All Questions

3 views

Fixed-length training data from variable-length signals for dictionary learning

My question relates to the topic of dictionary learning for 1-D signal classification. In a nutshell, I have a training dataset of N signals that belong to one of two classes, and I want to find a ...
4 views

Histogram Intersection with two different bin sizes?

I have two images: A and B. Image A is a screenshot of image B, the original image. While there is noise in image A, the original features are still distinguishable. Histogram intersection tells us ...
32 views

FFT on XY data points

Are there any algorithms out there that can do a FFT of 2D or XY data (not sure of the exact terminology here), I don't mean XY data like in a graph I mean XY/2D data points like a circle or a smiley ...
22 views

time frequency localization using wavelet transform

I am currently doing analysis on Photoplethysmograph (PPG) data and I want to know the frequency (heart rate) at every time point so a windowed FFT might not be the best option. I am looking at ...
16 views

Filtering and decimating input as sections in multiple stages

What would be my options to decimate a large input signal available only in sections (or blocks) due to DMA type of interface? The FIR should be about order of 18 only and the total decimation factor ...
20 views

Wavelet transform in control systems

In control systems, the Laplace transform is often used to analyze the stability and the performance of LTI system. For instance, the LTI system is stable if and only if the transfer function, which ...
41 views

Rendering a spectrogram of audio data - resulting magnitudes are all too close together

I'm working on creating an application which will render a spectrogram of the audio in an MP3 file. I'm having some trouble, though - after running the audio samples through my program, the resulting ...
9 views

Is possible to perform algebric operation with bitwise operations in PDM domain?

I have to compute the some operations (say sum and subtraction) between 2 signals. I have data in PDM domain: x1_pdm(t)=[0101011....]; and x2_pdm(t)=[0101011....]; What I do now is: convert x1_pdm and ...
33 views

phase angle of harmonic

I have generated sinsuoids containing fundamental with harmonics using C++. Fundamental frequency is 50 Hz and each of the harmonic has phase offset of 60 degrees. I have applied flattop window before ...
14 views

How to handle encoder wraparound in an alpha-beta filter

I want to use an alpha beta filter to estimate speed from an encoder that's mounted on a motor shaft. The encoder position wraps around to zero every 8192 counts; it gives the absolute angle of the ...
35 views

Simple fft to Gaussian pulse with MATLAB

trying simply to create femtosecond pulse in MATLAB exactly like in the attached image, the carrier frequency is around 374THz, and my sampling frequency is 10 times the carrier. The results of ...
38 views

upsampling by huge factor

Assume i have a discrete signal, which i want to up-sample by factor 100. Up-sampling using poly-phase algorithm sounds like a bad idea, in terms of cache low-efficiency due to low space-locality of ...
30 views

Incorrect Frequency results when using Multiple Signal Classification (MUSIC)

I am using MUSIC (Multiple Signal Classification) to determine Direction Of Arrival (DOA) and frequency of signals impinging on an Antenna Array. I am using a function ...
27 views

Interpreting magnitude of DFT results

I'm working on creating a simple program to render spectrograms like this one. In this plot, the X-axis is time, the Y-axis is frequency, and the color represents the magnitude of the DFT at that ...
35 views

Which is the best method for feature extraction of sclera image? [duplicate]

I have segmented sclera from am eye image.Now i have to extract the feature of the sclera for my thesis of sclera recognition. Which method is best for feature extraction? Please give some sample ...
54 views

Reconstruct FIR frequency response from the coefficients

There is a lot of tools for designing FIR filters. Using one such tool I have designed a filter that satisfies my needs. It's coefficients are as follows: ...
20 views

Image Segmentation applications

I wanna experiment k-means clustering method on different kind of images, so I am trying to find different kind of images used in image segmentation such as MRI images.I want to gather some more ...
16 views

how to compute the power spectral density matrix of the signal

I am implementing in Matlab a paper (*) which used the power spectral density matrix of the signal in the initial step. I will sum-up below. Suppose there are M channel measurements, and dividing ...
31 views

Air-coupled microphone

Does anyone know what the heck is a coupled-air microphone? I know that they were used for recording internal body sounds in papers like this and this. I googled the term, but I couldn't find any ...
35 views

Pose estimation of colored checkerboard cubes

I want to find the orientation of 2x2 checkerboard cubes, like these: That is to say, I want to recover their positions and rotations within the image relative to the camera. In my particular ...
60 views

Why does a phase shift in the frequency domain not produce a time delay in the time domain?

Suppose I have an input signal which represents a vehicle front suspension response that has been measured using an accelerometer. It is seen that the measured rear suspension response is effectively ...
17 views

voice mimicking

My wife passed away 5 years ago when my grandson was one. He now has a sister that is 1 1/2. I'd like to find a way to have a children's story read to them in her voice. Is their a way of doing ...
13 views

Issue in partial correlation

For a time series I wanted to plot separately the partial auto correlation. Below is the graph for MA model that I want: This shows plot of two time series of two time series - one is a sequence ...
16 views

Fisheye lens calibration

I am writing a lens correctionion code and the process should do several things: Inverse fisheye projection to obtain rectilinear image Barrel/pincushion correction Vignetting correction Lateral ...
45 views

Autocorrelation and FFT : avoid zero-padding

Some posts evocate the computation of convolution or cross-correlation using FFT and zero-padding the temporal signal. I want to compute the autocorrelation of a 3D array using FFTW (2 dimensions are ...
29 views

Instantaneous power estimation by discrete hilbert transform - how far does it smooth?

