# filters's questions - English 1answer

1.661 filters questions.

### 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. ...

### removing vertical lines in grayscale images by thickness

Suppose we have a grayscale image that contains vertical lines. Now suppose that not all vertical lines are the same, some of them have different thickness. Question is, is there a way, in MATLAB or ...

### 4 Using convolution as feature extraction?

I am now studying image processing in my spare time. My understanding of convolution is about 'response to a specific filter': When we have a raw image, or raw signal; and a filter, aka kernel; we ...

### kalman filter and pwm sampling frequency [on hold]

0 answers, 11 views filters kalman-filters
can i increase or i change the sampling period of signal reference of PWM indirectly using kalman filter ? please provide me any reference or any other method to do that as soon as possible

### python rewrite lfilter (iir) with for

It's a beginner question, but useful to users from python - signal.lfilter, I was using lfilter from Find reverse one pole ...

### -2 how to apply Time synchronous averaging on a vector not function?

0 answers, 9 views matlab filters time-domain
Mornng; I am working on condition monitoring f gears transmission. I import a database of the current's signal using LMS test lab. and I want to apply TSA (time synchronous averaging ) on this signal. ...

### Explanation of fundamental filtering's consequences on signal

Can anyone explain why exactly an "Overshooting" phenomena is observed when the fundamental harmonic is removed as seen on the figures? Is it technically right to call this "overshooting" at all ? If ...

### 20 What Is the Best First Order IIR (AR Filter) Approximation to a Moving Average Filter (FIR Filter)?

Assume the following first order IIR Filter: $$y[n] = \alpha x[n] + (1 - \alpha) y[n - 1]$$ How can I choose the parameter $\alpha$ s.t. the IIR approximates as good as possible the FIR which is ...

### -1 Find the period in a dataset

0 answers, 18 views fft filters discrete-signals
I have an array of trits... Some are zero, some are one, and most I don't know (yet). In my current data set of the KNOWN bits, currently only 10% are "1". (and only 5% is known). I want to figure ...

### Filtering white noise -> cos function

I have studied convolutions and filters a long time ago. Today, I am trying to review the basics using some notes of mine, but I am finding difficult to solve easy problems. Since I don't have ...

### How do we use signal::filter and signal::butter in R for EEG data?

1 answers, 1.120 views filters signal-analysis filtering bandpass eeg
I am trying to design an experiment to determine the peak amplitude of an EEG signal in response to a stimulus. Till now, our team has been using MATLAB and since we wish to go open source, we are ...

### How to set a Carrier Wave for DBPSK Modulators in gnuradio?

for a Project I need to build an Audio Modem in GNU Radio. I decided, that it would be the best to use DBPSK Modulation, because that is fast and relatively noise resistant. But as it seems, the ...

### 1 Looking for a simple and effective notch filter

1 answers, 122 views filters filter-design
I ran a finite-difference simulation and the behavior of an output signal, $s$, in time, $t$ (sampled with period $\Delta t$) behaves approximately as in the figure below. It is well-described by a ...

### Confused over Stopband attenuation and stopband ripple

1 answers, 32 views matlab filters dsp-core
I have designed this bandstop filter to a desired specification: Stopband attenuation = 40db Passband ripple = 2db etc ... I understand that the stopband ripple can be given by the following: ...

### Bandpass design help

0 answers, 15 views matlab filters dsp-core
I am trying to design a bandstop filter to the following specifications using a basic window hamming. the code used : The results: Hamming gives the following N =3.1/0.06=51.6, therefore a length ...

### 1 How to find out the transfer function of a FIR filter?

1 answers, 320 views filters z-transform transfer-function fir
$$h[n]=\begin{cases}a^n & \text{if } 0 \le n < N \\ 0 & \text{otherwise}\end{cases}$$ And for which values of $a$ the filter is stable I know that the transfer function will be H(z)=\...

### Create a third octave spectrum from a time signal

I have to create a third octave spectrum from a time signal on Octave GNU. I found some code on the net to help me but I don't have all the parts of the algorithm. I have a .csv file which contains ...

### convolve to differentiate black and white colors

1 answers, 107 views matlab filters convolution image correlation
a figure for instance of size 500*500 has half above part with black and below half white should result in a white line where the white meets the black (something like a single line at line 250 with ...

### Python bandpass filter - singular matrix error

1 answers, 512 views filters python bandpass eeg
I've been trying to design a bandpass filter using scipy but I keep getting a LinAlg Singular Matrix error. I read that a singular matrix is one that is not invertable, but I'm not sure how that error ...

### 5 Calculating the SNR of a blurred image

2 answers, 502 views image-processing filters image
I have a blurred and noisy image $X$, I want to apply the Wiener filter on it and get a deblurred and denoised image $Y$ (i.e apply inverse of blurring filter while at the same time reducing some ...

### Stability condition for an iir filter

1 answers, 37 views filters infinite-impulse-response
I have been out of touch with DSP for a while. I was trying to refresh my basics and ended up with this doubt on IIR filter stability condition. I understood that for an iir filter to be stable, the ...

### 1 Matlab: Implement filter with no denominator

2 answers, 51 views matlab filters
A filter like this: $z^{4}\cdot\frac{2 + z^{-1} - 3z^{-3} + ...}{1 - 0.9z^{-1}}$ seems hard for me to implement. The fraction part is easy: ...

