Doppler Signal’s Frequence Detection Base On Duffing Oscillator

It is very important to improve the ability of extracting radio fuze’s Doppler signal. In order to solve the problem of extracting the radio fuze’s Doppler signal in the complex electromagnetic environment, chaos theory is introduced into the detection on radio fuze’s target echo signal, in hope of enhancing the Doppler signal detection ability dramatically in ultra-low signal-to-noise ratio(SNR).The project carries out new method research and verification work about radio fuze’s Doppler signal detection based on chaotic oscillator.Based on the analysis of Duffing oscillator very sensitive to the initial period signal, a frequency-detected system of the fuze Doppler signal based on Duffing Oscillator is established. Firstly Duffing oscillator dynamics and the influence of system parameters on Fuze Doppler signal detection effectiveness having been analyzed, the parameters are optimized to extend the applicability of Duffing oscillator system on fuze Doppler signal detection; Secondly due to the detailed analysis from the applicaion on Duffing oscillator intermittent chaotic motion mechanism and the time-domain waveform characteristics of the system output, a simple and effective detection of zero-crossing interval as the criteria for chaos is proposed, and the use of the frequency scanning on oscillator intermittent chaotic motion for the testing of Fuze Doppler signal frequency is determined; then Matlab software is utilized to have the simulation of the method on Fuze Doppler signal chaos detection and the quantitative analysis for detecting errors, which will obtain the best signal to noise ratio of the system. Finally a signal frequency detection system based on DSP with the main core TMS320C6713 is built, and the data obtained from CCS is compared with the data from the simulation to verify the method’s validity, practicality and the system’s effectiveness.Experimental results show that Duffing oscillator system possesses good noise immunity, while the detection effect is affected by the sampling step. When the system sampling rate has reached 2,000 times as the measured Doppler signal frequency, detected signal to noise ratio is about-30 dB with the measurement accuracy up to 99%.