National Instruments Car Stereo System 320571-01 Manual De Usuario
Chapter 2
NI-DSP Analysis VI Reference
NI-DSP SRM for LabVIEW for Windows
2-13
Part 3: NI-DSP Function Reference
DSP Convolution
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:
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,
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.
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.
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.
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.
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 and no other calls are made.
error out contains the error information for this call.