Why is QuickFil so fast?

QuickFil uses simple algorithms, and a multi-precision arithmetic to solve some numerical problems of these simple algorithms. The overall performance is much better than you can achieve using some special algorithms and standard IEEE floating point numbers using the coprocessor. Further due to Assembler programming of the multi-precision arithmetic a further speed up of a factor 5 is achieved.

Why do you claim that it is easy to use?

Unlike other filter design products QuickFil checks the inputs fields during your input. You can investigate the specifications and modify them in an easy way. You can change one parameter and define which other parameter should change too. For example you can decrease the stopband loss for getting lower passband loss or a lower stopband edge frequency. You can define, which parameter should change. Further there are some helpful information like the filter quality and the 3dB edge frequency. At the passive design step you can define the circuit in an easy way step by step. You don´t have to know anything about the internal designing steps, you only choose parts of the circuits, which are allowed at that step.

Some circuits will not be realizable, because there are negative elements included. Since it is not possible to see this fact at the beginning, you have to try different circuits. Now QuickFil has included a powerful tool to find circuit, which are realizable. There is a search algorithm included, which will search for realizable circuits systematically. This feature demands a very fast design algorithm, which is available for QuickFil.

What is the difference in filter approximations to other filter design programs?

There is no program available, which will support the user with so much information at the designing step. Normally the specification part of a filter design program is a list of data, which you have to specify and afterwards the program will tell you, that it is OK or not. Using QuickFil you will see the difference. You are checked at every number input and you can modify the set of data, until you are satisfied. Although elliptical filters use very complicated mathematics, all these checks are done for elliptical filters including the necessary frequency transformations (case b and c) too. These features are interesting for system designer to estimate the costs of the filters, which is an important parameter of every new idea.

There are many filter design programs available, but you will find no program, which can design following filter approximations in such an easy way:

You can design equal ripple or maximally flat passband response and arbitrary stopband performance. You define the stopband specifications in a step profile and the program will optimize the position of the transmission zeros. You can define fixed transmission zeros too, which can be used to suppress pilot carriers.

Further you can specify parametric bandpass filters, which are interesting for filters having minimum number of inductors.

Although the calculation of the 3dB edge frequencies and the filter quality is complicated, these values are available for these approximations too.

For getting a better group delay response you can add an allpass to the minimum phase filter. There is a special least-p optimization algorithm included. For getting better results you can include a frequency independent delay as a further parameter of the optimization, since the overall delay isn´t important normally.

Further you will have Bessel and modified Bessel approximations, which are very easy to design, since you can define the stopband edge frequency, which isn´t available at other filter design programs.

Is there any help available?

Yes, the program includes an online help for every menu. There you will find the most important information to the specify topic. Further information you will find in the manual.

For which operating systems is QuickFil available?

QuickFil is a DOS program. But it will work at every modern Windows operating system in a DOS Window (full screen). Further there is mouse support. Normally the program is available using a Windows installation program, which will install the program at any Microsoft Windows operating system, including an uninstall program.

What printer does QuickFil support?

Since QuickFil is a DOS program, no Windows printer driver is used. But there are some DOS drivers included and you can print ASCII to almost every printer using any parallel port directly or you can redirect the parallel port to a network printer. Further you can print graphics to the printer too using special drivers included in the program. Please try the demo version.