Questions tagged [filtering]
The filtering tag has no usage guidance.
234
questions
1
vote
1answer
96 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 ...
4
votes
4answers
1k 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
333 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
3k 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
585 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
891 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
3k 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 ...
2
votes
2answers
455 views
Optimal Level of Wavelet Decomposition for Denoising
If a certain mother wavelet is defined and the optimal threshold shall be defined via Donoho, how can I define the optimal decomposition level to achieve the best denoising results.
0
votes
1answer
483 views
Analytical expression for step response of digital bessel filter
If I apply a digital Bessel filter to a perfect step function, I get something that looks like the following:
The green line is the input step response data sampled at 500kHz, the red line is ...
1
vote
1answer
473 views
Bandpass filtering an audio signal with MATLAB's $\tt kaiserord$: unknown new frequency component
I am trying to filter an audio signal with kaiserord in MATLAB, but I'm having a problem. Here is my code:
...
0
votes
1answer
165 views
Extracting narrow-band ZigBee signals(4 MHz) from a wide-band WiFi signal(20 MHz)?
I am planning the following.
First sample the 20 MHz WiFi channel (WiFi channel-1 in figure).
Put band pass filters (5 MHz wide) around each of the ZigBee center frequencies (11, 12, 13, 14).
Re-...
2
votes
3answers
871 views
How do I eliminate line noise from USB microphone
I'm trying to record voice from a microphone into my laptop. Unfortunately, the laptop does not have a microphone jack, so I have to use the USB input. This doesn't present a problem when I record ...
1
vote
4answers
252 views
Understanding the lowpass filtering of a digital signal
I do not have any background in Electrical Engineering and I have recently started a project which involves signals captured from sensors.
Lowpass filtering: The way I understand it is: The values ...
2
votes
3answers
147 views
How to filter key clicks?
I am the author of an amateur radio application that produces a waterfall display across a range of frequencies. Time is on the $x$-axis, frequency is on the $y$-axis, and the relative strength of ...
0
votes
1answer
3k views
How do we use signal::filter and signal::butter in R for EEG data?
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 ...
2
votes
1answer
3k views
What is the significance of Butterworth filter in image processing?
Filters like mean,median,gaussian,bilateral and adaptive forms of these filters are used commonly in image processing but not Butterworth filter.
The reasons I could think of are
a) Butterworth ...
1
vote
2answers
143 views
How is Bayesian Estimation related to filtering?
I am reading about estimation theory, including topics like Bayesian Estimation (e.g. Wiener Filtering).
It seems that we usually define a filter in terms of tis frequency response (e.g. High Pass, ...
1
vote
2answers
775 views
Practical examples of ARMA model
I am studying the Kalman filter and its basic implementation, and it was asked to use the filter to estimate a signal observed in noise
$$y(n) = x(n) + v(n)$$
where $v(n) \sim \mathcal{N}(0, \sigma^2)$...
0
votes
0answers
270 views
Prediction-error filter for images
I am interested in studying local pixel value dependencies in images and I am wondering if it exists a general form of prediction-error convolutional filter that is able to suppress the image's ...
3
votes
1answer
547 views
Wiener filter to estimate constant signal
I want to compare the performance of a Wiener Filter and the Kalman filer to estimate the value of a constant $d$ using mesurements corrupted by a white noise. That is, my measurements are of the form
...
2
votes
1answer
2k views
Interpolating/Decimating CIC Filter Group Delay
I have an Interpolating Cascaded Integrator Comb (CIC) filter designed as so:
Rate Change = 100
Number of Stages = 4
Differential Delay = 1
I'd like to calculate ...
2
votes
2answers
138 views
Equalizing frequency response in software
I'm playing audio through a speaker which I know to have a non-flat frequency response, with particularly poor response in the low ($<1\textrm{ kHz}$) ranges. My plan to get around this problem is ...
3
votes
2answers
257 views
Easy way to get rid of noise in a hand drawing
I would like to take a user's hand drawn input, and filter out "noise", aka small sketches or blobs, where the user might have screwed up and accidentally touched his hand to the drawing device, or ...
0
votes
1answer
686 views
Filter and crop an image
I am a big fan of fft convolution. So, I mostly try to avoid non-fft convolution.
Suppose, I am trying to convolute an image with another image. Suppose the first image is $512\times 512$, and, the ...
2
votes
2answers
1k views
Smoothing a staircase
I have some data from a position encoder, so naturally i want to estimate its speed. However, the data is very quantized, so it's difficult to smooth enough to differentiate easily:
Each step level ...
1
vote
0answers
33 views
How do I smooth-over transition from a time-series generated by one system to a time-series generated by another system?
So I have generated a time-series with length on 2N samples, where the first N are generated by one auto-regressive system and the N+1 to 2N are generated by another, similar, auto-regressive system.
...
2
votes
2answers
4k views
Root mean square bandwidth of a signal with flat spectrum
I am trying to derive a simple expression for root-mean-square bandwidth $B_{\rm rms}$ for a signal that has flat spectral density over its entire bandwidth $B$. The expression for the $B_{\rm rms}$ ...
1
vote
2answers
716 views
Convolution to do FIR with initial and final conditions!
I need to apply an FIR filter on chunks of very long signals. I can use MATLAB's filter function as follows to preserve the state of the filter when a new chunk of data is available:
...
1
vote
1answer
252 views
Shock filtering using structure tensor
my name is niladri, I am new to image processing(actually this is my first code). I want to implement shock filter using structure tensor. I have rough idea of what structure tensor is and implemented ...
