8 votes

Mapping of Classic Filters for Digital Filter Design

I'm convinced that depending on the problem we're trying to solve, we can and should use both approaches: the transformation of classic analog filter designs, and the direct design in the digital ...
  • 81k
7 votes
Accepted

Mapping of Classic Filters for Digital Filter Design

and simulation where "copying the analog" would result in the better solution. That' missing the point a bit. It's not that one cares much about matching or copying the "analog" ...
  • 34.2k
5 votes

Mapping of Classic Filters for Digital Filter Design

How to Massively Reduce the Resource Requirements in FIR Filter Approach The two answers provided by Matt and Hilmar are both excellent and provide great insight in answering the question. I am ...
  • 38.4k
4 votes
Accepted

Chebyshev I or Chebyshev II?

The decimation operation, under some acceptations, consists in low-pass filtering the data before downsampling it. The standard in Python scipy.signal.decimate, in Matlab decimate: Filtering Before ...
3 votes
Accepted

Optimal Chebyshev FIR filters

The Chebyshev criterion minimizes the maximum weighted absolute error: $$\epsilon=\max_{\omega\in\Omega}W(\omega)|H(\omega)-D(\omega)|\tag{1}$$ where $\Omega$ is the union of all frequency bands of ...
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2 votes
Accepted

Different formulations of Chebyshev II resulting in different poles?

I found out what I was doing wrong. Of course it was my mistake, not the authors of the authoritative text on DSP. I misunderstood the meaning of the parameter $A$ in the Rabiner and Gold formulation. ...
  • 163
2 votes
Accepted

Understanding the Chebyshev2 Bandpass Filter Poles-Zeros Plot

Why is the Chebyshev2 plot so different from the others? Because something is really wrong with your code or plotting routine. The poles of Butterworth filters are NOT real and it should look like ...
  • 34.2k
1 vote

how to plot analog filter impulse responce and frequency responce?

An easy way to accomplish getting the impulse and frequency response for the filter given as a cascade of two second order filters (sos) is to first combine the two filters by convolving the ...
  • 38.4k
1 vote

plot the frequency responce of a sos Analog chebychev filter using python

To use sosfreqz you would first need to map your poles and zeros that are in the continuous-time s domain to the discrete-time z domain (see this post and this post ...
  • 38.4k
1 vote
Accepted

What is Passband Ripple?How is this expressed in dB scale?

What is Passband Ripple? Passband ripple $\delta_1$ is typically specified as the 0 to peak difference in the passband gain in the magnitude response of a filter. For a filter with unity gain (1), ...
  • 309
1 vote

how to convert the zeros of an odd order Chebyshev Type II from low-pass prototype?

This is a bit easier to see if you look at the zeros directly and not at the numerator polynomial, i.e. [z1,p1,k1] = cheby2(order,40,Wo, 'high'); Odd order lowpass ...
  • 34.2k
1 vote
Accepted

Chebyshev Filter Transfer Function

Note that the squared magnitude of the frequency response is given by $$\big|H(j\omega)\big|^2=\frac{1}{1+\epsilon^2T^2_N\left(\frac{\omega}{\omega_c}\right)}\tag{1}$$ In the $s$-domain we have $$H(s)...
  • 81k
1 vote
Accepted

Typical parameters and stability of Chebyshev filters

I design Chebyshev first and second type filters You are not going to see a lot of effect with this low order filters. If you want to study ripple and attenuation crank it up. What are typical ...
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