Audio Vision from Media Vision) and the Fusion 16 (also from
Media Vision). In this version I am packing the drivers, as some of
the cards, including the V1.5 and V2.0 from Creative Labs, do not
come with the ones needed. Make sure to read about the drivers as
they have to be set up just right to make the thing work.
Copy the program to your hard disk (preferably make a separate
subdirectory called SS). You need all the BGI files for the program
to run. Your computer should have several meg of free space as the
.VOC files will take up about 100k for every 8 seconds of
recording. Also you will want to save some of your favorite
pictures in .PCX files so you can recall them later. The reason I
chose the .PCX format is that it generally a lot less space than
.VOC files. The display on your computer needs to be a VGA display
that will work in 640 x 480 - 256 color mode. Some VGA cards do not
have enough memory to do this. If it doesn't work on your system,
I need to know so I can make the necessary changes. When reporting
problems, please make sure to include as much information about
your computer system as possible (autoexec.bat, config.sys, path,
etc), so I can be of help.
Make sure that in your autoexec.bat that you have the following:
SET SOUND=C:\SBPRO
SET BLASTER=A220 I7 D1 T2
The first line above is telling the computer where your Sound
Blaster programs are located. If your directory name is different
that "SBPRO" then you need to insert the correct directory name
(and throughout the next few paragraphs).
In a subdirectory under "SBPRO" should be a directory called "DRV".
C:\SBPRO\DRV
You MUST have a driver called "CTVDSK.DRV" located in this DRV
subdirectory.
C:\SBPRO\DRV\CTVDSK.DRV
If you do not have this driver, I have included it for to copying
into the DRV subdirectory. However, you must copy the right one for
your card. There are three drivers included:
ctvdsk.v15 for the Sound Blaster version 1.5 & SBMCV
ctvdsk.v20 for the Sound Blaster version 2.0
ctvdsk.pro for the Sound Blaster Pro
If you do not have a file named CTVDSK.DRV in you DRV directory,
you must rename the proper one above to "CTVDSK.DRV" and copy it
to your DRV directory.
The following is an example of how to copy and rename the file in
one step:
COPY ctvdsk.v15 C:\SBPRO\DRV\ctvdsk.drv <enter>
The second line above sets the BLASTER environment which is read by
the program.
The A220 should be the address that you have set your Sound Blaster
at. Other choices could be A210, A230, A240, A250, and A260. The
Pro only has two choices, A220 and A240.
The I7 is the interrupt of the card. Other choices could be I2, I3,
I5, or I10. I would guess that if you already have the card up and
running with other applications, you only need to find out what
you are using.
D1 is the DMA channel used. I believe that in the Sound Blaster
V1.5 and V2.0, you can only use DMA1. However, on the PRO you can
use DMA 0, 1, or 3. DMA 1 is the default.
T2 is the parameter that informs the program which Sound card is
installed.
The choices are:
1 is for SB V1.5 or SBMCV
2 is for SB PRO
3 is for SB V2.0
All of the above are jumpers that you put in place on your Sound
Blaster at the time you installed it in you computer. If you have
questions about what yours is set at, Creative Labs provided a
program called "TEST-SBC.EXE" that gives you the information you
need ("TEST-SBP.EXE" for the PRO). Your Sound Blaster manual will
give you further details.
To start the program after it is loaded type "SS8".
Once you have the audio connected, and a station ready to transmit,
pressing F2 will start the receiving process. The sound is stored
in a disk file named "TEMP.VOC". This file is overwritten every
time you press F2. You will not see anything happen until you press
ESC which should be pressed as soon as the audio for the picture
stops. The "TEMP.VOC" file will be a minimum of 100k in size for
one 8 second period, so you will need to make sure that you have at
least 500k free on your hard disk where ss.exe is loaded (several
megabytes would be even better). You will learn after using the
program that it takes a little bit before it starts recording, so
you need to anticipate the start of the picture just a little.
If you anticipate too much, you can do a couple of different
things:
1. Press ESC will stop the recording & start to display whatever
there was to that point
- Pressing ESC again will stop the display
- Pressing F2 will restart the recording.
2. If, after you are displaying the picture, you see that the top
of the picture is part way down on the screen,,pressing the space
bar will make the rest of the picture restart from the top so you
will see a complete frame.
Note: I know that it is pretty slow by not copying the picture to
the screen as it is coming in, but that may be changed in a future
version.
Once you have a picture on the screen, if you Press F2 again you
will loose the one you have. Menu item F7 allows you to save the
picture as a .PCX file, or you can rename the "TEMP.VOC" file to
another name so when you press F2 again, you do not loose the
picture. I have, just for the fun of it, looked at the .VOC file
and edited them in VEDIT which comes with the Sound Blaster.
