## Forums Search for: Cross Correlation

## Calculating cross-correlation from two auto-correlations

inHello, I have two autocorrelation sequences of unknown signals A and B, and I need to calculate cross-correlation between these two. Is there...

Hello, I have two autocorrelation sequences of unknown signals A and B, and I need to calculate cross-correlation between these two. Is there any way to do that without performing spectral factorization? Thanks in advance. Tony

## cross correlation

Hello, My name is maz and I am working on simple sound source localization. My question is how do I calculate the delay between these two sound...

Hello, My name is maz and I am working on simple sound source localization. My question is how do I calculate the delay between these two sound signals using cross-correlation in matlab. (I am not considering sound for the start as i have taken the readings in a sound free environment). I do not know since I am still learning. Can you please explain with the help of the matlab code. Thank you.

## cross correlation sound

inHello, My name is maz and I am working on simple sound source localization. I have to find the location of a sound source on a 2d plane. (I am...

Hello, My name is maz and I am working on simple sound source localization. I have to find the location of a sound source on a 2d plane. (I am not considering z axis). I have 4 mics placed on a wooden platform, the co-ordinates of which are m1(0,0), m2(0,6), m3(4,6), m4(4,0). del12 is the difference between the distance from mic 1 to the source and from mic 2 to the source. del12=(delay betw...

## FFT

inHi, I am working on calculating the delay between the 2 sound sources arrived on the microphones. The sound sources are not exactly the same...

Hi, I am working on calculating the delay between the 2 sound sources arrived on the microphones. The sound sources are not exactly the same due to the various factors. I have tried cross - correlation but I have unsuccessful. I have heard about frequency cross-correlation using FFT for determining the delay. How do I do that in MATLAB? Can someone please explain with the help of an example cod...

## Resolution problem in cross correlation process

inHello, I want to detect the phase shift between two sinusoidal signals (have same frequencies) by investigating the cross correlation of them...

Hello, I want to detect the phase shift between two sinusoidal signals (have same frequencies) by investigating the cross correlation of them (xcorr in Matlab). But when the sinusoidal signals have low sampling frequencies (but satisfying the Nyquist criteria), the resolution of cross correlation result is very low, which is my problem. Is there any solution to this problem by using the sa...

## GCC

Hello, I have two questions: 1). What is the difference between cross-correlation and generalized cross correlation? 2). In generalized...

Hello, I have two questions: 1). What is the difference between cross-correlation and generalized cross correlation? 2). In generalized cross-correlation why do we use a weighted function? what is the use of it? Thanks, Maz

## Orthogonal Signals Question

inIs the sole criterion for two signals to be orthogonal a cross correlation type relationship? Could two signals that have some frequency...

Is the sole criterion for two signals to be orthogonal a cross correlation type relationship? Could two signals that have some frequency cancellation when added together still be viewed as orthogonal? For example. if x(t) has fourier transform X(f), which has a magnitude of 1 over some BW, B. And y(t) has fourier transform Y(f), has a magnitude of 1 over the same band. If the sole requirem...

## plot of cross correlation of two signals

inHi guys i have the following problem i have two signals x=500*cos(2*pi*fc*t)*rect((t-0.5T)/T) and x1 which is delayed by 0.1 sec fc=1250 ...

Hi guys i have the following problem i have two signals x=500*cos(2*pi*fc*t)*rect((t-0.5T)/T) and x1 which is delayed by 0.1 sec fc=1250 T=40msec and fs=5000Hz i have to plot the correlation Rx1x and i used the following code but the plot ( i have to plot tau in msec) seems that is not right with the theoretical calculations Thanks in advance KS figure(1) form...

## channel estimation in ofdm using preamble

inHi all, In ofdma the preamble is of 2 symbol long first one consist of 4 shorth and then long of some sequence. how do we use second symbol...

Hi all, In ofdma the preamble is of 2 symbol long first one consist of 4 shorth and then long of some sequence. how do we use second symbol preamble (or long preamble) to find the freq response of channel to train equalizer? currently when i do a cross correlation of a preamble received after channel with known sequence of preamble i don't see the frequency response of the channel am i doing...

## What is a mismatched filter?

inHi I'm new to DSP. I'm working on an ultrasonic project which involves measuring the time of flight of a 40khz pulse between 2 transducers....

Hi I'm new to DSP. I'm working on an ultrasonic project which involves measuring the time of flight of a 40khz pulse between 2 transducers. I think I understand how to use cross correlation to slide a stored version of the pulse shape across the received signal until a match is found. This seems to be called matched filtering. I have seen references to a technique called mismatched filtering...

## Cross correlation and resolution

inHi NG, I am not sure if I am violating some DSP rule here.. I should know this, but: I have a time series of 49 samples, which is 49 days...

