National Instruments 320571-01 用户手册

Computes the convolution of the input
sequences X and Y.  The convolution Cxy(t), of
the signals x(t) and y(t), is defined as follows:

Cxy(t)  =  x(t) * y(t)  =

∫

-

∞

∞

 x(

τ

) y(t-

τ

)  d

τ

 ,

where the symbol * denotes convolution.

For the discrete implementation of the convolution, let Cxy 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.  Assuming that indexed
elements of X and Y that lie outside their range are zero,

x

i

  =  0,

i < 0   or   i 

≥

 n

and

y

j

  

=  0,

j < 0   or   j 

≥

 m,

then you obtain the elements of Cxy using:

Cxyi

 

= 

∑

k = 0

n-

1

 x

k 

yi

-k

for  i = 0, 1, 2, …, size-1 ,

size = n + m - 1,

where size is the total number of elements in the output sequence X * Y.

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.

Cxy in is a DSP Handle Cluster that indicates the memory buffer on the DSP board that will contain the
convolution of X with Y.

Note: The size of Cxy in must be (n+m-1) elements long.  n is the size of X, m is the size of Y.  You

cannot perform the operation in place.

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

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.