## long PN sequence' usage in CDMA

Started by in comp.dsp12 years ago

Hi all, there always said long PN sequence(period 2^n-1) got a small cross-correlation property as -1/(2^n-1). But in practice, one...

Hi all, there always said long PN sequence(period 2^n-1) got a small cross-correlation property as -1/(2^n-1). But in practice, one symbol could only be spread by a small amount(128 etc) but not 2^n-1, so how can we guarantee the cross correlation property -1/(2^n-1)? Thanks. B. R. Laron

## long PN sequence' usage in CDMA

Started by in comp.dsp12 years ago 1 reply

Hi all, there always said long PN sequence(period 2^n-1) got a small cross-correlation property as -1/(2^n-1). But in practice, one...

Hi all, there always said long PN sequence(period 2^n-1) got a small cross-correlation property as -1/(2^n-1). But in practice, one symbol could only be spread by a small amount(128 etc) but not 2^n-1, so how can we guarantee the cross correlation property -1/(2^n-1)? Thanks. B. R. Laron

## cross-correlation, chirp finding

Started by in comp.dsp12 years ago 3 replies

I am trying to find short chirps in a signal. I am expecting two repetitions of the chirp. The input signal is sampled at 44.1 Khz and the chirp...

I am trying to find short chirps in a signal. I am expecting two repetitions of the chirp. The input signal is sampled at 44.1 Khz and the chirp is 850 samples long. My current method is to cross-correlate the input signal and the chirp into z. then i use a peak finding algorithm to find the two highest peaks. My current algorithm is messy as the second chirp if it occurs close to the firs...

## matching a reference audio signal in a VoIP environment

Started by in comp.dsp12 years ago 5 replies

hi, i'm trying to match reference audio signals (ranging between 1 sec and 10 seconds) in source audio signal from an RTP stream. i've used...

hi, i'm trying to match reference audio signals (ranging between 1 sec and 10 seconds) in source audio signal from an RTP stream. i've used cross-correlation, which works extremely well (spikes nicely) when there is not much time-altering of the reference audio as it is passed over the RTP stream (i.e., not much packet loss or packet re-ordering, and the local packet-loss-concealment / j...

## basic audio dsp question

Started by in comp.dsp12 years ago 2 replies

I have the following query in relation to Cross-correlation and general Audio DSP signalA is 512 samples @ 44100 samples/sec. length 0.0116...

I have the following query in relation to Cross-correlation and general Audio DSP signalA is 512 samples @ 44100 samples/sec. length 0.0116 seconds I take a recording and play signalA at 0.5 seconds. The recording is 1 second long or 44100 samples @ 44100 samples/sec. When i do a Cross-correlation of signalA and the recording. i plot the result in MatLab and i get the result i was expe...

## Normalised Cross-correlation FFT

Started by in comp.dsp11 years ago 19 replies

Hi, I have implemented cross-correlation using FFT's. Is it possible to to normalised cross-correlation with FFT's? If so, how? Sorry if it...

Hi, I have implemented cross-correlation using FFT's. Is it possible to to normalised cross-correlation with FFT's? If so, how? Sorry if it is a basic question - but I haven't found a solution. Thanks in advance..

## How I can do the Coherence function using AR method

Started by in comp.dsp11 years ago 1 reply

I'm need your help I'm trying to use the coherence function using AR method. But the values obtained are greater than 1. I use the following...

I'm need your help I'm trying to use the coherence function using AR method. But the values obtained are greater than 1. I use the following equation: Cxy=abs(Pxy)^2/Pxx*Pyy where Pxx and Pyy are the obtained with the method AR. Pxy is obtained as follows: first, I use the cross correlation between the two signals. The result is evaluated with AR technique to obtain the Pxy I don't kn...

## Calculating a cross correlation (to find delay) on irregulary sampled data

Started by in comp.dsp11 years ago 3 replies

Hi there, I have two sets of data which are irregularly sampled. These two sets are two measurements of the same product but on different...

Hi there, I have two sets of data which are irregularly sampled. These two sets are two measurements of the same product but on different places. Eg: Sensor 1: time 1, 3, 7, 8, 10, 15 ... Sensor 2: time 1, 2, 3, 5, 9, 10, 11, 14 ... The measurements are irregular because they are done by people, not by an automatic sampled system. I would like to calculate the cross correlation bet...

## Cross correlation via Hartley Transform

Started by in comp.dsp11 years ago 7 replies

Hi ... I am triing to get a cross correlation between two or (later 16) audio channels with the hartley transform (I am doing that in Labview...

Hi ... I am triing to get a cross correlation between two or (later 16) audio channels with the hartley transform (I am doing that in Labview with FFT comparison). But the results don't fit: -> my source: http://rsbweb.nih.gov/nih-image/download/n...docs/thesis.pdf on page 12. So I am doing the Hartley transform on both signals H1(f) and H2(f) ... to get the cross correlation -> iFHT(1/

## Help me with cross correlation, please.

Started by in comp.dsp11 years ago 1 reply

Hi! I'm porting a little Matlab function in C language. My problems raise with xcorr() function. I need to calculate raw correlation...

Hi! I'm porting a little Matlab function in C language. My problems raise with xcorr() function. I need to calculate raw correlation (without normalization) between two vectors. I've found this code http://local.wasp.uwa.edu.au/~pbourke/miscellaneous/correlate/ , but it calculates only a normalized correlation coefficient. However, I've tried to adjust it to calculate a raw correlation vector, ...