In my research area, instantaneous power in a specific frequency band is commonly estimated by the following procedure: Apply a bandpass filter on the raw signal (e.g. 80-90Hz bandpass). Estimate ...
30 views

How to use reshape command for audio processing?

I have applied it: [Y Fs]= wavread('funky.wav'); A = reshape(Y,m,n) but this function is giving errors: Undefined function or variable 'm'. Now how ...
24 views

Where is the energy goes in ANC (Active noise control)?

I just learned there is ANC technology in signal/audio processing domain. By my understanding, if two audio signal, whose phase is diff by 180, added the result will be silent. But from the physical ...
18 views

float image to integer type image

I have a multispectral satellite image and I would like to "transform" each of the image bands into one with integer values. For example to stretch? the image between 0 and 255. Not sure how to ...
34 views

Multiply filter kernel by sine

1)Suppose that we have low-pass filter with cf equal to 0.1. How frequency response would look like if I multiply filter kernel by sine with frequency say 0.3? How this is related to converting ...
47 views

Measuring the similarity of two waveforms [on hold]

I have two approximately sine truncated waveforms of different amplitudes and I want a numerical measure of how similar they are to each other. I am sending a sonic pulse train whose multiple ...
20 views

How to construct Polyphase(Frank) codes in Matlab

I have written a piece of code in Matlab to generate Frank codes - Pastebin link for pulse compression. I know that Frank codes are stepped frequency approximations to Linear Frequency ...
27 views

What are the foremost research areas in modern Statistical Signal Processing? [on hold]

I need to know what are some of the most research-demanding areas in today's Statistical Signal processing arena. I know, comprehensive-sensing is one such area? what may be others?
38 views

correct for shift from butterworth filter?

I have implemented a python butterworth filter but it seems to shift the data a lot, the x location of my data is very important to me for my analysis. Is there a way to correct for this shift ...
433 views

why Gaussian noise is usually used?

Gaussian noise with different SNR levels are usually used in research works to simulate a realistic environment. How can researchers guarantee that Gaussian noise can simulate the reality of a System? ...
75 views

what is the unit of SNR?

SNR is defined as: $$SNR=10 \log_{10}\left(\frac{\sigma_s^2}{\sigma_n^2}\right)$$ When we say SNR of 10db is 10 times higher that 20db, it is higher in what? amplitude, power or what? also tell me ...
27 views

How to change the start point of resampling process?

I'm trying to resample a digital communication signal in SciPy or Matlab. Suppose the signal was sampled at 3 samples per second, and I want to resample it to 2 samples per second, the thing is I also ...
17 views

Testing whether instantaneous phase algorithm works 2D

I need to calculate the instantaneous phase $\phi$ of a 2D wave field $U$ in C which can be derived by one of two 1D Hilbert transforms $H$:  q(x,z) = H_1[U(x,z)] = 1/\pi \int_R U(x-\zeta,z) ...
85 views

The reasons for filter explosion

Assume signal $x$, sampled at $f_s = 44100\; \mathrm{Hz}$. I tried to filter it using the Butterworth bandpass filter ( $30\; \mathrm{Hz} - 70\; \mathrm{Hz}$) of order $8$. However, as a result I get ...
23 views

comb filter - attenuation

I have a signal and from 'standard information' I know the predominant frequency is at 1Hz and then there should be three harmonics at lower amplitudes. My signal however has a lower amplitude at 1Hz, ...
33 views

variable length no-refrence filter algorithm

I'm searching for a an algorithm or an idea of implementation. I need to filter a signal in real time, and want to change the length of it (number of taps) in order to change the delay. In low ...
25 views

How can I simulate a broadband ultrasound transducer in Matlab?

I am using a Matlab model to send a broadband acoustic pulse across a fluid. The centre frequency should be 50kHz with 100% bandwidth. It has been suggested that I apply a window the pulse to ...
45 views

map two RGB images in Matlab

I wonder is there any algorithm or method that I can map two RGB images together in Matlab. I mean assume I have following images Is there any way I find what number I should multiply each ...
14 views

How do i get all the information regarding the header of an audio file? [closed]

How do i get some human readable information from an audio file, (most preferably .wav file), like in the form of ascii values, so that i can further write a code to convert the file generated into a ...
45 views

Sampling rate in Wifi 802.11 -> 20 MHz enough with a BW of 20 MHz?

In a Wifi 802.11n context, I'm looking to find the sampling rate to perform some processing on the signal and I've something I cannot understand : in the book Next Generation Wireless LAN's: 802.11n ...
75 views
+50

I used continuous wavelet transform (CWT) to analyze the behavior of a 1-D smooth signal(extracting its modal property, damping and frequency components)in my research. Now someone asked: Why the ...
12 views

Block matching based on correlation method for real time moving object tracking in large frames [closed]

How can we make blocks in the images for block matching? How can calculate correlation value for each blocks between previous and current frame? How can we get maximum correlation value to match the ...
21 views

Do eigenvalues shift with change in SNR

Let $H = \frac{1}{\sqrt{2}}M + \eta$ where $M= \frac{2}{\sqrt{15}}\left( \begin{array}{cccc} 3 & 2 & 1 & 3 \\ 1 & 2 & 3 & 1 \\ 1 & 2 & 1 & 1 \end{array} \right)$ ...