ChirpZT

Advanced Analysis Library Only

AnalysisLibErrType ChirpZT (double 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 double-precision 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.