A Random Modulation and Demodulation Method for Suppressing Cross-Coupling of Fiber Optic Gyroscope

Abstract

The invention discloses a random modulation and demodulation method for suppressing cross-coupling of an optical fiber gyroscope. Firstly, a random or pseudo-random sequence is used to generate two groups of mirror modulation sequences that are opposite to each other, and the two modulation sequences that are mirror images of each other are crossed in pairs. Combine to form the final modulation sequence; then modulate the optical phase of the gyroscope; finally, the digital central processor demodulates the voltage value received by the photodetector according to the corresponding demodulation sequence to obtain the rotational speed error of the gyroscope, and convert the error The signal is used as the feedback signal of the closed-loop loop to realize the closed-loop control of the gyroscope. The method realizes the statistical decorrelation of modulation and demodulation by using random numbers to generate modulation sequences, and suppresses the cross-coupling between the modulation signal and the demodulation signal in the fiber optic gyroscope. At the same time, the method can realize demodulation in any integer multiple of the fiber ring transit time, which speeds up the response of the gyroscope closed loop and improves the dynamic performance of the system.

Description

technical field [0001] The invention relates to a modulation and demodulation method of an interference-type digital closed-loop fiber optic gyroscope, in particular to a random modulation and demodulation method for suppressing cross-coupling of the fiber optic gyroscope. [0002] technical background [0003] Digital closed-loop fiber optic gyroscope is an instrument for measuring angular velocity. It is widely used in inertial systems such as navigation and positioning. It mainly includes light source, coupler, Y waveguide, fiber optic ring, photodetector, and digital processing circuit. [0004] The basic principle is that the light emitted by the light source is divided into two beams of forward and reverse propagation light waves through the Y waveguide, and the digital processing circuit applies a modulation signal at the Y waveguide to perform phase modulation on the light waves. Converted into an electrical signal, the central processor samples and demodulates the el...

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Problems solved by technology

At the same time, it is pointed out in the article that in a demodulation cycle, the number of positive and negative signs of the demodulated signal must be equal, but due to the randomness of the modulation sequence, the demodulation cycle of the gyro will be very long (about one second) and not fixed, which means It will lead to longer closed-loop response of gyroscope and lower dynamic performance

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