4results about How to "Increase sensing distance" patented technology

The application discloses a compensation device and method for laser phase noise of an optical frequency domain reflectometer, and relates to the technical field of distributed optical fiber sensing. The compensation device comprises a sweep laser source module, a main interferometer module, an auxiliary interferometer module and a signal processing module. The sweep laser source module is used for outputting a first sweep laser beam and a second sweep laser beam. The main interferometer module receives the first sweep laser beam and generates a first beat frequency signal related to the position of a scattering point of a sensing optical fiber. The auxiliary interferometer module receives the second sweep laser beam and generates a second beat frequency signal related to the position of a weak reflection point of an auxiliary optical fiber. The signal processing module collects the first beat frequency signal and the second beat frequency signal, extracts phase terms of the sensing optical fiber and the auxiliary optical fiber respectively, and realizes phase noise compensation. The compensation method realizes the function of the compensation device, that is, realizes phase noise compensation, analyzes the spectrum of compensation information again, and demodulates strain information along the sensing optical fiber. The application realizes uniform compensation of phase noise, and improves the system measurement distance, spatial resolution and strain accuracy.

This invention relates to an optical frequency domain reflection system and method based on a voltage-controlled oscillator (VCO). The system mainly includes an arbitrary function generator, a laser, a VCO, a single-sideband modulator, an auxiliary interferometer, a main interferometer, and a polarization beam splitter. The arbitrary function generator, laser, VCO, and VSB modulator work together to generate the sweeping light required for measurement. This sweeping light is split into two paths: one path enters the main interferometer as probe light, and the other path enters the auxiliary interferometer to obtain the instantaneous frequency of the probe light. Based on the instantaneous frequency, the signal from the main interferometer is resampled using a one-dimensional interpolation method. This invention uses a low-cost, small-sized VCO as the radio frequency signal generator to generate a sweeping signal with fast frequency modulation performance, and compensates for phase noise caused by the nonlinearity of the sweeping signal by designing the optical path of the auxiliary interferometer and using a linear interpolation algorithm.

This invention discloses a hybrid direct and coherent seismic exploration system and method. It employs multi-frequency time-delay dual-pulse direct detection to acquire the detection signal, and then uses moving average differential detection to determine the vibration location. Heterodyne coherent detection acquires multi-frequency optical pulse electrical signals, which are then bandpass filtered. The resulting signals of multiple different frequencies are then subjected to I / Q quadrature demodulation. Phase reconstruction is performed based on the phase curves at the determined vibration location to obtain the final vibration phase curve. By using a direct detection structure to initially determine the vibration location, and a coherent detection structure to directly reconstruct the vibration curve based on the obtained location, the detection efficiency is improved. This also enhances the signal-to-noise ratio and sensing distance of the distributed fiber optic vibration sensing system.

The utility model discloses a ship lock miter gate waterproof absolute opening on -line monitoring device, the utility model relates to gate absolute opening monitoring technical field. The ship lock miter gate waterproof absolute opening on -line monitoring device, including moving ruler, static magnetic pointer and miter gate, moving ruler includes arc slot, magnetism plate and PCB array, and PCB array sets up in the inside of arc slot, and magnetism plate sets up in the lower surface of arc slot, and PCB array includes PCB board, and the outer surface of PCB board is provided with hall device array and controller, and static magnetic pointer includes support, angle code and permanent magnet, and angle code is symmetrically arranged in the both sides of permanent magnet, the utility model discloses non -contact means, installs the sensor on the gate, and the absolute opening information of gate is obtained through the method of direct monitoring.