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MLS

Maximum-Length Sequences (MLS) are pseudorandom signals which can be used to excite a system, the output of which can be quickly inverted to determine the system's impulse response. They are spectrally white and have a unit-impulse autocorrelation function. This method of testing is preferable to impulse testing as signal energy is spread out over time, providing greater SNR and reducing nonlinear effects. This package includes a short tutorial, some MATLAB examples and the source code.

Files

runme.m

In-context usage, demonstrating an MLS sequence convolved with a room impulse response, then deconvolved to recover the impulse response.

GenerateMLSSequence.m

Generates an MLS sequence of predetermined order and repetition.

AnalyseMLSSequence.m

Analyses an MLS sequence that has been convolved with the system under test.

Download

MLS Theory

MATLAB Toolkit

References

  1. J. Borish and J. B. Angell, "An Efficient Algorithm for Measuring the Impulse Response Using Pseudorandom Noise," J. Audio Eng. Soc., vol. 31, pp. 478—489, 1983.
  2. D. D. Rife and J. Vanderkooy, "Transfer-Function Measurement with Maximum-Length Sequences," J. Audio Eng. Soc., vol. 37, pp. 419—444, 1989.
  3. M. Cohn and A. Lempel, "On Fast M-Sequence Transforms," IEEE Trans. Inf. Theory, IT-23, pp. 135—137, 1977.

Copyright

Copyright © 2005-2009 M. R. P. Thomas.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA