CxChirpZT

Advanced Analysis Library Only

AnalysisLibErrType CxChirpZT (NIComplexNumber inputSequence[], int numberOfElements, NIComplexNumber startingPoint, NIComplexNumber increment, int algorithm, int numberOfBins, NIComplexNumber transform[]);

Purpose

The Chirp-Z Transform calculates the z transform along a spiral in the z-plane at the following points:

for k = 0, 1, ..., M - 1, where M is numberOfBins, A is startingPoint, and W is increment.

The DIRECT method computes the Chirp-Z Transform as follows:

for k = 0, 1, ..., M - 1.

The DIRECT form can be reformulated with the convolution, as follows:

where . The convolution operation can be performed in the FREQ_DOMAIN method, which uses an FFT-based technique.

Parameters

Input
Name Type Description
inputSequence complex number array The input sequence.
numberOfElements integer The length of inputSequence.
startingPoint complex number The point at which to begin evaluating the Chirp-Z Transform.
increment complex number The increment between each point to evaluate for the Chirp-Z Transform.
algorithm integer The method to use to compute the Chirp-Z Transform. algorithm must be one of the following values:
  • DIRECT (0)
  • FREQ_DOMAIN (1)
numberOfBins integer The length of transform.
Output
Name Type Description
transform complex number array The Chirp-Z Transform of sequence inputSequence.

Return Value

Name Type Description
status AnalysisLibErrType A value that specifies the type of error that occurred. Refer to analysis.h for definitions of these constants.