Questions tagged [filtering]
The filtering tag has no usage guidance.
278
questions
0
votes
3answers
2k views
How to use Kalman filter for altitude prediction based on barometer data?
I have barometer noisy data with known variance.
I studied Kalman filter but I did not find an answer to this problem:
My process model is: altitude is changed because of velocity that is changed ...
1
vote
1answer
319 views
Do integration/differentiation processes work as simple filters?
How these processes are different from simple IIR 1 order filtering, FIR filters in terms of amplitude and phase characteristics?
3
votes
1answer
6k views
Impulse response of ideal filters
I am aware that an ideal low-pass filter in both continuous time and discrete time has a $\mathrm{sinc}$ impulse response. What would the impulse response of an ideal high-pass or band-pass filter ...
1
vote
2answers
909 views
BIBO Stability and the convergence of the frequency response of a system
It is my understanding that an LTI system is BIBO stable if and only if its impulse response $h(t)$ is absolutely integrable. This also happens to be one of the Dirichlet conditions for the ...
0
votes
2answers
536 views
Bandpass filtering IQ samples from USRP
I have an USRP (B205mini) with an RX frequency of 900 MHz and a bandwidth of 100 MHz. I want to distinguish between two raw, unmodulated signals at respectively 875 and 925 MHz.
My approach would be ...
3
votes
2answers
136 views
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 ...
3
votes
1answer
9k views
Apply butterworth filter (lowpass) to a signal
I'm working on a DSP lab and I can't figure out how to apply the filter I've created to a sound. The only thing I found online that did something to my sound was ...
2
votes
3answers
4k views
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 ...
0
votes
1answer
853 views
Extracting the carrier signal from AM
I am new to DSP and leaning about amplitude modulation.
I am trying to demodulate a 5 Hz signal that is modulated by a 50 Hz carrier. I am trying to extract the carrier, not the the 5 Hz signal.
A ...
1
vote
1answer
287 views
Real-time oscillation-like noise filtering
I am making real-time measurements, which are affected by some noise. This noise has oscillating pattern, i.e. the total signal tends to oscillate around the mean value. The examples of measurements ...
2
votes
0answers
115 views
Use of an impulse-response system to model sediment transport along a river reach
I am new to signal processing and have come into the subject from the study of rivers and basic geophysics. I am trying to test an idea previously put forward that the sediment transport response of ...
0
votes
1answer
749 views
How to eliminate negative frequencies from IQ signal
I have a 192kHz IQ signal from an RF receiver, and i'm trying to remove signals in the negative (or positive) frequency spectrum.
I see that the negative frequency signals are -90 degrees phase ...
1
vote
1answer
135 views
Remove high resolution spurious peaks from sinusoidal signal
I have the current from a LEM transducer measured. The measurement is taken on the output of a transformer. The signal is a 50 Hz signal, measured at 100kHz. When the demand of the system is increased ...
1
vote
0answers
93 views
Processing digital sound in Audiokit to sound like the 1960's
I am looking to imitate 70's analog equipments sound. I was wondering is there a way to create tape saturation / distortion inside Audiokit? I want to add that and randomized tape crackles and ...
1
vote
1answer
5k views
Pre-emphasis filter for speech recognition
I'm trying to design a:
$$H(z)=1 - 0.95z$$
FIR filter, for speech signal. I am using this arm_fir_example_f32.c code shown below. And I need to change the filter ...
4
votes
1answer
935 views
Polyphase Filter decomposition. It is not working
So, I want to do a polyphase implementation of a filter bank (I had problems with it since the beginning and I already asked for help to the community in the past, indeed: Norm MPEG-1 Layer III (Mp3) ...
1
vote
2answers
2k views
Convolution in Spatial Domain Is Multiplication in Frequency Domain
I have to prove convolution in spatial domain is equivalent to multiplication in frequency domain using two matrices.
$$
x(m, n) =
\begin{bmatrix}
1 && 2 \\
3 && 4
\end{bmatrix}
$$
$...
