Research on the Performance Optimization of the Fiber-optic Hydrophone
|School||Harbin Engineering University|
|Course||Signal and Information Processing|
|Keywords||PGC detection Phase frequency characteristics Low-pass filter Dynamic Range Cutoff frequency|
Fiber optic hydrophone since its inception, the value of the huge military and civilian value has been driven by the rapid development , has gradually shifted from the laboratory stage to engineering applications . This thesis work is dedicated fiber optic hydrophone practical design and research . This paper first describes the fiber optic interferometer modulation and detection theory , introduces two practical detection demodulation scheme, namely the phase generated carrier (PGC) technology , 3 × 3 coupler multiphase detection technology. Then the fiber optic hydrophone system are two important technical indicators sensitivity and dynamic range for a detailed analysis and discussion of the fiber-optic hydrophone system phase sensitivity and sound pressure sensitivity , and two physical significance and sensitivity of the intrinsic link ; introduction upper limit of the dynamic range , dynamic range limit ( the noise floor ) concept and analyze the dynamic range of factors. In order to improve the fiber-optic hydrophone system's overall performance , the text of the PGC demodulation fiber optic hydrophone system lowpass filter frequency characteristics were studied in depth , in order to transmit without distortion based on the theory analysis of the low-pass filter frequency characteristic and phase -frequency characteristics , and draw conclusions. To ensure that no distortion of the demodulated signal output , requires a low-pass filter has a sharp cutoff and linear phase characteristics ; the low-pass filter with frequency characteristic is nonlinear , PGC demodulation system will cause the frequency component of the output signal changes to fiber optic hydrophone system output signal spectrum analysis cause interference . The paper also combines PGC demodulation system simulation, the cutoff frequency of the low pass filter to optimize the settings to improve the system dynamic range limit. These conclusions for future fiber optic hydrophone testing and research provides an important reference .