UWEE Tech Report Series

Improved Modulation Spectrum Through Multi-scale Modulation Frequency Decomposition


UWEETR-2004-0024

Author(s):
Somsak Sukittanon, Les E. Atlas, James W. Pitton, and Karim Filali

Keywords:
modulation spectrum, feature extraction, pattern recognition, signal interception, digital modulation signals, short-term features, long-term features, multiscale, wavelet

Abstract

The modulation spectrum is a promising method to incorporate dynamic information in pattern classification. It contains important cues about the nonstationary content of a signal and yields complementary improvements when it is combined with conventional features derived from short-term analysis. Many prior modulation spectrum approaches are based on uniform modulation frequency decomposition. The drawbacks of these approaches are high dimensionality and a lack of a connection to human perception of modulation. This paper presents multi-scale modulation frequency decomposition and shows an improvement over standard modulation spectrum in a digital communication signal classification task. Features derived from this representation provide lower classification error rates than those from a constant-bandwidth modulation spectrum whether used alone or in combination with short-term features.

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