### How to best separate my signal into frequency regions?

1 answers, 59 views filters sampling frequency
I have a signal with frequencies betwwen [0.5,500] Hz and i want to create a filter to best separate the signal in the following regions: [0.5-3]Hz [3-8]Hz [8-13]Hz [13-30]Hz [30-500]Hz My ...

### Parameters of Butterworth filter that approximates the amplitude response of a Gaussian filter?

1 answers, 135 views filters filter-design gaussian butterworth
For a given narrowband Gaussian filter with a specific central frequency and filter width, I need corners of a bandpass Butterworth filter whose amplitude response is close enough to the Gaussian ...

### 3 State-Space Representation of Forward and Backward Filters

In [1], the author shows an efficient way of implementing the forward and backward filter using matrices. One can also implement this using filtfilt command in ...

### 3 A basic question about the use of moving average vs low-pass filters in DSP

3 answers, 142 views filters fir
I'm newbie novice in digital signal processing. If one has a signal with some noise superimposed in time series, for which type of information/analysis one would use moving average or LP filter in ...

### 3 Use samples of Fourier transform as DFT?

Consider the LTI system given by: $H(z) = 1 - \frac{1}{2}z^{-1}+\frac{3}{4}z^{-2}$ Let $x[n] = (\frac{1}{2})^nu[n]$ be the input to the system. We want to find the output for $n = 0,1,...,N_a$, using ...

### 1 Least Squares Linear Phase FIR Filter Design

1 answers, 77 views filters filter-design fir least-squares
In explication ''the geometric interpretation of least squares'' Typically, the number of frequency constraints is much greater than the number of design variables (filter coefficients). In these ...

### Convolving with the frequency response of a filter

1 answers, 100 views filters fourier-transform
With scipy I can use signal.butter and signal.lfilter on a time signal. Performing a Fourier ...

### 4 Zero Phase Filter: Determining Initial Conditions for Forward Backward Filtering

Is anybody familiar with Gustafson's algorithm for minimizing transients in forward backward filtering [1]? I'm trying to implement it and my first guess was to check Matlab's filtfilt.m, since they ...

### 1 Question about poles and zeros in AR filter

1 answers, 30 views filters poles-zeros
For AR HP filter zeros, to the right of the imaginary axis poles outside the unit-circle zeros on the real axis poles, to the left of the imaginary axis Apparently, the right answer ...

### Is there anything called uncorrelated filter?

I understand to an extent various filter like low pass filter, high pass filer, Wiener filter Kalman filter etc. I also understand some of this filter will decorrelate/uncorrelate the signal. The ...

### 1 How to plot even and odd parts of log-Gabor filter?

0 answers, 19 views filters gabor
I am reading a paper inwhich there is a plot of log-Gabor quadrature pair which are even and odd. I'm wondering how these two are plotted in time-domain, since log-gabor is real valued in frequency-...

### What Is the Difference Between MRF and Total Variation in Noise Removal?

I have a general question in image processing. I have a noisy image. I would like to classify the noisy image into some regions. Two famous approaches I can use are: MRF/Gibbs MRF: Model the spatial ...

### Implementing FIR/IIR “alike” filter in R

1 answers, 69 views filters filtering r
I am new to signal processing. I am trying to simulate something similar to IIR/FIR filter with $k$ delays to imitate acoustic echo reflection. The difference equations for FIR and IIR respectively ...

### How can a RLS algorithm utilise Wiener filter as FIR (M-tap) block?

I'm currently working with a dataset of $5000$ pulses of $N=15000$ samples each. I managed to implement the RLS algorithms with a FIR M-Tap filter such that $M\leq 15000$ ($150$ seems to achieve the ...

### 1 What is the difference between the sampling frequency of signal and sampling frequency of filter

I believe that there is no connection between the sampling frequency used for converting an analogue filter to digital filter and the one used to sample a signal that the filter will be used on. But I ...

### 3 Mathematical model of equivalent-time sampling, the resulting unevenly spaced periodic signal, and its interpretation

I sample a continuous signal $s(T)$ over time. This leads to $s[t]$, which depends on several factors of which some are (pseudo-) periodic. I am interested in the effect of one such periodic factors ...

### low pass filter in fft

1 answers, 211 views fft filters
I have signal. I do Fast Fourier transform on it and now I have this output. I want to delete the other except two that have high altitude. Can you help me ? My f sample is 2500. My complete time ...

### 2 How do I attenuate a tidal signal in depth time series data

2 answers, 175 views filters c#
I work with depth time series data from electronically tagged fish. When the fish spend time on the bottom we get a prominent tidal signal (approx 1.96 cycles per day). This interferes with our ...

### 1 Short length windowed sinc filter

2 answers, 57 views filters lowpass-filter bandwidth window
I have a 50-60Hz signal being sampled at a frequency of 25 kHz & I'm trying to filter all frequencies beyond 70 Hz with a reasonable steep transition band (approx 4 Hz) & good attenuation (~40+...

### 4 1/3 Octave Analysis

Good Morning! I am new in signal processing and I am trying to do a work in noise control of an electronic steering lock device (ESL). My aim is to calculate the loudness (Zwicker Method- ISO 532 B) ...

### How do I show an impulse response leads to a zero-phase frequency response?

2 answers, 45 views filters impulse-response linear-phase
I'm trying to understand how to show that with real coefficients, the phase response of a filter is 0. Here is the impulse response $h[n] = b_1d[n+1] + b_0d[n] + b_1d[n-1]$ How should I approach ...

### Filtering odd and even frequencies

1 answers, 218 views fft filters