Questions tagged [filter-design]

Fiter design is the process of designing a filter.

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What is this similar-but-not-quite-windowed-sinc impulse response?

While implementing/studying brickwall low pass filters for digital audio, I decided to run a unit impulse through FabFilter's Pro-Q 3 brickwall low pass filter to see what the resulting impulse ...
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2 votes
1 answer
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Filter Design - Quantifying the Tradeoffs

Background I've been given the task of designing a filter. The problem is constrained in terms of filter order, and as such, the specs initially conceived for the filter seem challenging, and we think ...
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1 answer
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Filter design with constrained impulse response

What I want I wish to design an LPF, preferably an FIR, but also open to IIR. My constraints: I care about phase non-linearity. Thus if I use an IIR, I need a filter similar to a Bessel filter. My ...
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When is perfect analytic filtering (discrete) suboptimal?

Defined as "negative DFT bins zero", when are such filters suboptimal for AM/FM extraction or related filtering? This answer reads, [nulling] also has the worst performance compared to ...
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37 views

Using kalman filter in R for sine wave frequency estimation

I'm pretty new to Kalman filtering techniques, and have a problem that I'm trying to solve. Imagine in a lake I have a splash generator that sends out sine waves across the lake. At various places ...
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1 vote
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Converting a SISO LTI System to a MIMO LTI System

I have a SIMO IIR filter represented as a state space system. I'm wondering if there is a canonical way of converting a IIR filter into a MIMO system, so I can calculate $N$ terms as input at once and ...
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3 votes
1 answer
250 views

How to get scipy remez to give matlab firpm answer?

If I run this in matlab: h = firpm(100,[0 0.1 0.2 1],[0 0 1 1]) and this in scipy: h = remez(100,[0, 0.05, 0.1, 0.5],[0, 1]) I ...
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Efficient CIC Decimation Filter in C

Does anyone have advice on efficient CIC Decimation filter implementation. I designed a basic 4th order CIC filter with a 64 decimation ratio in C (below). I am currently testing this on a Sharc SC589 ...
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I just computed an DFT and FFT of a sinc function, but when I visualise them the results are strangely different? what am I missing

The idea here is to improve a Sinc function by manipulating its Fourier transform. As you can see, the tophat has ripples in the bands of interest and I want to eliminate them by smoothing them with a ...
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1 answer
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Matching outputs of FIR filters based on time domain convolution method and overlap-save method

I'm trying to match(to the best extent possible) the outputs of FIR filter based on Frequency domain overlap-save method and time domain convolution method resp. I was able to get most of the output ...
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Problem with transforming a tophat to obtain a sinc?

I have observed that the Fourier transform of a tophat function is a Sinc-like function with higher peak sidelobes than an actual Sinc. However, the Fourier transform of a Sinc is a tophat-like ...
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2 answers
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Constraints on number of taps in a FIR filter vs. FFT length

I want to implement a FIR highpass filter for acoustic signals. I generate the FIR using Python's SciPy code: ...
4 votes
1 answer
326 views

Unwanted periodicity in data

my signal consists of data points that represent the (vibration signal) energy measured during process cycles of a machine. Due to the hydraulic power units emptying and filling again, some ...
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3 votes
3 answers
140 views

Time-varying Notch Filter in C

I have a digital notch filter (band-stop) implemented in C. It works very well. The issue is that varying the filter coefficients in order to track a noise signal that varies in frequency results in a ...
2 votes
2 answers
52 views

Bilinear transform for a system in zero-pole-gain form

MATLAB's bilinear performs the following steps for a system in zero-pole-gain form If fp is present, it prewarps: ...
1 vote
1 answer
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Sampling frequency in bilinear transform when designing butterworth filter

I'm trying to design digital Butterworth filter from scratch. First I use butterap to design an analog prototype to get zeros, poles and gain ...
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1 answer
30 views

Why does applying fir filter in R (gsignal package) increase the magnitude of all values?

