I am trying to find out the time delay between two signals using crosscorrelation.

Hi The sampling rate of my data is 30 milliseconds. If hd and pd are my two time series data, I use

crosscorr (hd,pd)

to compute crosscorrelation. and

D = finddelay (hd,pd)

Now the value of D is -2. What do I infer from it ?? How much is the time delay ??

Answer 1

[Pham Dang]

First paragraph of

 help finddelay

ends by : If Y is delayed with respect to X, D is positive. If Y is advanced with respect to X, D is negative.

Therefore your sequence pd is advanced by 2 samples with respect to hd.

The delay (in time) is equal to the number of samples multiplied by the sampling period.

(By the way, the unit of measurement of a sampling rate is "samples/seconds" or "Hz" and not "seconds" ; therefore, did you give the sampling "rate" or the sampling "period" ?)

[Add]

What I have given is the sampling rate of the data. But by mistake I wrote it in milliseconds. The sampling rate is 30 seconds . What is my sampling period here in this case??

[Pham Dang]

Please read the definition of sampling rate and sampling period : Sampling (signal processing)