0
votes
0answers
4 views

On impulse response modeling in acoustics

Why is all pole model pretty useful in modeling room acoustics? Is it related to reverberation?
0
votes
0answers
3 views

How to Avoid Perspective Distortion Buildup in a Planar Mosaic

Registering images for map or other planar mosaic from a handheld camera or a drone requires projective transform (homography) as the camera is allowed to rotate between frames. Unfortunately, planar ...
0
votes
0answers
7 views

Problem executing Hilbert transform on x-y plot in MATLAB

I have a wav signal I have imported into MATLAB, and I would like to find its envelope. I want to do this via the Hibert transform. But whenever I try to find the Hilbert transform of the signal I ...
0
votes
1answer
14 views

Power spectrum of a pure sine problems

I am writing a C++ program to use to analyse oscillations and create a power spectrum. I am using FFTW3. To test the system, I am using a perfect sine function. But no matter what parameters I try, I ...
0
votes
0answers
4 views

Intuitive understanding of scale-space extrema detection

Can someone explain intuitively why local maxima and minima in the scale-space domain make for good keypoints? I understand using LoG or DoG zero-crossing points to identify spacial variations, i.e. ...
0
votes
1answer
20 views

Accuracy of sampling rate

I have data corresponding to 300 seconds. Sampling rate is 500Hz. I should have 500*300 = 150000 samples. But due to hardware error, I am receiving a few extra samples. What is the optimal way of ...
0
votes
0answers
8 views

Voice Activity Detection using Spectral Flatness - Can it distinguish voice from a knock of a door?

Spectral flatness is a measure of how much a sound differs from spectrally flat white noise. So, if there is a sample of a voice speaking with relatively high SNR, the Long-Term Spectral Flatness ...
0
votes
0answers
13 views

Problem with image alignment/warping

I am currently working on image alignment. I start with a normal image and then use matlab's imrotate to rotate it 1 degree. Afterwards I calculate my warping matrix and align the image using imwarp. ...
1
vote
0answers
17 views

Event detection in a running person's acceleration data

I am trying to detect some events on this signal : This is the acceleration of someone running. By eyes we can detect many blocs, sometimes separated by a little interval. I would like to be able ...
0
votes
3answers
33 views

Samples of period to frequency, sampling theorem

In the sample rate of 96kHz there are 96000 samples in a second. So a periodic waveform with period 96000 samples has a frequency of 1Hz. A signal with period of 9 samples is ~ 10666 Hz. Of 5 ...
0
votes
0answers
9 views

Matlab: Help in least square estimation of MA model

Let y_n be the noise corrupted output of an FIR channel with known channel order L expressed as $y_n = \sum_{k=0}^{L-1}h_k x_{n-...
2
votes
1answer
25 views

Could there be any reason to prefer convolution-based calculation of autocorrelation?

Theoretically both of ways of calculating autocorrelation function are identical: strightforward convolution and Fourier-based method where we use FFT/iFFT in practice. And as it is well known, the ...
0
votes
1answer
22 views

How does constant frequency response relate to equiripple?

The teacher says As a consquence, you can think of the frequency response of a filter as a shark. It must always move and it can never be rest. An important case is equiripple. I am very confused ...
1
vote
1answer
24 views

What does the frequency axis of a Power Spectral Density mean?

I have never really understood what the frequency axis meant when we plot the Power Spectral Density(PSD). Does it correspond to frequency as we get after we take the Fourier Transform of a time ...
0
votes
0answers
8 views

How to correctly implement spectral activity measure (SAM) for image quality assessement

I am trying to compute the spectral activity measure (SAM) which is a well-known image quality assessment metric. I used MATLAB to implement this method, which can be computed as follows: $$ SAM=\...
0
votes
2answers
20 views

Simulating spatial perception - with cosine wave based sound - in MATLAB

I'm trying to create cosine wave, one for the right channel and another for the left. The one on the left is to be moved in phase to simulate change to the spatial perception of the tone. A delay in ...
0
votes
0answers
9 views

Multitapering with R,memory limitations [on hold]

I am having big problem with R multitaper package.It works fine for small time series,but since I am dealing with geophysical data that are really huge,that I can not use it,at least on my laptop.So I ...
0
votes
1answer
18 views

Modulation of voice

I apologize in advance if the question is very basic. When I google modulation all I read are the techniques that are used to modulate a signal. I start from basic. Let's say I am a reporter and the ...
2
votes
1answer
38 views

Why is the frequency response different based on the amplitude of the impulse I feed into the filter?

