Campbell Scientific CR9000X Measurement and Control System - Manual (Page 286)

Section 7. Measurement Instructions
7-62
FFTSample (Source, DataType)
FFTSample is an output instruction used to sample a variable array written by
an FFTFilt instruction. FFTSample is used in place of the Sample instruction
because it gets the FFT programming from the FFTFilt instruction and stores
this processing information in the header of the data table. Without the
processing information, RTDaq would not be able to automatically detect and
plot the FFT.
Parameter
& Data Type Enter FFTSAMPLE PARAMETERS
Source
Variable
T he variable that in the FFTFilt Destination array that contains the start of the spectrum
returned by the FFTFilt instruction. This must be the same variable array that was used as the
FFTFilt Destination. All of the spectral values returned by the FFTFilt Instruction for that
CR9052 channel will be output. Separate FFTSample instructions are required to output each
of the Reps used in an FFTFilt instruction. The datalogger will return a compile error if it
cannot find an FFTFilt instruction which uses this source variable as the destination for a
spectrum.
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