National Instruments Car Stereo System 320571-01 用户手册

Computes the cross correlation of the input
sequences X and Y.  The cross correlation R

xy

(t)

of the signals x(t) and y(t) is defined as follows:

R

xy

(t)  =  x(t) 

⊗

 y(t)  =

∫

-

∞

∞

 x(

t

) y(t+

t

) 

d

t

 ,

where the symbol 

⊗

 denotes correlation.

For the discrete implementation of the correlation, let R

xy 

 represent the output sequence X 

⊗

 Y, n be the number of

elements in the input sequence X, and m be the number of elements in the input sequence Y.  You  then obtain the
elements of R

xy 

 using the following formula:

R

xy 

i

 

 = 

∑

k=0

n-1

 x[k] y[k+m-1]

for  i = 0, 1, 2, …,  m+n-1 ,

X is a DSP Handle Cluster that indicates the memory buffer on the DSP board that contains the input
signal array X.

Y is a DSP Handle Cluster that indicates the memory buffer on the DSP board that contains the input
signal array Y.

Rxy in is a DSP Handle Cluster that indicates the memory buffer on the DSP board that will contain the
correlation results.

Note: The size of Rxy in must be at least (n+m-1) elements long.  n is the size of X, m is the size

of Y.

Rxy out is a DSP Handle Cluster that is identical to the Rxy in, but with the correlation of X and Y
already stored in the memory buffer on the DSP board.

Note: If X and Y are the same array, an auto correlation is performed, otherwise, a cross correlation is

performed.  You cannot perform the operation in place.

error in (no error) contains the error information from a previous VI.  If an error occurs, it is passed out
error out and no other calls are made.

error out contains the error information for this call.