Design And Implementation Of Resonant Fog Digital Processing Platform Based On Beat Frequency Detection

On the basis of Sagnac effect,resonant fiber optic gyro(R-FOG)USES the principle of light wave superposition to generate resonance phenomenon through the fiber resonator cavity.It can measure the angular velocity with only a few meters of fiber,which has many advantages in miniaturization and low cost.Traditional R-FOG design scheme using the laser large volume,high cost,in order to solve this problem,this paper designed a kind of to DFB laser drive system and the beat frequency signal detection system as the core of the resonant optical fiber gyro digital processing platform,can effectively reduce the laser volume and cost and omit the modem and digital frequency locking related links,and the measuring range is no longer restricted by demodulation linear area.This thesis mainly completes the following work:First of all,introduced the Sagnac effect and the basic principle of optical based on beat frequency R-FOG related technical principles,given the role of transmission type optical fiber resonator principle and mathematical model,and on this basis further describes the beat frequency in the FOG of mathematical model,the introduction of laser from the injection locking technique to realize frequency locking,finally determine the gyro based on beat frequency detection optical path system as a whole.Secondly,a digital processing platform design scheme based on the generation and detection technology of beat frequency signal is designed for the related requirements of gyro output beat frequency signal and its detection.The scheme mainly includes a DFB semiconductor laser drive system based on constant temperature and constant current control and a beat frequency signal detection system based on TDC measurement technology.This paper introduces in detail the circuit design of constant temperature and constant current closedloop control loop,and briefly introduces the TDC time measurement technology principle and general detection method.Compared with the traditional R-FOG digital platform,the digital processing platform designed in this paper is more concise in structure,smaller in volume and lower in cost,and it reduces the influence of tonality interval on measurement and expands the measurement range.Then,the hardware circuit of digital processing platform is realized.Contains: the STM32 as the core control unit,designed based on LTC1923,AD,DA,and high precision op-amp components such as closed loop control of laser constant temperature,constant current control system,the system makes the laser working in steady state,output of narrow line width,and higher purity of the laser signal,and free tuning drive current size,thereby mobile laser center frequency;Taking FPGA as the core operation unit,a beat frequency signal detection system based on TDC-GP22 is designed.Finally,build the test environment of the digital platform,and test each module and the whole platform.The constant temperature stability of the laser driving system is tested.The test results show that the temperature stability is good.The stability of constant current and linearity of tuning operation are tested.The results show that the stability of current and linearity of tuning are good.The experiment results show that the laser drive system works stably and can produce an obviously stable beat frequency.The measuring work of time length of beat frequency detection system has been completed.The result of time measurement shows that the designed beat frequency detection system works normally and can realize the measurement of time interval information,which verifies the rationality of the beat frequency detection system.