Feature Extraction of Radar Emitter Harmonic Power Constraint Based on Nonlinear Characters of the Amplifier

In radar countermeasures systems, because each emitter has its own electromagnetic properties inside its transmitted signal, the specific emitter can be identified using received radar signals. Traditionally, the specific emitter identification (SEI) depends on analyzing the time-frequency structure within the usage band. In this paper, a new SEI feature extraction approach based on autocorrelation analysis is proposed. To characterize the nonlinearity of the amplifier in the transmitter, the harmonic power constraint characteristic of the output signal of the amplifier is analyzed, and a power series model is applied to describe the output signal. For different amplifiers, harmonic power constraint properties are different. We present the autocorrelation analysis method to estimate each harmonic power spectrum and extract harmonic power ratio signature features from output signal of the amplifier. The validity of the proposed method is confirmed by simulation experiments.