National Instruments 320571-01 用户手册

Computes the Power Spectrum of the
input sequence X.  The Power Spectrum
S

xx

(f) of a function  x(t)  is defined as

S

xx

(f)  =  X

*

(f)X(f)  =  | X(f) | 

2

 ,

where X(f) = F{x(t)}, and X

*

(f)  is the

complex conjugate of X(f).

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

Notes: The number of elements for the input array must be a power of two.

The operation is performed in place and the input array X  is overwritten by the output Power
Spectrum.

The largest power spectrum that can be computed depends upon the amount of memory on your
DSP board.

This VI allocates a temporary workspace on the DSP board equal to the size of the input signal
array.

Power Spectrum is a DSP Handle Cluster that is identical to X, but with the results of Power
Spectrum 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.

Finds the product of the elements of the input
array X.  The product of the elements is
obtained using the following formula:

product  = 

X( i )

i

=

0

n

−

1

∏

where n is the smaller number of elements in X.

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

product is the product of the elements in X.

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.