Even though I wrote the program code for 8 second Black & White, I
have been able to receive 36 second, 72 second, & SCOTTY 1 in Black
& White. A portion of the picture gets thrown away (you only see
the left hand upper corner) but, I was quite surprised when I saw
how well it did.
Transmit has been added with two options.
1. Pressing F4 will transmit "TEMP.VOC", the last picture
received.
2. Pressing F5 will give you a menu of ".VOC" files that
you have saved. By saving the "TEMP.VOC" file to other
names, you can later re-transmit the pictures you have
received. It's just like a tape recorder!
Help is built into the program and accessed by pressing F1. This
will give you a second menu of help items. Just press the F key
that will give you the information that you want.
Test images are built in, but, other than nice to look at, are of
little use until there is a send program (one that reads the
screen) written.
The CONTRAST, SYNC, and BLACK can be adjusted if desired. This is
left over from my development stages & was left in. It may give you
more insight into how a Slow Scan picture works by playing with
these. Once you have recorded and have a "TEMP.VOC" file, you can
use this file under the F7 option to re-display as many times as
you like using the SYNC, CONTRAST, and BLACK. For those not
familiar with Slow Scan, there are many different modes. An
excellent discussion is in the January 1993 issue of QST.
Updates from V1.0 to V1.1
Fixed 'divide by zero' when no audio was coming in during receive.
Incorporated *.CHR files in .EXE program.
Added transmit capability by re-transmitting .VOC files.
Included drivers for Sound Blaster in .ZIP package.
I hope this program will give you some enjoyment. If it does, I
would also hope that you will register the program for $20.00. I
have spent over 2 years writing this (not every day mind you) and
it was an exercise for me in learning to program in "C". Well, I
guess something must have worked! Anyway, if I get enough response,
I will get to work and enhance the program with the other modes.
Also, I am interested in any ideas you may have to improve the
program or ideas for other programs for the Sound Blaster. I bought
their development kit, and might as well put it to work. So please
send your $20.00 and ideas for enhancement and other programs you
would like to see (how about copying RTTY or PACKET RADIO with the
Sound Blaster ???). Also, anyone sending in the registration with
$20.00 will receive credit towards any major upgrade to the next
higher level.
Speaking of UPGRADES!!!
SLOW SCAN II for the Sound Blaster is now available! This program
will copy more modes than the original version. It will copy ROBOT
8, 12, 24, 36 second Black and White, and ROBOT 36 and 72 second
COLOR (in Black and White), and Scotty 1 and Scotty 2 (in Black and
White). And, like SLOW SCAN 8 second version, you can transmit the
.VOC files to send pictures as well! The price of SLOW SCAN II is
only $40.00. If you are a registered user, the $20.00 that you have
already paid will be credited, so it will only cost you $20.00
additional.
SLOW SCAN COLOR will be worked on, with a release date expected
towards the end of 1993. Depends on how busy I am at my "real" job!
I will also be working on copying REAL TIME. No promises yet,
though I should be able to do that.
Comments or questions can be left for me on Compuserve. Make sure
that you address to Gene Harlan 76645,2455.
Questions can be answered evenings at (815) 398-2683. I'm usually
home by 6:00 pm (CST) unless I have meetings, etc. I have enjoyed
helping those that have called to date. All the comments and
compliments were appreciated!!! Compuserve is probably easier and
I try to check it once a day when I'm in town.
Please send the following registration form to:
Gene Harlan - WB9MMM
5931 Alma Dr.
Rockford, Illinois 61108
Registration Information
_________________________________________________________________
______ I have enclosed $20.00 and would like to register the Slow
Scan program.
______ I am a registered user and would like to upgrade to Slow
Scan II for $20.00, which copies 8, 12, 24, 36 second Black
and White and 36 and 72 second color (in Black and White)
and Scotty 1 and Scotty 2 (in Black and White). Please
include $5.00 shipping (Illinois residents include $1.25
tax.
______ I am not a registered user yet and would like to get the
Slow Scan II program. I am enclosing $40.00 plus $5.00
shipping (Illinois residents include $2.50 tax).
______ I am not a registered user, and cannot afford it at this
time. However, I like the shareware version and would like
to be on your mailing list. If I use the program, as soon as
I can afford to send money, I will. In the mean time, I'll
get on the air and tell everyone how great it is!
______ I just won't buy it until you include COLOR. Please let me
know when COLOR SLOW SCAN TV for the Sound Blaster is
available.
Name_________________________________________
Call Sign______________________
Street_________________________________
City___________________________________ State __________
Zip__________
Type/speed of computer __________________________________
Size of hard drive ______________________________________
Type of display card ____________________________________
Ram - how much do you have ______________________________
Sound Blaster _____ Sound Blaster Pro _____ SB20 _____
PRO AUDIO SPECTRUM 16_____ FUSION 16 _____ OTHER __________________
3 1/2 disk _____ 5 1/4 disk _____
Other information - ideas - suggestions
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________