I am working on a 2-pole IIR high-pass filter. The filter is fixed point and it is causing me some issues. I believe I'm just misunderstanding something. I am implementing everything in Octave for ...
1
vote
0answers
11 views

Considerations when determining squelch

I asked this question recently. From the comments I learned that squelch is not a hard and fast thing, and that many considerations might go into determining a reasonable value, depending on use, the ...
2
votes
1answer
24 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 ...
0
votes
1answer
16 views

Calculating the perimeter in binary image

After pre-processing, I can obtain the image like this: Then, I want to calculate the perimeter of the bottom region (annotated with grey line). I am making an ImageJ plguin. So I have to implement ...
-2
votes
0answers
12 views

What is the Gaussian Mixture Model (GMM) and why it is used in speaker recognition? [on hold]

My understanding from GMM model in speaker recognition is that first it is trained with some feature vector and then used for the comparing with Test feature vector. Where i will get some material ...
0
votes
0answers
18 views

What are the different ways to compute the DFT? [on hold]

I am new to learning about the DFT. Is there different ways that this can be computed? What are some good resources to learn more about this topic?
1
vote
0answers
26 views

Help in analytical expression in maximum likelihood problem formulation

I have training data $\mathbf{X}$ that consists of $N$ time series as examples where each time series $\{\mathbf{x}_i\}$ is of length $n$. The values of the elements of the times series are binary. ...
0
votes
0answers
26 views

Detecting Song Fade

Can anyone suggest a simple algorithm that would be able to detect when an audio track begins to fade out? The fade duration could be anything from half a second to 30 seconds, totally depending on ...
0
votes
0answers
16 views

Unsupervised parameter estimation : escaping local minima

Let $\{y_n\}$ be the noise corrupted output of an FIR channel with known channel order $L$ expressed as \begin{align} y_n &= \sum_{k=0}^{L-1}h_k b_{n-k} + v_n, \label{Eq1} \end{align} where $b_n$ ...
0
votes
0answers
20 views

How can I remove noise in these strain data? (New to data processing and MatLab)

I am fairly new to data processing and currently was assigned a task to remove noise in these data (strain). Without previous knowledge of data processing and couldn't get much help/guidance out of ...
1
vote
2answers
46 views

Measure similarity between quantized grayscale images

I want to measure the similarity between quantized grayscale images (8 levels) that mostly depict organic patterns found in nature, say pigmentation patterns in animals (zebra pattern, leopard spots,.....
0
votes
1answer
41 views

Anti-Aliasing when oversampled

From a comment in another question I read a statement "In addition, the initial rate of 48kHz is already performing 6 times oversampling and therefore the subsequent decimation by 6 will not ...
0
votes
1answer
13 views

lower-rate LDPC codes

Currently I am using $(128, 64)$ LDPC codes to error correct messages wirelessly sent in Arduino using the SoftwareSerial library. I was advised to use a lower-rate LDPC code and see if that improves ...
0
votes
0answers
24 views

How to normalize $\tt numpy.ifft$ results

I have a function $V_{\rm in}(t) = \cos(t)$ and I've used it to calculate $V_{\rm out}(t)$, now I want to regain $V_{\rm in}$ from $V_{\rm out}$ using $$V_{\rm in}(t)=\mathcal{F}^{-1}\left[\frac{\...
1
vote
2answers
33 views

Detecting which digital number an image represents

I photograph the dashboard of my car every day to register the mileage for work. I use OpenCv to detect the region of the digital displayed mileage, crop to the numbers and match them. The method I ...
0
votes
2answers
47 views

Remove unwanted object of image in MATLAB?