4
votes
2answers
106 views
Filtering without using any transforms
A composite signal is defined as
$$x(t) = \sin(2\pi 10t) + \sin(2\pi 40t) + \sin(2\pi 60t) + \sin(2\pi 50t)$$
Separate the four frequencies without using any of the transform techniques.
0
votes
1answer
1k views
Implementation of the filter function (Matlab) C/C++
I am trying to apply some filtering in C/C++ code, I have designed an algorithm using Matlab and it works well, so now I am moving it to native code.
I am ...
2
votes
2answers
70 views
Recommendation for studying filters
I have a project to do about what happens to a periodic function when we pass it through a low-pass, high-pass and band-pass filter.
I have no expressions for the filters or the function, I just have ...
5
votes
1answer
398 views
Is there a $z$-transform like for variable sampling rate signals?
I'm working with signals with variable sampling rate (the time space between samples is not constant). I know the delay between samples but I don't wont to interpolate the signal.
Is there a way to ...
1
vote
1answer
69 views
position of useful filtered data inside DFT based filtered output
I'm trying to filter a 400 samples signal with various bandstop FIR filters (constant group delay), one at a time to see which one gives me the desired result. Every filter was build using the Kaiser ...
1
vote
3answers
3k views
Laplacian Filter Implementation in MATLAB
I implemented a Laplacian filter for the Lena image, but I get an unexpected output.
For input:
I get output:
I used the mask
...
1
vote
1answer
671 views
Image zoom out using Gaussian blur and downsampling
I am trying to implement a simple zoom out algorithm using two steps:
The image is blurred using gaussian convolution of standard deviation $0.8\sqrt{{\tt zoomfactor}^2-1}$ as we saw in class.
The ...
1
vote
1answer
1k views
How to perform a gaussian blur using FFT?
I am trying to implement a gaussian filter with matlab.Here is my implementation:
So far All I get as output is a black image.
Any hints?
...
0
votes
1answer
53 views
Buffering block and filter length in real-time processing
I have a signal sampled at 256 Hz, which I want to filter with a 50 taps long FIR filter in real time.
Would it be a problem, if my data block size is only 32 samples?
And should I then concatenate 3 ...
0
votes
1answer
446 views
Filter problems in python
I am recording a 30 second 1000Hz Sine wave, saving it to a list, splitting the list into 5 second sublists and I would like to apply a notch filter to each sublist to check when the signal drops out ...
0
votes
2answers
256 views
Filter Implementation
I am rather new to the world of signal processing, and am struggling to understand a fundamental concept: How are filters actually implemented?
I have read a significant portion of this online book, ...
1
vote
0answers
160 views
Electromyography: is this interference from the heart/how to remove it?
I'm using electromyography to evaluate the activity of lumbar erector spinae at various levels of effort.
For this I also intend to sample the activity at complete rest (in prone lying). In my first ...
2
votes
1answer
4k views
homomorphic filter - python overflow
I'm trying to implement the homomorphic filtering as implemented by this research article - step 4 (pdf)
The original Matlab code, which I'm trying to translate into Python, is as follows (WARNING: ...
2
votes
1answer
372 views
Denoising short, non-uniformly spaced, bandlmited sequences
Consider a bandlimited signal $x(t)$ with bandwidth $BW$. Samples of this signal are observed at non-uniformly spaced sample points in the presence of noise:
$y(t_i)=x(t_i) + n_i \qquad i\in\{0,1,\...
1
vote
0answers
38 views
Multitapering in time domain to obtain smoother filtered signals?
Suppose we want to approximate the instantaneous power $z(n) = |y(n)|^2$ of the discrete-time signal $y(n)$, where $y(n)$ is the result of filtering $x(n)$ with a given window $h(n)$, $y(n) = x(n) \...
2
votes
1answer
4k views
Does Higher Sampling Rate Increase SNR?
I have AM demodulated voice samples that come from a 14bit ADC that I will filter, process, and then send to a CODEC. I can choose a sample rate of 96kSPS, 64kSPS, 48kSPS, or 32kSPS at the CODEC. ...
0
votes
0answers
279 views
How to include phase noise in sinusoidal kalman filter model?
