# All Questions

4 views

### On impulse response modeling in acoustics

Why is all pole model pretty useful in modeling room acoustics? Is it related to reverberation?
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 ...
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 ...
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 ...
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. ...
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 ...
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 ...
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. ...
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 ...
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 ...
9 views

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 ...
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 ...
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 ...