Random modulation and demodulation method for restraining cross coupling of optical fiber gyroscope

Abstract

The invention discloses a random modulation and demodulation method for restraining cross coupling of an optical fiber gyroscope. A random or pseudo-random sequence is used for generating two sets ofopposite mirror image modulation sequences, and the two modulation sequences which are mirror images are combined to form a final modulation sequence; the optical phase of the gyroscope is modulated;and finally, a digital center processor performs demodulation processing on the voltage value received by a photoelectric detector according to the corresponding demodulation sequence, the rotating speed error of the gyroscope is obtained, and the error signal serves as a feedback signal of a closed loop, so that closed-loop control of the gyroscope is realized. According to the method, the modulation sequence is generated by adopting a random number, the correlation of modulation and demodulation on statistics is realized, and the cross coupling between modulation signals and demodulation signals in the optical fiber gyroscope is inhibited. Meanwhile, the method can achieve demodulation within any integer multiple optical fiber ring transit time, the response of the gyroscope closed-loopis accelerated, and the dynamic performance of a system is improved.

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. technical background [0002] 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. [0003] 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 electrical...

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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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