# All Questions

7 views

### problems calculating phase propagation (in C)

I'm coding a phase vocoder in C for time-stretching audio signals. The only piece that is currently not working is the phase propagation. I take overlapping frames from an input signal, apply a ...
8 views

### How to undo the quantization step in DCT?

How can I do point by point multiplication of the quantized DCT coefficients with the quantization matrix before computing the inverse DCT for each block? I want to modify the reconstruction algorithm ...
11 views

### given a mixture of two signals, how to separate it to its base components?

I have a signal that contains two components. How can I separate it two its two components in matlab?
10 views

### JPEG Compression and DCT

What is the relationship between the 8-by-8 blocks of the image and their corresponding DCT coefficients?
10 views

### stochastic signal and speesdster

I am using speedster to make a mdl model, which consist of (1) different blocks that are noisy signal generator, (2) a CCF(cross correlation function) as signal analyzer, and (3) also a hold time plot ...
15 views

### How to unify the color and brightness measure of two given camera?

I have two cameras, and I'm up to perform some matching stuff on videos captured by these two cameras since I'm a CV guy. The problem is the two cameras have very different performance in terms of ...
15 views

### DPD auto and crosscorrelation

I am trying to learn signal processing and digital pre-distortion. http://www.altera.com/end-markets/wireless/advanced-dsp/predistortion/wir-digital-predistortion.html I am currently trying to auto ...
27 views

### Matlab HIgh frequency sine wave generation

I need to generated a high frequency sinusoidal signal for modulation in MATLAB. But it turns out to be something weird. This is the simple code snippet I used... ...
28 views

### Time delay estimate and sampling frequency

This is an extention to my other question. My sampling frequency is only about 2x my tone frequency. I want to estimate time delay of arrival using this signal. I am generating the tone signal so I ...
45 views

### Measure the SNR of a signal in the frequency domain?

How do you measure the SNR of a sinewave in the frequency domain? Suppose: $$x(n) = s(n) + n(n)$$ Create the signal (nCycles of a sinewave) in MATLAB...: ...
28 views

### How is compression ratio related to number of dct coefficients

Lets say we have a picture with 6bits/pixel and we use discrete cosine transform with 8x8 blocks of pixels and each coefficient is 8 bits. We can use 2 8x8 masks, a zonal mask A and a zonal bit ...
26 views

### Power spectral density interpretation

After reading this question: PSD (Power spectral density) explanation I am still a little confused as to what extra information the PSD gives us over simply taking the magnitude of the fourier ...
46 views

### Fourier Transform for frequency analysis

I applied Fourier transform on a sound (PCM generated digitally with sin function) and frequency detection is accurate. However, if I play the sound and record it, and then apply a Fourier transform ...
47 views

### Which kernel produces sharper image

kernel A = [ 0 -1 0 -1 4 -1 0 -1 0 ] and B = [-1 0 -1 0 4 0 -1 0 -1 ] i have found the frequency spectrums with ...
12 views

### Any ADC for 100Ksps to 10Msps? [on hold]

I have to sample 50kHz signals having BW of ~30Khz (35KHz-65KHz). For this purpose I'm looking for ADC's with 1. Variable clock rate/flexible clock input 2. Dual channel (14bit) 3. Sampling rate ...
34 views

### GLOBAL THRESHOLDING using histogram

There is a recursive way of finding threshold in the image using histogram that are biomodal, and is as follows: An automated procedure for bimodal histograms : Select an initial estimate of T ...
22 views

### how to process audio files in Matlab

I have project in which I'll work on audio files using Matlab, I'll be listing to different machine and should get thei rotational speeds, which is kind of periodic, my question how should I analyse ...
20 views

### Convolve a minimum phase wavelet with delta peak

let's assume I have two time series: one with a delta peak at position $x$ and another time series with a minimum phase wavelet that starts at time $y$ with a maximum peak at position $z$. Now, when ...
46 views

### problem with Fourier transform

I am reading some paper, and I am having some trouble with some Fourier transform, Suppose that $F(\omega)$ is the Fourier transform of $f(x)$, i.e. where ...
30 views

### QAM for analog and digital waves

I tried the following code for modulation of two analog waves. Can anyone point to how to modulate and demodulate for an analog and a digital wave? I tried by replacing the second signal (x2) with a ...
19 views

### NxM DCT matrix generation

How can I generate an NxM DCT matrix? In Matlab dctmtx function generates only square matrix (NxN).
23 views

### Entropy as an objective function for optimization

Background Information : http://mathworld.wolfram.com/KolmogorovEntropy.html Kolmogorov entropy is calculated by delay embedding a 1 dimensional time series into higher dimension using Takens ...
19 views

### KNN match for object recognition

d1/d2<0.6 gives a large number of false matches and it assumes the nearest neighbor is the correct match. Anybody knows any good method to reduce number of false matches or filter them ? Can we ...
240 views

### How to compare audio signals

I want to create a project that will recognized the chords that i played in guitar. I recorded a raw sound to be compare to the one that the user will input. Example I have a recorded sound chordA ...
66 views

### FFT plot in Matlab, accuracy

I have a small input signal of 60Hz sine wave from signal generator, which is corrupted with 50Hz mains supply frequency. I want to measure the amplitude of the 60Hz signal using FFT because it is ...
22 views