Hi NG, I am not sure if I am violating some DSP rule here.. I should know this, but: I have a time series of 49 samples, which is 49 days with 1 sample pr. day. I have another 49 sample time series, also with 1 sample pr. day. I would like to cross-correlate these two series to investigate a possible lag, but preferably with a sub-daily resolution. So I resample both time series (simple...

## GCC Clarity.

inI have also tried using the GCC for TDOA estimation. I initially implemented the cross-correlation, but found that even when i changed the angle...

I have also tried using the GCC for TDOA estimation. I initially implemented the cross-correlation, but found that even when i changed the angle of arrival, the delay might not change. This is most definitely wrong, and I suspected that the clarity needed to increase. I implemented the GCC, which does increase the clarity, but just gives back the same value of delay as the standard cross-correlati...

## Generating "Orthogonal" Sequences from a PN sequence

inHi All, PN-sequence and orthogonal sequences (e.g. WH codes) are used for different purposes. I understand that, typically, PN-sequences...

Hi All, PN-sequence and orthogonal sequences (e.g. WH codes) are used for different purposes. I understand that, typically, PN-sequences have low auto-correlation which is good for synchronization but unfortunately have higher cross- correlation bad for multiple access (like in CDMA case) On the other hand, orthogonal sequences have low cross correlation properties (zero in the time s...

## DFT cross correlation

inHi group, I want to implement fast cross correlation using DFT. Therefore, what I do is take two pictures, FT them, complex conjugate one,...

Hi group, I want to implement fast cross correlation using DFT. Therefore, what I do is take two pictures, FT them, complex conjugate one, multiply them and IFT them again. Then, looking at the picture, I should see a peak at a position, which indicates how the two original images are shifted against each other. In theory, it works great (sample pictures with lots of black and very di...

## Microphones position for sound source localization

inHello, I've recently studied some papers about sound source localization method. As I know, 3D sound source localization can be done by Time...

Hello, I've recently studied some papers about sound source localization method. As I know, 3D sound source localization can be done by Time Difference of Arrivals (TDOA) & Generalized Cross Correlation (GCC) methods with four microphones placed on different plane. Its a question about microphone position, how can I place them well for optimization ?! If the environment is a public squar...

## Zero padding FFTed cross correlation

inHello, I try to make a cross correlation when using the FFT to speed up (in contrast to the normal O(n^2) method). First I did not...

Hello, I try to make a cross correlation when using the FFT to speed up (in contrast to the normal O(n^2) method). First I did not zero-pad because changes from the pictures are small. It worked. Then I added zero-padding around my pictures (they are about 600x400 pixels so now with zero-padding they are about 1200x800 pixels). Then all the results are wrong because the images from the dig...

## Again trouble with cross correlation

inHello group, thanks to your help I was able to get my last problem solved (zero padding). Now it works, only small problem is still there:...

Hello group, thanks to your help I was able to get my last problem solved (zero padding). Now it works, only small problem is still there: When my object moves x, y pixels it works when x, y is not too small. For example 10, 7 movement, it works brilliant. But when movement is -1, -1 or -1, 0 or -1, 1 or 0, -1 or 0, 1 or 1, -1 or 1, 0 it always detects a false positive maximum at 0, 0. T...

## ZADOFF-CHU SEQUENCES (in LTE)

inHello, I'm studying Zadoff-Chu sequences properties. If you take a look into "http://en.wikipedia.org/wiki/Zadoff%E2%80%93Chu_sequence" you...

Hello, I'm studying Zadoff-Chu sequences properties. If you take a look into "http://en.wikipedia.org/wiki/Zadoff%E2%80%93Chu_sequence" you can see the generation of the sequence. Well, in LTE (in P-SS) we use 3 sequences of length 63 (N=63) and roots u=25,29,34. All books say that these sequences have an ideal periodic autocorrelation function and a constant periodic cross-correlation equal...

## detection of primary synchronization signal in LTE

Hi All, According to LTE frame structure every frame have primary synchronization signals.And for primary synchronization signal...

Hi All, According to LTE frame structure every frame have primary synchronization signals.And for primary synchronization signal zadoff- chu sequence is used beacuse of its good periodic autocorrelation as well as periodic cross correlation properties. I thought of using noncoherent correlation in time domain.I tried this method in matlab and seems working for me. My problem is it...

## Are there any DSP benefits of choosing a random seed for an MLS?

inTo determine the impulse response of a room, a Maximum Length Sequence (MLS) is produced by a loudspeaker. The room is considered to be a LTI...

To determine the impulse response of a room, a Maximum Length Sequence (MLS) is produced by a loudspeaker. The room is considered to be a LTI system. A microphone is used to capture the output of this linear system. A cross-correlation (or in some texts, a "convolution operation") is then used to determine the impulse response of the room, given that we know the original MLS. In...