## Spread Spectrum system cross correlation

Started by in comp.dsp11 years ago 2 replies

Hi all, Where can I find a practical block diagram of a Direct Sequence Spread Spectrum (DSSS) system? I looked for it everywhere but couldn't...

Hi all, Where can I find a practical block diagram of a Direct Sequence Spread Spectrum (DSSS) system? I looked for it everywhere but couldn't find any. I am aware of the general block diagrams but I am specifically interested in something that shows how the system looks in the real world. Currently, I am trying to implement a DSSS system on Gnuradio. In another question if I am using RRC shap...

## Spread Spectrum system cross correlation

Started by in comp.dsp11 years ago 6 replies

Hi all, Where can I find a practical block diagram of a Direct Sequence Spread Spectrum (DSSS) system? I looked for it everywhere but couldn't...

Hi all, Where can I find a practical block diagram of a Direct Sequence Spread Spectrum (DSSS) system? I looked for it everywhere but couldn't find any. I am aware of the general block diagrams but I am specifically interested in something that shows how the system looks in the real world. Currently, I am trying to implement a DSSS system on Gnuradio. In another question if I am using RRC shap...

## Time delay Measurement via Cross Correlation in DSP board TMS320C6713

Started by in comp.dsp11 years ago 2 replies

I am a new developer in DSP board I am currently working on a project to measure the speed of a small car via Cross correlation in DSP...

I am a new developer in DSP board I am currently working on a project to measure the speed of a small car via Cross correlation in DSP board. This small car has embedded two infrared light sensors which send and receive random signals from the floor. Two random signal are similar except the time delay when the floor reflects the signals. The sensor signals are transmitted to the wireless sende...

## Time delay Measurement via Cross Correlation in DSP board TMS320C6713

Started by in comp.dsp11 years ago

I am a new developer in DSP board I am currently working on a project to measure the speed of a small car via Cross correlation in DSP...

I am a new developer in DSP board I am currently working on a project to measure the speed of a small car via Cross correlation in DSP board. This small car has embedded two infrared light sensors which send and receive random signals from the floor. Two random signal are similar except the time delay when the floor reflects the signals. The sensor signals are transmitted to the wireless sende...

## Cross Correlation Plot

Started by in comp.dsp11 years ago 1 reply

I have to plot the cross correlation Ryx with respect to Doppler shift and Lag in the following code, in a 3D graph using mesh command in Matlab....

I have to plot the cross correlation Ryx with respect to Doppler shift and Lag in the following code, in a 3D graph using mesh command in Matlab. I tried many ways but none of them worked and just gave me errors. Can anyone please guide me? % %Joint estimation of delay and Doppler shift % fd = (-.1:.01:.1)*fp; %Doppler shift range Nd = length(fd); %Number of Doppler shifts K = 4; %interpo...

## Cross correlation in C

Started by in comp.dsp11 years ago 7 replies

Did someone has experience on implementation of cross correlation in C on CCS? I want to realise the cross correlation in frequency domain by...

Did someone has experience on implementation of cross correlation in C on CCS? I want to realise the cross correlation in frequency domain by FFT. Until now the Real time FFT is done. The question is that my input signal is two random signals from two infrared sensors, how random signal is calculated by cross correlation?

## How to implement cross correlation after FFT in DSP?

Started by in comp.dsp11 years ago 1 reply

I have to do cross correlation of two audio file to prove they are similar. I have done FFT of two audio files and have the power spectrum value...

I have to do cross correlation of two audio file to prove they are similar. I have done FFT of two audio files and have the power spectrum value of both the audio file in a separate array.how should i proceed further to do cross correlation to prove they are similar.Any basic ideas will be helpful for me to learn and apply it.Thanks.

## Looking for a fast linear cross correlation implemented in C in C6713

Started by in comp.dsp11 years ago 2 replies

Hi everyone: I am implementing a fast linear correlation in C in DSK C6713. My cross correlation in principle should be implemented as...

Hi everyone: I am implementing a fast linear correlation in C in DSK C6713. My cross correlation in principle should be implemented as following: - two random digital signals from AIC23 codec are the input signals of DSK board. - interrupt intser_McBSP1 is used to input two random signals via two channels(left and right) and output the real part of cross correlation r - Because of the linear f...

## Looking for a fast linear cross correlation implemented in C in C6713

Started by in comp.dsp11 years ago

Hi everyone: I am implementing a fast linear correlation in C in DSK C6713. My cross correlation in principle should be implemented as...

Hi everyone: I am implementing a fast linear correlation in C in DSK C6713. My cross correlation in principle should be implemented as following: - two random digital signals from AIC23 codec are the input signals of DSK board. - interrupt intser_McBSP1 is used to input two random signals via two channels(left and right) and output the real part of cross correlation r - Because of the linear f...

## Similarity measure for signals

Started by in comp.dsp10 years ago 2 replies

Hello, I'm currently working with a new parametric spectral estimation technique (it achieves better resolution frequency than the FFT for...

Hello, I'm currently working with a new parametric spectral estimation technique (it achieves better resolution frequency than the FFT for instance) and I would like to use it so as to find similarities between two or more signals based on their frequency components. I could use the cross correlation or the correlation coefficient but by this way I do not take advantage of the tool that I h...