Questions tagged [biquad]
Biquad is referred to either analog or digital second order filters
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How to match coefficients of a SVF compared to Biquad in order to Plot the frequency response?
I'd like to output the frequency response of this filter.
Here's how the coefficients are calculated:
...
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Is it possible to lower the slope of a biquad lowpass? [duplicate]
I'd like to implement a lowpass with arbitrary slope. I'm currently cascading biquads in order to get a higher order, hence higher slope. But is it possible to do the opposite - lower the slope of one ...
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using scipy.signal.sosfilt to filter a stereo signal with zi, zf
I'm stuck trying to filter a two-channel signal using sosfilt() with the zi initial state. I need to use the zi parameter so I can carry the filter state over ...
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design of cascaded biquad filter
I have to compare the response of an 8th order IIR filter and its equivalent 4 stage cascaded biquad structure. A sinusoidal signal is given as input to both the systems and the output responses are ...
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BPF design as cascaded second order biquads
I am trying to design a bandpass filter in MATLAB with following specs:
$$\texttt{f_s = 20000Hz}$$
$$\texttt{3dB freq = [392 464]Hz}$$
$$\texttt{filter order = 8}$$
When I tried to implement the ...
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Pole Quantization Patterns in 2nd Order IIR Resonators
Background
My typical approach to fixed point design for digital filters is to iteratively scale and increase quantization while comparing the fixed point simulation to the floating point design ...
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Series vs Parallel Biquad Filters
What are the pros and cons of arranging a set of biquad filters in series and parallel? I gather that series should be used in cases where the filters contribute to the same passbands and vice versa ...
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How to calculate IIR Lattice Filter Coefficients for Biquad Filter
If I have a biquad filter with known $a_1, a_2, b_0, b_1, b_2$ coefficients, how do I calculate the corresponding lattice/ladder coefficients?
I have found information on deriving the lattice ...
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What procedure to find the parameters of a given filter prototype to fit a desired frequency response?
To model the frequency response of a system, I am looking for a method to fit the response of cascaded bi-quad filters to the response of that system using an optimization algorithm. The $S$-domain ...
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How to implement cascaded biquad transfer functions in Python/SciPy
I am trying to implement in python/Scipy the biquad filter with the following S-domain transfer function:
$$
H(s)=\frac{w_0^{2N-1}(s+w_z)}{[s^2+(w_0/Q)s+w_0^2]^N}
$$
My problem here is that because of ...
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Discrepancy in frequency response of biquad filter (in Python)
I have written a simple biquad filter class but when I check its frequency response, I get different results with different methods. If I check it "empirically" (by taking the FFT of its ...
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What is the $Q$ of successive Second-Order Sections of an $N$th-order Butterworth low-pass filter?
What if you had an $N$th-order Butterworth lowpass filter filter with -3 dB frequency of $\Omega_0$?
$$ \Big| H(j\Omega) \Big|^2 = \frac{1}{1 + \left(\frac{\Omega}{\Omega_0}\right)^{2N}} $$
The number ...
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ELI5: How do biquad filters like bandpass "know" the frequency of a signal?
I understand the code behind biquads, but I fail to understand how 5 coefficients in a biquadratic formula can isolate frequencies so precisely, especially considering it only takes the last two ...
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High pass biquad cascade transposed direct form II low frequency accuracy
I'm quite new to DSP and I'm trying to implement high pass biquad cascade in transposed direct form II. Currently my implementation has very poor accuracy at cutoff frequencies that are less than 5kHz ...
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How to optimally normalize filter coefficients?
I have designed an IIR filter in Matlab that comprises the following biquads
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Derive Time-Domain Biquad Coefficients from Z-Domain
I'm trying to derive the time-domain coefficients of a biquad filter based on its z-domain coefficients. The purpose is to import externally-generated EQ filters (in z-domain) into Max/MSP (in time-...
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Biquad cascading frequency response
I am implementing EQ lines in my filter. I need to do biquad with slope 24 db/oct, 36/oct and bigger so I would like to cascade several biquads. I am stuck with calculating frequency response of two ...
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Direct form 1 filter equation for a biquad filter
In general, we all know that the direct form 1 equation for a biquad filter is given by
$$y(n) = b_0x(n) + b_1x(n-1) + b_2x(n-2) - a_1y(n-1) - a_2y(n-2)$$
But when it comes to practical applications ...
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Converting cascaded biquads to parallel biquads
I need to convert a fourth-order IIR filter made using two cascaded second-order sections with the transfer function:
$$
H(z) = \frac{b2_{1}z^{-2} + b1_{1}z^{-1} + b0_{1}}{a2_{1}z^{-2} + a1_{1}z^{-1} ...
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Calculating the true values of biquad filter coefficients from normalized form
I have a C code in which the IIR filter(BiQuad) uses only 4 (normalized) coefficients per stage (a2/a0,a1/a0,b2/b0,b1/b0) instead of 6 coefficients (a0,a1,a2,b0,b1,b2). I know that the value of a0 is ...
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IIR Cascaded Filter Response, Unexpected Results
I am attempting to understand how to manipulate portions of a cascaded series of biquad notch filters in a control system I am working with.
As part of determining the composite response of all the ...
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How do you calculate the group delay in samples of a Biquad Filter at a given frequency from the coefficients?
If I have a BiQuad all-pass filter with a given set of coefficients such as:
g: 0.903228
a1: -1.88142
a2: 0.903228
B1: -2.08299
B2: 1.10714
And my operation per ...
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Biquad high-pass filter not working as expected
I'm trying to implement a high-pass filter using the the coefficients described in RBJ's well-known EQ cookbook (see https://www.w3.org/TR/audio-eq-cookbook/).
However, when I run white noise through ...
