Signal Comparing Normalized Generalized Levenshtein Distance-Based Searching Method for Modulation Period of Micro-Doppler Signal

A searching method using the signal comparing normalized generalized Levenshtein distance (SC-NGLD) as the cost function is proposed to search for the modulation period of micro-Doppler (m-D) signal. NGLD is an improved form of edit distance (also known as “Levenstein distance”) and is a commonly used distance to deal with misspelled character strings. In this paper, the string-matching-used NGLD is upgraded to SC-NGLD and is given the power of computing the differences between two numerical-signal strings. When our only propose is to obtain the modulation period of m-D signal and indicate some feature such as the heart rate and respiratory rate of a human or the rotation rate of helicopter blades, using the SC-NGLD as the cost function to search for the modulation period of m-D signal in time domain avoids the time-frequency analysis step, thus the computing burden caused by time-frequency analysis is eliminated. Besides, the proposed method has strong robustness in low pulse repetition frequency or low signal-to-noise ratio conditions. The feasibility of the proposed method is validated by processing both the simulated m-D signal and the experimental scattered signal from helicopter blade models.