I am modelling simple sinusoidal motion using a Kalman filter from the following equation of motion:
$ \ddot{x} = -\omega^2x $
So my matrix equation of motion is:
$$
\begin{bmatrix}
\dot{x} \\
\...
1
vote
2answers
90 views
Tracking unknown number of signals/coordinates
I have a time series data. Where for every time step I have a varying number of object coordinates. I want to track these over time. There might also be some missing coordinates for a few frames. ...
0
votes
1answer
45 views
Is this a robust method for analysing correctness of a filtered signal? Is there a more robust method?
I have a recorded signal which contains several frequency components with stochastic phase and amplitude changes and want to extract the true signal with the other frequency components and noise ...
-2
votes
1answer
827 views
How can i create a low pass filter in matlab
i am trying to create a low pass filter in matlab for a project in signals and systems class but i couldn't. cut off frequency is 500 , sampling frequency is 10000 and the low pass filter's band width ...
2
votes
0answers
40 views
Filtering for Wright-Fisher HMM
I am trying to understand what filter may be suitable for the following HMM:
The signal is a Wright-Fisher one-dimensional diffusion characterised by the SDE
$$dX_{t}=\frac{1}{2}\left(\alpha(1-x)-\...
2
votes
1answer
171 views
Standard deviation is varying with change in amplitude of DC signal
I am trying to make sense of the below code. I am taking a large sample so that I get good estimates for standard deviation.
...
1
vote
0answers
96 views
Fastest way to subtract known music tracks from live videogame audio stream
I want to isolate video game "action" sounds from the video game soundtrack. Given all ~20 songs, I'd like to filter them out from any live audio stream during gameplay.
What is a fast and robust way ...
1
vote
1answer
8k views
Differences between low-pass, band-pass, notch filters
I'm studying image processing and I know that there are different filters you can apply. I don't understand the difference between the low-pass/bandpass/notch filter (or high-pass/band-reject/notch). ...
4
votes
1answer
8k views
Simple software low pass filter
I am measuring voltages and currents of a 3-phase electrical machine and I need to calculate the power. Every interrupt (frequency between 30-70kHz) I get values (voltages, currents) from analogue-...
0
votes
1answer
336 views
Relative Computational Complexity for Channelizer Implementations
Suppose I want to separate a broadband input signal into multiple narrow subbands using an FFT-based analysis filter bank. The filter bank uses a prototype lowpass filter and is implemented using a ...
1
vote
1answer
107 views
Filter results from force measurements
I was provided with several force measurements. Precisely:
The vertical compression force exerted from the milling tool on a working peace. The plot of the force looks reasonable and of course it ...
5
votes
4answers
2k views
Does a filter add oscillations to a signal?
this is a more general version of a question which i asked previously.
From what I understand, the purpose of a filter is to change the amplitude of a specific frequency band.
As I went through the ...
0
votes
1answer
357 views
How to find analytic description of filtered signal
I am looking for an exact analytic description of a filtered signal. I have an electronic circuit whose input is a monoexponential decay. First (1) the signal gets filtered by a simple RC-Lowpass. ...
1
vote
2answers
4k views
How to apply low-pass filter to an I/Q signal to get baseband signal?
Can anyone help me with the demodulation technique of a modulated signal? I mixed it with I/Q signal. But I am very confused about low-pass filtering. I am trying to apply a low-pass filter, but I am ...
0
votes
1answer
759 views
Digital Lowpass butterworth filter with cut off 500Hz and sampling rate 1.25MSPS
I am trying to simulate a distributed sensing system and I need to filter only frequencies lesser than 500 Hz(low pass filter) from acquired signal with sample rate 1250000 Samples/sec using below ...
7
votes
1answer
1k views
Adaptive filtering: Optimum filter length and delay
I'm trying to find the optimum filter length for an Adaptive Filtering, using RLS Algorithm.
I'm using this design:
So the "error" signal is the signal without noise (and that's the signal that I ...
0
votes
2answers
4k views
preprocessing raw ECG data
I need to preprocess raw ecg data in R, here is a sample already standardized. I'm not an expert in signal processing nor experienced in working with medical data, so I need concrete answers ideally ...