I am new to signal processing and I am sure this is a very rudimentary question. However I have done various searches and I cannot find an explanation (possibly because my knowledge is insufficient to ...
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2 votes
3 answers
365 views

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

I have some general observations but I am asking if anyone can summarize more conclusively: (1) Filter settles slower if the ratio between signal frequency and filter cutoff frequency is smaller; (2) ...
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1 vote
1 answer
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how to design the $\text{sinc}(\cdot)$ filter for OFDM oversampled system

We usually zero-padding into the moulated data of OFDM before performing IFFT operation to make the design of anti aliasing filters easier ( the cut off can be less sharp) hence save cost. That ...
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Analytical derivation of convolution and multiplication implement of time-domain signal

I have a system model as shown in figure 1. I want to change the model to a new schematic as in figure 2. How to analytically derive the filter $H_2$ if all parameters are known? I guess that we will ...
2 votes
1 answer
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How to design digital Butterworth filter and return its zeros, poles and gain

I'm implementing digital Butterworth filter and encounter some numerical problem when filter order is high using direct form, so I wonder how to design the digital Butterworth filter and return its ...
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1 answer
57 views

MATLAB polystab function: It doesn't seem to be doing anything!

I've been attempting to stabilise an unstable filter (unfortunately, I cannot redesign the filter in a way that it is more stable and that is NOT an option). It is derived from an approximation of ...
2 votes
3 answers
99 views

FIR filter phase response at fs/2

I am currently building a FIR filter based on frequency sweeping data (0 Hz to Fs/2), i.e., transfer curve in frequency with the sampling rate of Fs. The phase response is shown in the following ...
1 vote
1 answer
41 views

Problems designing a notch filter based on allpass in MATLAB

I have to design a notch filter based on an allpass but when I plot the resulting filter in MATLAB it does not fit my specification. I'll provide you with some background. The filter has the following ...
1 vote
1 answer
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Matlab Filter Designer "Filter Information" shows wrong order

I want to design a low pass filter using the Filter Designer tool of Matlab. The filter order should be 10. I chose the Blackman window method and specified the order of the filter. However, "...
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2 votes
1 answer
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A problem on FIR filter design given a difference equation

Given the following difference equation: \begin{equation} y(n)=2x(n-2)+3x(n-5) \end{equation} describing the structure of an FIR filter, design the direct form of one. What is the order of the filter? ...
3 votes
1 answer
252 views

Filter type selection for signal envelope detection

Working on a signal envelope detection code in Matlab in which an RF signal envelope is to be created. The flow is such that filtering is performed according to the detected presence of a signal in a ...
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1 vote
1 answer
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How to create a frequency weighted measurement? / How to design a Pinking FIR Filter?

Disclaimer: I have read a lot about signal processing, but I taught everything myself and therefore have some gaps in theory and practice. I am currently working on a measurement software that is ...
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Low pass filter behavior in frequency domain

I have a relatively simple task, which is to implement a low pass filter for a sum of exponentially dampen complex sinusoids in random Gaussian noise. To showcase my problem I have generated data ...
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Digital slew detection

I'm looking for an algorithm to detect the slew rate of a 50Hz discrete input signal sampled at 400Hz. I'm doing the obvious - so a low-pass filter on (sample - prev_sample) / deltaT but this results ...
1 vote
1 answer
18 views

How to get the time domain of a pulse after an amplitude mask or a phase mask has been applied?