I am trying to remove the unwanted object. I have an image that includes a house and the trees. I am trying to remove the trees. I am using 'imsubtract' to remove small edge. But the result is not ...
0
votes
1answer
16 views

How to acquire physical noise samples

I need to obtain some real (simulated) data to indicate noise in communication system. How do I go about it? I need it for my thesis. I don't know if denoising a set of signals will help so I can ...
0
votes
2answers
18 views

how to detect and capture scene change in a recorded video

I have a project to detect and capture scene change in a recorded video.Actually its a recorded video of a godown (of about 2 weeks) and I have to detect and capture pic whenever someone comes in. I ...
-2
votes
0answers
33 views

How to convert $\rm Hz$ range to $-\pi$ to $\pi$ [on hold]

Suppose you have a periodic signal that has been sampled from $120\textrm{ Hz}$ to $180\textrm{ Hz}$ such that $120\textrm{ Hz}$ is equivalent to $-\pi$ and $180\textrm{ Hz}$ is $+\pi$ How do I go ...
1
vote
1answer
33 views

How to get rid of ripples from a gradient image of a smoothed image?

I have a gray scale uint8 image. When I smooth it with a Gaussian filter and then compute the gradient image with a Sobel filter in OpenCV, ripples would appear. The first image is what happens when ...
0
votes
1answer
31 views

audio recording conversion to decibels(db) [on hold]

I have several audio recording like the crying of a baby, the sound of a moving vehicle etc.How can I convert the audio recording to Decibels (db)value
0
votes
1answer
20 views

Signal sparsity: with noise or without noise?

In compressive-sensing, signal should be sparse. Is this with or without noise? When I differentiate signal, it is supposed to be sparse. But when I add noise on it, it isn't sparse anymore. Should ...
-3
votes
0answers
39 views

How to calculate the Energy/Power of a signal [on hold]

Given a signal $x(t)$ with the definition: $$x(t) = u(t+1)−u(t−1)$$ And considering that a signal is an energy signal if it satisfies the equation: $$ 0 < E_{\infty} = \int_{-\infty}^{\infty}{\...
0
votes
0answers
23 views

How to create and divide a signal envelope? Alternatives welcome

I'm very new to signal processing (still a student) and I'm trying to process a wav file in a certain way. I want to: Create an envelope of the signal (using absolute values of the amplitudes) ...
2
votes
0answers
69 views

Signal rescaling

Please help me out with this one. I think I've been given an impossible task. I'm working on a system that transmits an active signal and looks for strong reflections. The transmitter is actually ...
0
votes
1answer
15 views

Designing observer with non-observable system

I have this state-space system \begin{align} \dot{x}&=\begin{bmatrix}1 & 0\\3 & -2\end{bmatrix}x+\begin{bmatrix}10\\0 \end{bmatrix}u\\ y&=\begin{bmatrix}1 & 0\end{bmatrix}x \end{...
0
votes
0answers
21 views

How to use phase codes for modulating a pulse

I am working on phase codes (examples - Frank, P1, P2, Zadoff Chu) to generate minimum side-lobes on matched filtering. I considered a sinosoidal carrier wave at $45\textrm{ mHz}$, and phase modulated ...
0
votes
0answers
14 views

R, Fourier transform, signal and noise

I have a set of time series data that contains a background noise, one short frequency signal and one occasional signal. I am trying to use R with Fourier transform to separate them and plot these ...
0
votes
0answers
17 views

Sliding windows and crosscorrelation of periodic signal

I am doing cross correlation in MATLAB, and have it working for generalized cross correlation (GCC), and also for GCC-PHAT (GCC with a phase transform weighting function). However, when using a ...
3
votes
3answers
73 views

Why do we use discrete-time sampling?

I have been reading Signals and Systems (2nd ed.) recently. Chapter 7 is about sampling. Oppenheim uses discrete-time signals and continuous-time signals to explain sampling. But why do we need ...
0
votes
0answers
28 views

Undersampling and Phase Light Curve

I have an under sampled data set of a binary star with a 4 hour period. Its been sampled several times per week (yes per week) for 10 years. The resulting data is folded in a Phase diagram, using a ...
1
vote
0answers
30 views

algorithm for segmenting cheese microstructure

I'm trying to get the internal geometry of cheese from images of its microstructure: I tried the canny edge detector and otsu thresholding but neither of these worked very well. I'm guessing that I ...

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