| 摘要 |
<p>A BOTDA system based on pulse coding and coherent detection, comprising a narrow linewidth laser (10), two polarization-maintaining couplers (11, 12), a microwave signal source (17), two electrooptical modulators (13, 15), a test optical fibre (18), an optical circulator (19), a 3 dB coupler (20), a scrambler (16), a pulse signal source (14), a balancing photoelectric detector (21), a spectrum analyzer (22), a digital signal processing unit (23), and a frequency shifter (9). The system adopts the pulse coding technology and the coherent detection method at the same time, and can improve the signal-to-noise ratio and measurement precision of BOTDA and increase the sensing distance; and the system has a breakpoint monitoring function, can effectively overcome the defect that the conventional BOTDA requires double-end access, resulting in the occurrence of breakpoints and work failure, and enhances the adaptability and practicality of a sensing system.</p> |
