# Tag Info

Accepted

### Which order to perform downsampling and filtering?

You need to filter first and then downsample. Otherwise, you will run into aliasing problems. I.e. frequencies that are above 30 Hz will create images within your frequencies of interest. You can ...
• 6,218
Accepted

### Is there an adjective describing a filter with kernel that has zero mean?

"Zero-Mean" is the word that's commonly used to describe signals and signals with a zero average. "This is a zero-mean filter." If you really mean a filter that is specifically ...
• 30.6k

### Frequency Domain Filtering

This is just "faking" the magnitude response of an IIR filter. The output's magnitude spectrum looks just like it has been filtered by the IIR filter with the given frequency response. Although it may ...
• 4,285
Accepted

### SOS-matrices' order does not correspond to given parameter when designing bandpass with scipy.signal.butter

Your expectations are reasonable. However, the definition of order in the design routine is confusing. It's the same in Matlab/Octave. For lowpass or highpass ...
• 90k

### Filter odd or even harmonics with notch or inverse notch filter

What you are looking for are what we, in the audio space, call comb filters. Comb filters may or may not have a feedback path, just like FIR and IIR filters. In fact, there is a generalized theory ...
Accepted

### Frequency Domain Filtering

This sort of filtering is done all the time, but it doesn't have the effect you think it should. Suppose you have an IIR filter with an impulse response of $h[n]$ which is represented in the $z$ ...
• 25.7k

• 90k
Accepted

### IIR filter relationship between number of poles, order and second order sections

The filter order equals the number of poles, that's a fact. How people call and use parameters in software is a totally different question. Many routines that design standard IIR filters use frequency ...
• 90k
Accepted

### What is the relationship among digital filter cutoff frequency, signal frequency and filter settling time?

With "Settling Time" we can consider the overall time delay of the filter, and the rise/fall time of a transient change going through the filter. The rise/fall time will inversely related to ...
• 51.3k
Accepted

### Bandpass Stationary Stochastic Process

I've been a bit hesitant about adding another answer to the existing ones, but since no answer has been accepted yet, and since from Dan's own answer it seems to me that there might still be a few ...
• 90k
Accepted

### Given two low-pass digital IIR filters, find bandpass coefficients

It's true that only impulse responses of linear phase (FIR) filters can be added or subtracted (if the delays are aligned) such that the resulting filter's magnitude response equals the sum or ...
• 90k
Accepted

### Bandpass general equation to difference equation

The transfer function of a continuous-time second-order band-pass filter is given by $$H(s)=\frac{\frac{\omega_0}{Q}s}{s^2+\frac{\omega_0}{Q}s+\omega_0^2}\tag{1}$$ where $\omega_0$ is the center ...
• 90k