### Inverted values - digital resolution issue?

first of all, I am not a technician, but I would really appreciate your helping with one (I hope simple or trivial) issue. I recorded a signal (skin conductance level - SCL, uS unit) with my device - ...
18 views

### Yule Walker Power Spectral density matching

I've written the codes to give psd for spoken digits... e.g. 1,2,3 etc. Now, I want to compare the YW psd (given by pyulear(signal,12,512,22050)) of the test pattern with one of the yw psd patterns ...
47 views

### Is there a closed form expression for main-lobe width increase given a window?

We know that when we window a signal, we increase the main-lobe width. Let 'main-lobe-width' here be the null-to-null bandwidth of the main lobe. Let us further more say that the main-lobe width of a ...
37 views

### FFT of complex envelope

I have I and Q samples of a time domain signal, sampled at a rate T, both of length L. I create the complex envelope, C = sampleI+j*sampleQ. Then take the FFT of ...
60 views

### dsp processor in mobile phones [on hold]

Does a smartphone have a dedicated Digital signal processor? if it does, which company produces dsp processors for mobile applications if not, how does the smartphone manage analog voice and other ...
19 views

### select meaningful part out of a signal (for goertzel)

I have an on going input signal, most of the time with no activity. Once in a while there is an activity (oscillations in different freq). I need to take good 205 samples out of the signal. what i ...
52 views

### SPL values from FFT of microphone signal

I am trying to get a frequency response vs dB SPL plot for recorded sounds. I have a microphone with a flat response, a sensitivity of 4mV/Pa, and 1 Pa = 94dB. To get the dB SPL, I have the following ...
164 views

### What's the Model for a DAC followed by a sampler

I have a situation where a sampled signal is passed through a DAC and re-sampled by a switched capacitor circuit. I can't see a model for this in the literature. The standard model of a DAC is the ...
20 views

### Audio Steganography using Phase Encoding Technique

I referred the below papers to understand the working of Phase Encoding,but the explanation is not proper.Just a few steps have been given in brief. ijcsi.org www.ijarcce.com Can someone please ...
58 views

### Upsampling signal for cross correlation

I am recording a 17khz signal at a sample freq of 44.1khz. I want to perform cross-correlation between the received and transmitted signals for calculating TDOA. But when I do xcorr, the results are ...
34 views

### can't get the right spectrum in scilab

I'm trying to write a simple script that should plot the spectrum in scilab, to test it I use a sinus function with 440hz so that I get my dirac in this position , my problem is that it doesn't work ...
23 views

### filtering fft spectrum further?

I am working on bearing faults.I did the high pass filter and then calculated the envelope of the signal in the time domain. I then found its fourier. The fft spectrum is still not clear. My ...
61 views

### How can I use time-series transforms for detecting malware?

I am student of network security, and very unfamiliar with the domain of signal processing. Do pardon my naivety at asking very basic stuff. My work deals with detecting malicious activity in network ...
18 views

### Power spectral density plot using welch's periodogram for ofdm in matlab

I tried to reproduce one paper about ofdm, which is dealing with out-of band power issues in ofdm. In that, they used 1680 subcarriers. (IEEE 802.22 standard), and welch's average periodogram method ...
16 views

### Confusion regarding Dimension of AR model

I have a confusion regarding what is meant by dimension of AR,ARMA,MA model? Considering an AR model $x(t) = a1*x(t-1) + a2*x(t-2)$ is a 2 order AR model with $a1,a2$ as the parameters. This equation ...
9 views

### Relationship between phase space volume and entropy minimization

I would like to know if there is any analytical proof or relationship which can show that for a dynamical system in presence of chaos signal, if the phase space volume (PSV) minimization leads to the ...
24 views

### Is there an analogue of coherence between data sets related by a non-linear transformation?

Calculating the coherence (sometimes called magnitude squared coherence) between two signals indicates the presence or lack thereof of a linear transformation between the two signals. Is there an ...
18 views

### Finding Signal Energy of a continuous signal in the time domain

I have a quick concern regarding an assignment that I'm working on. Currently, to find the signal energy of a continuous signal, we're converting the signal to the frequency domain through a fourier ...
24 views

### EEG signal processing

I'm working on EEG data to analyse alpha and beta frequencies only. After applying ButterWorth bandpass filter to the signal,I want to apply energy spectral density(ESD) to analyse the signal. How to ...
26 views

### How to obtain the Spectrogram of a signal

I am trying to use Matlab to compute the spectrogram of a signal but I can't seem to figure out how Matlab computes the spectrogram.Consider the case where I have a ...
14 views

### find area of all triangles from Output of delaunay triangulation

I am detecting roadline pattern in an image. I have applied delaunay triangulation. i get 160 triangles in that. Now i need to find the area for each triangle. Can kindly help me. Only after this i ...
26 views

### Decode audio files from magnetic tapes (Raw Files)

I have exported some raw data out of a DDS-4 magnetic tape using the dd command. Apparently the tape stores thousands of audio files encoded in U-law or A-law G711 or G729. I would like to know which ...
34 views

### Explanation of binning in frequency analysis post-FFT

I am creating an Android app which records sound for t seconds at a sampling rate of 44.1kHz with a buffer size of 8192 (16 bit mono samples). I need to plot a ...