Splitting the Unit Delay -
Tools for Fractional Delay Filter Design

These pages give instructions for downloading and using the MATLAB Files associated with the article:

Timo I. Laakso, Vesa Välimäki, Matti Karjalainen, and Unto K. Laine,
"Splitting the unit delay - tools for fractional delay filter design,"
IEEE Signal Processing Magazine, vol. 13, no. 1, January 1996.

How to download the Matlab files
Description of the files

How to download

The file fdtools.zip has been compressed using pkzip. The Matlab files have been tested to run correctly on Unix, Macintosh, and Windows 3.xx platforms.

Description of the files

The accompanying set of MATLAB routines can be used to design fractional delay FIR and allpass filters and to plot their responses. The basic MATLAB and the MATLAB Signal Processing Toolbox are needed.

The Figures included in the above article can be plotted using the files FDFIR2.M and FDAP2.M. The former generates the magnitude and phase delay curves and the impulse responses for FIR fractional delay (FD) filters. The latter gives the phase delay responses and the impulse responses of the allpass fractional delay filters. These two functions use the other files which are the actual filter design functions and their subroutines.

The FIR FD package consists of the following 11 MATLAB routines (m-files):

The allpass FD package consists of the following MATLAB routines (m-files):

Comments or suggestions can be sent by e-mail to
Timo I. Laakso or to Vesa Välimäki.


This software is being provided to you, the LICENSEE, by Helsinki University of Technology (HUT) under the following license. By obtaining, using and/or copying this software, you agree that you have read, understood, and will comply with these terms and conditions: Permission to use, copy, modify and distribute, including the right to grant others rights to distribute at any tier, this software and its documentation for any purpose and without fee or royalty is hereby granted, provided that you agree to comply with the following copyright notice and statements, including the disclaimer, and that the same appear on ALL copies of the software and documentation, including modifications that you make for internal use or for distribution:

Copyright 1996 by Helsinki University of Technology (HUT) All rights reserved. The allpass design package is copyrighted by NOKIA, MIT, and GE (1994).

THIS SOFTWARE IS PROVIDED "AS IS", AND Helsinki University of Technology MAKE NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED. By way of example, but not limitation, Helsinki University of Technology MAKE NO REPRESENTATIONS OR WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF THE LICENSED SOFTWARE OR DOCUMENTATION WILL NOT INFRINGE ANY THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS. The name of the HUT may NOT be used in advertising or publicity pertaining to distribution of the software. Title to copyright in this software and any associated documentation shall at all times remain with the HUT and USER agrees to preserve same.

Enjoy your designs!

Timo Laakso and Vesa Välimäki
London, January 26, 1996

Last update: Feb. 1, 1996
Helsinki University of Technology
Laboratory of Acoustics and Audio Signal Processing