Intermodulation Products Calculator

JohnEB

Newbie
Joined
Mar 29, 2026
Messages
2
Reaction score
0
Hello All,
Recently I have returned to computer programming.
I have found some of my old programs, written in the 1980s and 90s.
I have written new batch scripts and utilities to go with some of these.
One of these programs is INTMOD version 5.4, which I wrote in 1989, as INTMOD54.COM.
Along with some batch script files and utility programs, I have placed it in zip INTMOD54.ZIP.

Is there a way I can upload this file please, so that members of the forum can download it and try INTMOD54, perhaps even find it useful?

INTMOD54.COM is an MS-DOS program but requires and will not run without, the ANSI.SYS driver.
As I cannot find my source code files and I wanted to make changes to the output file, I have written a sub-menu system in Windows XP batch script.
So the best way to run it is in a Windows XP (or perhaps other 32 bit Windows or DOS emulator) system.
In the zip are:
ECOL.COM - Coloured text for batch scripts
IMFUPR.TXT - EDLIN input script file
IMFUPV.TXT - EDLIN input script file
Intermod.bat - Main batch script to run this package
INTMOD54.COM - Original 1989 MS-DOS program written in Mix C. Needs ANSI.SYS loaded.
KTDel.bat - Batch script subroutine called by Intermod.bat. Also needs EDLIN and FIND system utilities.
SBC.COM - Set background colour for batch script text.

INTMOD54.COM can output a text file of Intermodulation Products, called INTMOD.DAT.
The main thing that the batch script does, is rename this file to INTMOD.TXT and open it in Windows Notepad.
It can then be given a unique name and saved from Notepad, if required, as INTMOD.DAT/TXT are overwritten on successive runs.
Another option in the batch script sub-menu removes known transmitter frequencies from the list of intermodulation products.
If you have several large signals intermodulating, you would be unlikely to notice an intermodulation product on the same frequency as one or more of them.
So to reduce clutter, this option removes them by carrying out an automated edit routine on the output file, using FIND and EDLIN system utilities.
The full file can still be viewed, if required.

To use:
Unzip the file to a directory/folder of your choice.
If using MS-DOS you will only need INTMOD54.COM as the batch script will not work. You will need - DEVICE=ANSI.SYS added to your CONFIG.SYS file.
For Windows XP (and possibly other 32 bit Windows systems)
Make a copy of CONFIG.NT and call it CONFIG.ANS (or whatever), edit it to add the line - device=%SystemRoot%\system32\ansi.sys
However you created CONFIG.ANS, make sure it resides eventually in the Windows\system32 directory/folder.
Now go to the folder containing INTMOD54.COM and right click INTMOD54.COM and select Properties.
Select the Program tab and then click the Advanced button.
Change Config filename: from CONFIG.NT to CONFIG.ANS (%SystemRoot%\SYSTEM32\CONFIG.ANS)
The above upper/lowercase etc is as I have found on my EeePC running Windows XP.
Having done all the above, you can double click Intermod.bat from File Explorer or even send Intermod.bat to the Desktop as a shortcut.

If it runs and quickly terminates, the most likely cause is that the ANSI device driver has not loaded.
Open a CMD window in the directory/folder containing INTMOD54.COM and type intmod54 at the prompt.
You will then see if it complains that the ANSI driver is not loaded.
If that is the problem, check the work above to make sure all is correct with CONFIG.ANS.

Once you have resolved any problems, you should be presented with the 3 option menu from INTMOD54
As an example:
Select option 1 and enter some frequencies, say:
Number of known transmitter frequencies: 3
TX 1: 89.7
TX 2: 91.9
TX 3: 94.1
The observed receiver range can be from: 87
To: 108
Lowest order product: leave at 2 or change to 3
Highest order product: leave at 3
Program runs and output appears on screen + More.......
Enter to see the rest until the single line menu appears.
Select F to create a results file. Message INTMOD.DAT created.
Now select Q to quit (yes, it seems wrong but it will take you to the batch script sub-menu.)
At the sub-menu select V to view the full results as previously displayed on screen or R to remove any instances of 89.7/91.9/94.1
View the results in Notepad.
Close Notepad to return to the main 3 option menu.
Select 3 to close the program..... or 2 to experiment with finding an unknown TX that may be the cause of an observed intermodulation product.

So if it is possible to upload this somewhere/somehow, please let me know and I will share this program with you.
If upload of programs is not allowed, please tell me and I will go away and not bother you again.

Best regards, John.
 
Top