Symbolic time series analysis for measuring complexity in radar emitter signals

STSA(symbolic time series analysis) is a effective tool used in many fields to measure randomness and deterministic of nonlinear system. In order to investigate the complex characteristics of radar intrapulse modulation signals in modern electronic warfare, the entropy statistics of STSA is defined in this paper. The symbolic entropy algorithm of STSA based on information theory, chaos time series analysis and symbolic dynamics is developed for quantitatively extracting intrinsic information of radar emitter signals. Simulated signals derived from seven typical radar modulation signals and their overlapping signals are examined and compared when SNR varies in the range from 0dB to 30dB. The simulation results demonstrate that the introduced STSA method has better characteristics of separating the same signals with different modulation parameter and the outlier signals overlapped by different modulation signals. Moreover, the algorithm can be easily implemented and computationally efficient.