WinIIr

WinIIr is a filter synthesizer and analysis tool that enables users to design digital IIR (infinite impulse response) filters, with results similar to those of much more complex software, such as Matlab. The application also comes with an integrated code editor and analyzer, providing a complete toolbox for filter design.

The main window includes two panels with diagrams that show the frequency and the time response, respectively. Unlike the step response, the time response reveals the filter’s response to a sine wave burst and the Marker frequency. For each diagram you can easily choose between linear and logarithmic frequency scales and set the minimum and the maximum frequencies yourself.

For those who are accustomed with filter design, all the features of WinIIr will surely be self-explanatory. The application’s controls are displayed in the left-side panel and no other menus with options are available, making WinIIr easy to work with.

Relying on the biquad architecture, WinIIr can calculate and implement four types of filters, namely low pass and high pass filters and band pass and band stop filters. Each filter type has three implementation modes: Butterworth, Chebyshev and Cauer (Elliptical). For the last two, you must specify the maximum accepted ripple. Moreover, the a Cauer filter also requires the attenuation to be entered.

The integrated code editor displays the description of the filter in text format, storing all the data in readable form. The description includes the creation date and the used parameters, as well as the C source code for the quick implementation of the filter.

WinIIr is easy to use for those who are familiar with filter design and calculation, providing precise filter synthesis. It allows the analysis of the frequency and the time response of a filter, allowing the quick optimization of its parameters. All the filter descriptions are stored in human readable form, which makes the data extremely easy to work with.