CN-121977624-A - BOTDR system-based rapid demodulation device and method

CN121977624ACN 121977624 ACN121977624 ACN 121977624ACN-121977624-A

Abstract

The invention discloses a BOTDR system-based rapid demodulation device, which comprises a photoelectric detector, a low-noise amplifier, a splitter, a first mixer, a second mixer, a first filter, a second filter, a first data acquisition system, a second data acquisition system, a phase shift module, a local oscillator and a signal processing module. According to the invention, by arranging the mixer, the filter and the data acquisition module, the traditional local oscillator scanning method is avoided from measuring at N different frequency points to acquire the frequency profile, and the demodulation speed is improved.

Inventors

LI JIANWEI
ZHANG CHENGXIAN
ZHAO HAO

Assignees

波科激光(嘉善)有限公司
上海松江波汇光电研究院

Dates

Publication Date: 20260505
Application Date: 20260407

Claims (7)

1. A BOTDR system-based rapid demodulation device is characterized by comprising a photoelectric detector, a low-noise amplifier, a splitter, a first mixer, a second mixer, a first filter, a second filter, a first data acquisition system, a second data acquisition system, a phase shifting module, a local oscillator and a signal processing module, wherein the photoelectric detector is connected with the low-noise amplifier, the low-noise amplifier is connected with the splitter, the splitter is respectively connected with the first mixer and the second mixer, the first mixer is connected with the first filter, the first filter is connected with the first data acquisition system, the first data acquisition system is connected with the signal processing module, the second mixer is connected with the second filter, the second data acquisition system is connected with the signal processing module, the local oscillator is respectively connected with the first mixer and the phase shifting module, and the phase shifting module is connected with the second mixer.
2. The rapid demodulating device based on the BOTDR system according to claim 1, wherein the photoelectric detector receives an optical signal and converts the optical signal into an electrical signal, the photoelectric detector outputs the electrical signal to the low noise amplifier for signal amplification, the electrical signal is split into a first electrical signal and a second electrical signal through the splitter, the local oscillator mixes the generated local oscillator signal with the first electrical signal in the first mixer, the first electrical signal is filtered through the first filter after being mixed, and the first data acquisition system digitally acquires the filtered electrical signal and inputs the digital signal to the signal processing module.
3. The rapid demodulating device based on the BOTDR system according to claim 2, wherein the local oscillator mixes the generated local oscillator signal with a second path of electric signal in a second mixer after phase shifting by a phase shifting module, the second path of electric signal is filtered by a second filter after being mixed, the second data acquisition system digitally acquires the filtered electric signal and inputs the filtered electric signal to the signal processing module, and the signal processing module processes the received first path of electric signal and the received second path of electric signal to calculate the phase and frequency of the signal.
4. A BOTDR system-based rapid demodulation method is characterized by comprising the following steps that an optical detector receives an optical signal and converts the optical signal into an electric signal, the optical detector outputs the electric signal to a low-noise amplifier for signal amplification, the electric signal is divided into a first electric signal and a second electric signal through a branching device, a local oscillator mixes the generated local oscillator signal with the first electric signal in a first mixer, the first electric signal is filtered through a first filter after being mixed, a first data acquisition system digitally acquires the filtered electric signal and inputs the digital signal to a signal processing module, the local oscillator mixes the generated local oscillator signal with the second electric signal in a second mixer after being subjected to phase shift through a phase shift module, the second electric signal is filtered through a second filter after being mixed, the second data acquisition system digitally acquires the filtered electric signal and inputs the received first electric signal and the second electric signal to a signal processing module, and the phase and the frequency of the signal are calculated.
5. The method of claim 4, wherein the first and second filters are planar microstrip filters and the filters are etched on the PCB in the form of waveguides when the local oscillator frequency is 9GHz and the stokes signal frequency after down-conversion is in the range of 2 GHz.
6. The method of claim 4, wherein the local oscillator frequency is set to 10.5GHz, the stokes signal frequency after down-conversion falls to a range of 500MHz, and the first filter and the second filter are high-order butterworth filters.
7. The method of claim 4, wherein the local oscillator signal mixed with the second electrical signal is phase shifted by 90 °.

Description

BOTDR system-based rapid demodulation device and method Technical Field The invention belongs to the technical field of optical fiber sensing, and particularly relates to a BOTDR system-based rapid demodulation device and method. Background The rapid demodulation technology based on the Brillouin Optical Time Domain Reflectometry (BOTDR) system is a key technical breakthrough developed under the background that the requirements of distributed strain and temperature real-time perception are increasingly urgent in the fields of modern large infrastructure structure health monitoring, oil gas pipeline safety precaution, geological disaster prevention and control and the like, the traditional BOTDR technology is based on the self-Brillouin scattering effect, and can realize spatially continuous strain and temperature distribution measurement by carrying out point-by-point measurement on Brillouin Frequency Shift (BFS) propagated in an optical fiber, and has the unique advantages of electromagnetic interference resistance, intrinsic safety, long monitoring distance and the like. However, the demodulation process usually depends on complex frequency scanning and multipoint averaging, so that a single measurement takes up to several minutes or even tens of minutes, and it is difficult to meet the application requirements of dynamic change or real-time early warning. Disclosure of Invention The invention aims to overcome the defects in the prior art, and the rapid demodulation device and method based on the BOTDR system, which avoid the need of measuring at N different frequency points to obtain a frequency profile by the traditional local oscillator scanning method and improve the demodulation speed by arranging a mixer, a filter and a data acquisition module. In order to achieve the above object, the present invention provides the following technical solutions: The device comprises a photoelectric detector, a low noise amplifier, a branching device, a first frequency mixer, a second frequency mixer, a first filter, a second filter, a first data acquisition system, a second data acquisition system, a phase offset module, a local oscillator and a signal processing module, wherein the photoelectric detector is connected with the low noise amplifier, the low noise amplifier is connected with the branching device, the branching device is respectively connected with the first frequency mixer and the second frequency mixer, the first frequency mixer is connected with the first filter, the first data acquisition system is connected with the signal processing module, the second frequency mixer is connected with the second filter, the second filter is connected with the second data acquisition system, the second data acquisition system is connected with the signal processing module, the local oscillator is respectively connected with the first frequency mixer and the phase offset module, and the phase offset module is connected with the second frequency mixer. Further, the photoelectric detector receives the optical signal and converts the optical signal into an electric signal, the photoelectric detector outputs the electric signal to the low-noise amplifier for signal amplification, the electric signal is divided into a first electric signal and a second electric signal through the branching unit, the local oscillator mixes the generated local oscillator signal with the first electric signal in the first mixer, the first electric signal is filtered through the first filter after being mixed, and the first data acquisition system digitally acquires the filtered electric signal and inputs the filtered electric signal to the signal processing module. Further, the local oscillator carries out phase deviation on the generated local oscillator signal through a phase deviation module, then carries out frequency mixing with a second path of electric signals in a second frequency mixer, the second path of electric signals are filtered through a second filter after being mixed, a second data acquisition system carries out digital acquisition on the filtered electric signals and then inputs the digital acquisition to a signal processing module, and the signal processing module processes the received first path of electric signals and the received second path of electric signals to calculate the phase and the frequency of the signals. A BOTDR system-based rapid demodulation method comprises the following steps that an optical signal is received by a photoelectric detector and then converted into an electric signal, the electric signal is output to a low-noise amplifier to be amplified by the photoelectric detector, the electric signal is divided into a first electric signal and a second electric signal by a branching device, the generated local oscillator signal and the first electric signal are mixed in a first mixer, the first electric signal is filtered by a first filter after being mixed, the filtered electric signal is input to