2
votes
1answer
1k views
Smoothing a power spectrum
My question is regarding how one could/should smooth a rather noisy power spectrum obtained from measurements. There are various methods one can use (a moving average, binning, etc) and I am not sure ...
-1
votes
1answer
117 views
Do filters work on a “per sample basis”?
I'm confused because of filter length, whether (such) filters can be used to filter audio on a "per sample basis"?
By per sample basis I mean that I would like to filter audio one sample at a time, ...
1
vote
2answers
519 views
Undoing a filter operation in MATLAB
Out of curiosity, is it possible to actually reverse a filtering on MATLAB. For example, if I have
...
1
vote
3answers
233 views
Adaptive filter with two inputs
I have general theoretical questions:
Is it true that an adaptive filter with two inputs (one normal and one delayed by the single time increment) can completely get rid of any single frequency ...
1
vote
1answer
808 views
What are the advantages of higher order Kalman Filters like EKF, UKF?
Kalman Filter provides the optimal estimate of the states of a stochastic dynamical system if the system is linear, the measurements are also linear functions of states and the errors in system ...
1
vote
1answer
784 views
Causal and Non-causal filtering. Strange behavior
I'm trying to understand the behavior of a causal filtering exemplified by figure below.
This behavior is making LDA (Linear Discriminant Analysis) misclassify our data, by clearly reverse the signal ...
2
votes
2answers
100 views
What criteria should be used for smoothing
Actually I have some measurement which I want to get rid of noise
I want to use different filter techniques but I am wondering what criteria I should use to check if I am removing noise or not
or if ...
1
vote
1answer
122 views
How can a signal have two maximum frequency components?
$x(t)$ can be exactly reconstructed from its samples at $\omega_s = 10 \textrm{ rad/sec}$. My conclusion is that the maximum frequency component in $x(t)$ is $5\textrm{ rad/sec}$. But I'm being told ...
0
votes
1answer
129 views
A question about sampling theory
Let`s say I have a signal
$m(t)=\cos(4\pi t) + \cos(6\pi t)$
so we can say the signal is containing frequencies $f_1= 2\mathrm{Hz}$ and $f_2= 3\mathrm{Hz}$. The cut-off frequency of the low pass ...
1
vote
1answer
2k views
Choosing correct filter parameters for IMU sensor datas
I have a IMU sensor breakoutboard using ITG3701, LSM303D LinkProduct. This involves accelerometer, gyroscope and magnetometer. I have connected the sensors to a Arduino and sending the datas to ...
0
votes
2answers
134 views
In fourier space, how to apply transfer function with n frequencies to input data with m>>n frequencies
I have a transfer function in Fourier space with $N=2028$ frequencies $(\frac {0, 1}{(N\cdot dx)} \dots ) $
Where $dx = 0.1m$.
I need to apply this transfer function to a signal with 20000 samples (...
0
votes
1answer
131 views
iZotope RX's FFT processing?
How does iZotope RX handle the FFT (i.e. how does it manage to perform those processes in the frequency domain without creating glitches) since its able to e.g.
Apply another DSP process (even time-...
2
votes
2answers
399 views
Filtering Frequency Bands Out of a Signal
Let's say I have a 2 second data set taken at 220Hz sample rate and I would like to filter out the frequency bands associated with the EEG Spectrum:
$$\begin{align}
\Delta:& [1,3]\text{ Hz}\\
\...
2
votes
0answers
83 views
maching convolution filters to results
I am practicing for an exam and I need help in the following question (it is just for me- no grade...)
we get an input image, 6 convolution filters and 6 results.
we need to find the matches between ...
1
vote
0answers
43 views
Proximal operator of image Laplacian
Let $\alpha, \beta > 0$ and $\Delta := \nabla^T \nabla$ be the discrete laplacian operator,
$$\nabla: \mathbb{R}^{n_x \times n_y \times n_z} \rightarrow \mathbb{R}^{3 \times n_x \times n_y \times ...
2
votes
2answers
620 views
Filtering noise from FFT, where noise is known to be shifted delta function
I have an input sequence $x=\{x_1, x_2 , ... x_n\}$ of reals, where $n=2^m$ for some $m$. I wish to calculate FFT of $x$.
$X=FFT(x)$
However, before I calculate the FFT, the signal $x$ gets ...
0
votes
1answer
153 views
Pulse shaping and Baseband filtering
I'm slightly confused about baseband pulse shaping.
Let's assume I have a complex data vector in an arbitrary complex constellation (QAM for example). I would like to pass this complex vector through ...
2
votes
2answers
2k views
How to filter almost periodic noise?
I have signal that looks like this:
As you can see there are some almost periodic pulses at the background with amplitude about 1000. I am saying almost, because, if you zoom in, you may see that ...
2
votes
0answers
143 views
Open source GPS+IMU sensor fusion?
Are there any Open source implementations of GPS+IMU sensor fusion (loosely coupled; i.e. using GPS module output and 9 degree of freedom IMU sensors)? -- kalman filtering based or otherwise
I see a ...
3
votes
4answers
655 views
Removing Bounded Noise from an Audio Signal
I'm currently trying to remove some noise from a "contaminated" audio file. From what's given, I know that the noise is isolated to a specific frequency band - that is, from ~1400 Hz - ~1800 Hz.
The ...
1
vote
2answers
1k views
Median Filter for salt and pepper noise removal
Why median filter is considered as good for removal of salt and pepper noise? What are the other filters used for the same?
