** Frequently asked questions **
** Frequently asked questions **S/FILSYN was developed on main-frame computers and operates in the question - answer format used by computers of that era. The latest "PC" implementation uses script program files to automate this format for most commonly used filter types. This combination provides unparalleled synthesis power.
PCFILT does most of its designs by scaling normalized reference lowpass filters. PCFILT does provide a pole-placer, but it is limited to conventional (not parametric), equal ripple passband response only. This means that the sum of the extreme zeros (at DC + those at infinity) must equal an even number. There can be up to 9 finite zeros (stopband notches) located anywhere above and / or below the passband placed at ay frequency. S/FILSYN will also do "parametric" synthesis. This only requires one odd number of extreme zeros.
PCFILT uses a menu-driven interface which has been set up to allow maximum flexibility and operating speed for quick design of all of the most common filter types. PCFILT is heavy on analysis with Fourier analysis in the time domain, power analysis to display voltage and current at any point in any filter and convenient graphic plotting and optimization. PCFILT can also input designs from S/FILSYN for analysis or circuit transformations with its mouse-operated point-and-click circuit editor.
Put simply, S/FILSYN is for the "scientist" who has a few very demanding requirements to satisfy. PCFILT, on the other hand, is for the "technician / engineer" who needs a lot of different filters fast.
Actually, if you have BOTH programs, you will have the best of both worlds!
S/FILSYN has been available for may years and its reputation is well established. Just ask anyone who designs filters. He will tell you about S/FILSYN!
ALK Engineering bills on a "net 30 days" basis. If, after 30 days, you don't like one of our key-protected products, simply return it and ignore the invoice! Isn't that better than a "demo" that doesn't really do anything useful?
PCFILT and S/FILSYN are the two best and most sophisticated filter design software programs ever written. Even an experienced filter designer will find new things in the software he will need help on. If the extensive users guides we provide do not answer your question, one of our three consultants (the program authors, no less) will be available to help you at no extra cost for as long as needed. Help is as convenient as your telephone, fax or e-mail.
PCFILT and S/FILSYN can share the same key if they are to be used on the same computer. They may also use separate keys. This is YOUR choice.
1-Failure to see the hardware key.
2-Improper setup or use of the REXX script system.
First, test to see that S/FILSYN is reading the key. From the DOS command line, type:
C:\SF>PASSIVE (Enter)
If the key is being read you will see this:
***** S/FILSYN *****
RELEASE 3.3 VERSION 2 2/1/99
** PASSIVE/MICROWAVE SEGMENT **
Copyright (C) 1983 - 1999 Dr. George Szentirmai.
All Rights Reserved.
SYNTHESIS: S, ANALYSIS: A OR END: E
IF S/FILSYN can NOT see the key, you will see this:
Stop - Program terminated.
If S/FISLYN can not find the key, contact ALK Engineering. If the key IS being read, your problem is most likely with the script system.
When using the REXX system, the errors are usually one of the following:
Do NOT type: REXX FILEMENU (Enter). This looks like its working, but it ISN'T!
If you type: FILSYN (Enter). This will do nothing at all under REXX. This WILL work under the EBL system.
DO THIS: C:\SF>REXX FILSYN (Enter)
If this causes and error message the REXX memory resident programs are not set up correctly. See the file rexx.txt on the distribution disc.