Questions tagged [filter-design]
Fiter design is the process of designing a filter.
1,130
questions
1
vote
1
answer
63
views
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 ...
- 13
2
votes
1
answer
47
views
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 ...
- 175
5
votes
1
answer
213
views
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 ...
- 175
1
vote
0
answers
16
views
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 ...
- 5,818
0
votes
0
answers
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 ...
- 1
1
vote
0
answers
65
views
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 ...
- 115
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 ...
- 141
0
votes
0
answers
86
views
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 ...
- 1
0
votes
0
answers
82
views
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 ...
- 1
0
votes
1
answer
75
views
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 ...
- 418
0
votes
2
answers
35
views
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 ...
- 1
1
vote
2
answers
51
views
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:
...
- 232
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 ...
- 43
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 ...
- 199
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:
...
- 417
1
vote
1
answer
35
views
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
...
- 417
0
votes
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 ...
- 3
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) ...
- 133
1
vote
1
answer
88
views
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 ...
- 570
0
votes
0
answers
49
views
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 ...
- 25
2
votes
1
answer
84
views
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 ...
- 417
0
votes
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 ...
- 25
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
17
views
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, "...
- 125
2
votes
1
answer
42
views
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?
...
- 21
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 ...
- 386
1
vote
1
answer
34
views
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 ...
0
votes
0
answers
69
views
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 ...
- 1
0
votes
0
answers
26
views
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 ...
- 199
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 ...
- 111
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 ...
- 909
0
votes
1
answer
26
views
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 ...
- 931
0
votes
0
answers
21
views
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 ...
- 359
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 ...
- 41
0
votes
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 ...
user350
0
votes
0
answers
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 ...
- 93
0
votes
1
answer
35
views
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) ...
- 103
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 ...
- 357
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 ...
- 357
0
votes
0
answers
79
views
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 ...
- 43
0
votes
1
answer
44
views
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 ...
- 65
0
votes
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 ...
- 41
0
votes
0
answers
25
views
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 ...
- 41
0
votes
0
answers
27
views
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
58
views
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
...
- 11
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 ...
- 279
0
votes
1
answer
46
views
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 ...
- 81
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 ...
- 43