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bibliography about implementation of IIR filters
I need to implement a 6th order IIR filter. The filter I need to implement is the A-weighting. I've simply used the bilinear function of Matlab with an fs of 20Khz. I need to implement this over the ...
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Biquad Filter Non-Linearity
I'm using a biquad filter algorithm in my project. I got 3, 16 size variable arrays summing into one and then gets filtered.
Now i want to filter each array seperately and sum after that, which if the ...
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Biquad Type-II Coefficient Generation
I have a Biquad II filter implementation in my embedded environment and I'm trying to find some equations to generate the coefficients for it.
I have already found the Audio Eq Cookbook, which simply ...
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Why does my low pass filter diverge below 7000 Hz?
I'm trying to create a LPF, using language JAVA. My first aim is to understand how filters design is working and the second one is to create a "home made" equalizer with "home made" filters.
To help ...
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Known problems with IIR DF2 when using 64-bit floating point processing?
So far I was using DF1 for biquad filters for audio DSP, but it turns out that it is possible to gain significant performance gains using the new AVX/AVX512 instruction sets using DF2. Are there any ...
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Biquad and polarity flipping
Assuming normalized biquad coefficients:
$$
H(z) = \frac{b_0 + b_1z^{-1} + b_2z^{-2}} {1 + a_1z^{-1} + a_2z^{-2}}
$$
And taking the definition of flipping the polarity as multiplying every tap in a ...
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Issue with the Massberg Analog-Matched Low Pass Filter
Implemented the filter mentioned in title using Octave and couple sources Vicanek and Zeitlin (LPF.cpp). Got filter working otherwise but, ... when tested the responses against 'analog model' of the ...
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How would I calculate the state-variables of digital biquad filter (direct form II transposed) at steady-state?
I'm attempting to calculate the steady-state state variables for a digital biquad filter direct form II (transposed). Illustration
For example, let assume the filter is fed a constant input of ...
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Help with audio EQ cookbook BPF filters and Q
I am fairly new DSP, and am using maths that I have not used in 20-30 years. I have been working with Cookbook formulae for audio EQ biquad filter coefficients by Robert Bristow-Johnson and am having ...
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Can a Goertzel filter response be mapped to a Direct Form II Biquad IIR Filter
I am looking at the structure of the Goertzel Filter, and it seems like I can map its coefficients to the standard implementation of the CMSIS DSP Biquad Cascade IIR Filter. Is this possible or should ...
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Biquad Treble Shelf filter gain being weird
Trying to compute Biquad Coefficients for use in a codec chip TLV320AIC3100.
Bass Shelf(boost and attenuation) work as expected. Treble Shelf attenuation works as expected but Treble Shelf boost is ...
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Is it possible to combine two or more Biquads?
I've wrote a Equalizer, and now it apply the Biquads in serie (cascade), I was just thinking if i can combine the biquads it will more efficient than applying one-per-one.
Is that possible?
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Avoiding clicks with changing biquad coefficients
I have a DSP application that filters a signal with five cascaded biquads whose coefficients are determined by the Audio EQ Cookbook formulae (Thanks for this work, Mr. Bristow-Johnson btw). Each ...
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PeakEq center frequency does not match frequency response
Following the Cookbook i calculed these coefficients:
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How do scaling of the coefficients for the poles of a biquad filter affect the gain?
Given a digital filter consisting of a chain of digital biquad filters.
Given a digital biquad filter with a normalized Direct form 1 difference equation: $ y_n = b_0x_n + b_1x_{n-1}+b_2x_{n-2} - ...
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Software implementation recipe of cascaded Biquad IIR filter
I have been given the task of measuring the performance of Biquad IIR filters on a new CPU that we are evaluating.
What I know is that the Biquad filters can be cascaded to form higher order filters.
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IIR biquad real-time filter just output noises
I've implemented a IIR filter but it outputs only noise (like FM radio out of tuning) and I can't see what's wrong.
This is the processing function:
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4th order high-pass filter on a DSP: standard or biquads?
I have two C implementations of 4th order high-pass filter (fs = 16 kHz, cut-off=100 Hz, designed using Matlab ...
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What's the point of MATLAB's scaling array for secord-order-section filters?
I'm currently working on a project where I'm implementing different filter types (e.g. iirs - direct form 1, 2, transposed 1, 2, etc.). I just recently started attempting to implement a second order ...
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Two question about RBJ Peak filter
I'm new into DSP and Filters in general. Its the first step ahead I do from learning and using a 1-pole IIR basic Low Pass Filter.
I'm about to implement for my VST audio application (using C++ and ...
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Filter long audio data using cascading biquad filter
I would like to lowpass filter a long pcm wav file. I designed a 20 order butterworth lowpass filter in Octave and transform the zero pole gain data to a series of second order sections. Then I am ...
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Biquad cookbook formula for broadcast FM de-emphasis?
Can a simple IIR biquad filter be used as an audio de-emphasis filter for broadcast FM radio? If so, how does one translate the filter requirements (50 uS time constant in the U.S.?) into parameters ...
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Is there any audio DSP without biquad constraint?
I found a codec with audio DSP, ADAU1772. It supports 32 biquads, that is $32\cdot5=160$ parameters.
I need to calculate filter coefficients on-line. The result is in transfer function form, i.e.,
$...
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Prewarping both resonant frequency $f_0$ and bandwidth (or $Q$) when using bilinear transform
RBJ's Audio EQ cookbook takes into account only frequency prewarping when case Q is used for bandwidth. Why not $Q$ prewarping as well with some of those filter ...
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Biquad coefficients using Magnitude (or Phase) Invariance Mapping Method
I'm trying MIM (Magnitude Invariance Method) and PIM (Phase Invariance Method) for to improve biquad LPF response at low sampling rates. I'm looking some help and examples of usage if available.
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