What is the difference between cross correlation and persons r correlation for two different signal? What is the difference between cross-correlation and pearsons r correlation for two different signals? It will be very grateful if somebody explains with an example 
 A: Loosely speaking, cross-correlation is a generalization of the Pearson's correlation.  Specifically, when comparing two time series, cross-correlation seeks to obtain a relationship between lags of each series.
For example, assume two time series, $x_t$ and $y_t$, each with $T$ observations.  Also, let $\bar{x}$ and $\bar{y}$ represent the sample means and let $\sigma_x^2$ and $\sigma_y^2$ represent the sample variance. The sample cross-correlation is obtained as follows:
$$\frac{\sum_t^T(x_t-\bar{x})\sum_s^T(y_s-\bar{y})}{\sigma_x\sigma_y}$$ 
Notice the subscripts, with the cross-variance I will compare $x_t$ to lags of $y_{t-s}$ and vice versa.  As a result, with only two series the cross-correlation generates a $T\text{x}T$ matrix (i.e. the above sample cross variance will be entry ($t$,$s$) within the matrix).  Pearson's correlation is actually contained within this cross-correlation matrix, i.e. 
$$\frac{\sum_{t=1}^T(x_t-\bar{x})\sum_{t=1}^T(y_{t}-\bar{y})}{\sigma_x\sigma_y}$$ 
Which will be the first entry of the diagonal.
