Underwater Missile-borne Imitation Bat Detector The CF / FM Transmitter Signal Control Method

Underwater ultrasonic detector on-board was designed for the modern fuze of airborne, and ship-borne rocket depth charges used in shallow sidewall anti-submarine warfare. It mimicked the bat's vocalization and hearing function, can capture,track and locate the target. The signal generation and controlling determined the working model of target detector, was one of the core of signal processing center system. This thesis designed a kind of signal controlling device for signal generator in signal processing central system, solving the problem of signal auto conversion.Based on the analysis of bats detection, determined to use CW,LFM signals. The signal control plan of imitation bats ultrasonic detector were put forward, designed two control signals of power on-board and echo signal, controlling in logical sequence. The signal generator was startup under control of power on-board, launched CW signal, the system was in target search stage, if echo signal was confirmed in an exploration cycle, then switched to launch LFM signal, the system was in the target tracking and attacking stage, otherwise continued to launch CW signal. The echo signal was confirmed after two levels of discrimination. The first level was "simple discrimination", to check the output existing doppler shift signal, If existing, indicated that there was an object in the direction of detection, completing the "discovery" function; The second level was "meticulous discrimination", if simple discrimination indicated the existing of doppler shift signal, then confirmed whether it was from detecting target by two-door control signal, completing the "recognition" function.In order to validate the feasibility and validity of signal control plan, used DDWS method, produced CW and LFM signals in the FPGA device, and designed two-door control signal to confirmed doppler shift signal,and then simulated in Quartus II.The echo signal processing circuits was designed, including the impedance matching and former amplifier,AGC,frequency mixing and filter circuits, used to collect doppler shift signal, to realize "simple discrimination". In order to validate the main function of echo signal processing circuits, the experiments of AGC and filter were designed.Experimental results showed that the two modules worked normally, can complete the design requirements.