One of the things I do when learning a new language is to pick a program I want and code it up in that language. As part of some future projects I will be working on, I need to design some audio filters, so I dusted off some old information I had, and spent a few hours whipping out some quick and dirty code to design FIR filters using Fourier Series in C#. Even though there are several sites on the web that will allow you to do this, finding source code for it is a bit trickier. A lot of the DSP links that I ran across in my hunt seem to be broken. As a result, I decided to put my code up for anyone to use that may need it.
The program walks you through several windows forms to define the filter type, sample rate and corner frequency or frequencies, the number of taps, and the window type. You can then calculate the coefficients with the click of a button and they are automatically saved in a text file. If you want, you can plot the response of the filter just designed with linear or logrithmic scales for amplitude and frequency.
The program is a Visual Studio 2005 C# program. The source for the project is available in the zip file below if you want to take it apart to see how it works, or modify it. There are no restrictions on the use of the source code, so have fun.
Here is a link to the project source code. Project source
If you just want to run the program to generate coefficients, I have a zipped file below that you can download and unzip on your machine. It contains the minimum number of files needed to execute the program. After you have unzipped the folder, and moved it to where ever you want it to live on you machine, just go into the folder and double click FourierFIR.exe.
Here is a link to the executable. Executable
Here is a link to the project source for a version with 16 bit and 32 bit coeffs. Modified project source