I am a chemist, and I am studying ultrafast spectroscopy. In these spectrscopies, usually a short (femtosecond) pulse of light is used to probe chemical reactions. Now, one of the topics in our ...
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7 votes
2 answers
187 views

Constrained Least Squares Filter Design

I would like to design a complex FIR filter, $h$, for a known signal that produces a desired output: $d$ = $s*h$ (where $s$ is my signal and $d$ is the desired filter output). Let $S$ be the ...
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1 answer
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Confusion understanding filter visualization tool output in MATLAB

My MATLAB code is d = fdesign.bandpass(.3, .4, .6, .7, 80, .5, 60); Hd = design(d, 'ellip'); fvtool(Hd) when i run my script , i see two graphs on output ...
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Windowed Sinc vs Parks–McClellan filter design [duplicate]

In the context of FIR filters, what are the tradeoffs between using a low pass filter designed using a windowed sinc versus an optimally iterative algorithm such as Parks-McClellan? When would you use ...
1 vote
0 answers
32 views

Single Kalman Filter: Resistance based on measurment of current and Voltage [closed]

Given measurement of voltage and current, which contain gaussian noise with known variance and a constant unknown offset $a_0$, I have attempted to estimate the resistance $R=\frac{V}{I}$. The ...
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2 answers
92 views

Designing of passband and stopband frequencies

good evening guys, let us consider following image we can see from the picture designing of lowpass filter with given passband region and stopband region, only one thing what i am interesting is ...
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30 views

How to generate PSHC carrier used in vocoders

Vocoders are often used to acoustically simulate the information transmitted by a cochlear implant. The different types of vocoders used in cochlear implants include noise-vocoding, sine-vocoding and ...
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1 answer
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Having a hard time understanding FIR filter transverse structures

I'm currently learning about FIR filtering from one of my modules and went through topics such as transverse implementation(or structures since I could not find transverse implementation on the net) ...
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1 vote
2 answers
92 views

Filter coefficients conversion from Matlab for FPGA

Filter in Maltab gives me a set of filter coefficients which I want to use in FPGA/VHDL design. in Matlab I work with floating point, in FPGA I cant use it. Will be it correct if I convert the ...
0 votes
1 answer
36 views

Real parameters design and computation for a filter, modulator

I design in Gaussian filter for a modulator in MATLAB, which should be later implemented in FPGA. I have an implemented design of the filter and the modulator as well and now I have to determine some ...
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0 answers
79 views

How can I generate long time series data of band limited gaussian white noise in Python?

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2 votes
2 answers
65 views

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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0 votes
1 answer
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A real-time (causal, non-symmetric) lowpass FIR filter with minimal passband ripple and phase

I am looking for a lowpass FIR filter that is causal (all samples used are current or past) and exhibits very low passband ripple and has passband phase very close to zero, which necessitates a filter ...
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1 answer
85 views

Formula to compute FIR and IIR Filter coefficients

I am trying to understand filter design. I am trying to implement butterworth filter which would have high,low and bandpass using the difference equation representation for FIR and IIR. Given the low ...
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Particle Filter estimation: sinusoidal signal

I am designing a particle filter for the extraction of a sinusoidal wave with known frequency and sampling frequency from Gaussian noised biased measurements ($y=x+\text{bias}+\text{Noise}$) My state ...
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Question in DSP signal flow graph

How to convert signal flow in Fig3 to Fig4? Is these two equivalent? ZHANG Xiuli, ZHANG Ruihua, CHEN Weidong. Design of digital parametric equalizer based on second-order function[C]// IEEE ...
1 vote
1 answer
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Convert matlab line to scipy signal processing line

I am converting some legacy matlab code to Python and I'm struggling to find the right function in python from the legacy code. The matlab filter is ...
1 vote
2 answers
89 views

Quadrature Mirror Filter symmetry? How to understand this notation

The QMF symmetry of a two-channel filter bank is given by $H_1(z) = H_0(-z)$ I don't understand why such a constraint is quadrature and mirror symmetry. Are $H_1$ and $H_0$ quadrature and mirror ...
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Best way convert transfer function to FIR filter without group delay if i have complex transfer function data

when i calculate acoustic transfer function, system identification using adaptive fir filtering is usually used and that have not tap/2 group delay maybe. in simulation if i have complex number of ...
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2 votes
2 answers
385 views

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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