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Category Archives: FIR Filters
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
23 Comments
Convolution—in words
Convolution is a convoluted topic—and that’s what it means (convoluted, from MerriamWebster : “Extremely complex and difficult to follow. Intricately folded, twisted, or coiled.”). Really, it’s more difficult to explain why you would want to use convolution than it is … Continue reading
Posted in Convolution, Digital Audio, FIR Filters, Impulse Response, Reverb
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Sample rate conversion: up
Once we have a suitable set of FIR filter coefficients from our windowed sinc calculator, it’s time to apply them. Again, our recipe for doubling the sample rate: 1) Insert a zero between existing samples. (This is the upsampling step, … Continue reading
Posted in Aliasing, Convolution, Digital Audio, Filters, FIR Filters, Sample Rate Conversion
7 Comments
Towards practical resampling
In a previous article, we looked at sample rate conversion in the frequency domain. Let’s take a quick second look in the time domain as reinforcement of principles behind sample rate conversion, before developing a practical rate convertor. In an … Continue reading