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Category Archives: Biquads
About coefficient conventions
It’s been asked many times, so it’s worth an article explaining the conventions used on this site for transfer functions, and why they may differ from what you see elsewhere. People run into this most often with biquads: I use … Continue reading
Posted in Biquads, IIR Filters
7 Comments
Evaluating filter frequency response
A question that pops up for many DSPers working with IIR and FIR filters, I think, is how to look at a filter’s frequency and phase response. For many, maybe they’ve calculated filter coefficients with something like the biquad calculator … Continue reading
Posted in Biquads, FFT, Filters, FIR Filters, IIR Filters
27 Comments
Biquad C++ source code
I don’t want to get into the business of teaching people how to code—there are a huge number of free resources available on the internet to that do that. But I’ll give a small taste for those trying to get … Continue reading
Posted in Biquads, Digital Audio, Filters, IIR Filters, Source Code
73 Comments
Biquad formulas
For fixed filters, we can plug biquad coefficients into our programs. But often, we need to calculate them on the fly, to user settings or changes in sample rate. As a companion to the biquad calculator, here are the formulas … Continue reading
Posted in Biquads, Digital Audio, Filters, IIR Filters
48 Comments
Biquads
One of the mostused filter forms is the biquad. A biquad is a second order (two poles and two zeros) IIR filter. It is high enough order to be useful on its own, and—because of coefficient sensitivities in higher order … Continue reading
Posted in Biquads, Digital Audio, Filters, IIR Filters
30 Comments