Chirp Z-Transform

by
Phuong Tran & Mike Griffin

Children's Hospital Research Foundation
Division of Cardiology
Biomedical Engineering Laboratory
Elland & Bethesda Aves
Cincinnati,Ohio 45229






The Chirp Z-Transform is a computationally efficient
algorithm to compute the z Transform along a spiral contour in
the z domain. If the contour is the unit circle, then this would
be equivalent to computing the Fast Fourier Transform but a
little slower.



System requirements:

IBM-PC w/128k
8087 coprocessor
Hercules Mono Graphics Board

Program Requirements:

This program requires the following files to reside on
the same disk as the program:

4x6.fon
error.msg

Program Description:

The program allows inputs from either the keyboard or a
sequential data file (data is assumed to have both real and
imaginary parts). If a file is specified, it must have a '.DAT'
extension.

The output can be routed to a file,printer or screen. If
the printer or screen is specified, the data points will
be printed from left to right. If a file is specified, it will be
stored on a disk file with a '.DAT' extension.

Regardless of output routing, the magnitude and phase
will be plotted on the screen.

The phase output is plotted from pi/2 to -pi/2.




The input parameters are as follows:

1. Number of complex paired input points
2. Number of complex paired output points
3. Sample rate of the data in Hertz
4. Initial Sigma value of CZT contour in Hertz
5. Initial Omega value of CZT contour in Hertz
6. Increment in Sigma along the CZT contour in Hertz
7. Increment in Omega along the CZT contour in Hertz


Files:

The following files are included in this library:

CHIRPZ.COM - program
4X6.FON - required for graphics
ERROR.MSG - required for graphics
CHIRPZ.DOC - this file
PROCWRIT.PAS - procedure to write data into a file

A version for the color monitor is also available.

Source code is available on request.

References:

1. Programs for Digital Signal Processing
IEEE Press, 1979

2. Theory & Application of Digital Signal Processing
L.R.Rabiner,B.Gold,Prentice Hall,1975

Please send any problems,suggestions, or ideas to the
address listed or leave a message on our RBBS. If your having any
problems and would like to contact us, feel free to call from 9am
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4/26/85