Campbell Scientific CR5000 Measurement and Control Module - Manual (Page 106)

Section 6. Data Table Declarations and Output Processing Instructions
6-12
where n is the number of values processed over the output interval and X
i
and Y
i
are the individual values of X and Y .
Parameter&
Data Type Enter
NumVals
Constant The number of elements in the array to include in the covariance calculations
Source
Variable
Array The variable array that contains the values from which to calculate the
covariances. If the covariance calculations are to start at some element of the
array later than the first, be sure to include the element number in the source
(e.g., X(3)).
DataType A code to select the data storage format.
Constant Alpha Code Numeric Code Data Format
IEEE4 24 IEEE 4 byte floating point
FP2 7 Campbell Scientific 2 byte floating point
DisableVar
Constant,
A non-zero value will disable intermediate processing. When the disable variable is
≠
0
the current input is not included in the Covariance.
Variable, or Value Result
Expression 0 Process current input
≠
0 Do not process current input
NumCov
Constant The number of covariances to calculate. The maximum number of covariances is
Z/2*(Z+1). Where Z= NumVals. If X(1) is the first specified element of the
source array, the covariances are calculated and output in the following
sequence: X_Cov(1)…X_Cov(Z/2*(Z+1)) = Cov[X(1),X(1)], Cov[X(1),X(2)],
Cov[X(1),X(3)], … Cov[X(1),X(Z)], Cov[X(2),X(2)], Cov[X(2),X(3)], …
Cov[X(2),X(Z)], … Cov[X(Z),X(Z)]. The first “ NumCov” of these possible
covariances are output.
FFT (Source, DataType, N, Tau, Units, Option)
The FFT performs a Fast Fourier Transform on a time series of measurements
stored in an array. It can also perform an inverse FFT, generating a time series
from the results of an FFT. Depending on the output option chosen, the output
can be: 0) The real and imaginary parts of the FFT; 1) Amplitude spectrum.
2) Amplitude and Phase Spectrum; 3) Power Spectrum; 4) Power Spectral
Density (PSD); or 5) Inverse FFT.
Parameter
& Data Type Enter
Source
Variable
The name of the Variable array that contains the input data for the FFT.
DataType A code to select the data storage format.
Constant Alpha Code Numeric Code Data Format
IEEE4 24 IEEE 4 byte floating point
FP2 7 Campbell Scientific 2 byte floating point
N
Constant
Number of points in the original time series. The number of points must be a power of 2
(i.e., 512, 1024, 2048, etc.).
Tau
Constant
The sampling interval of the time series.