Device and method for improving sampling rate in frequency domain of OFDR

Abstract

The invention relates to a device and method for increasing the OFDR frequency domain sampling rate. The device includes a frequency-sweeping laser, a fiber coupler, a measurement module, an auxiliary module, a data acquisition card, and a computer. In the measurement module, the beat frequency interference occurs between the reference arm signal and the measurement arm, and the generated beat frequency signal is collected by the external clock signal generated in the auxiliary module to control the frequency domain acquisition such as the data acquisition card. According to the size of the measurement length, the sampling is divided into N times. Under the condition that the frequency difference between the two arms of the auxiliary module interferometer is fixed, the frequency shifter is used to adjust the frequency shift of the sampling signal for data acquisition. The FFT operation is performed after the multiple acquisition data are superimposed to obtain the final result. This method improves the OFDR frequency domain sampling rate, which is beneficial to expand the OFDR measurement range, and the measurement range can be adjusted according to user needs. The method is convenient, the result is accurate, and it can meet the needs of various measurement environments.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, and more specifically, to a device and a frequency domain sampling method for increasing OFDR frequency domain sampling rate. Background technique [0002] As the most promising technology in the field of distributed optical fiber sensing, the research and application of optical frequency domain reflectometry technology has always been a hot issue of widespread concern. Based on the combination of frequency domain analysis and optical heterodyne technology, compared with traditional OTDR technology, OFDR technology has higher resolution and larger dynamic range, and is widely used in optical communication measurement, strain and temperature sensing in engineering and medical fields with broadly application foreground. [0003] The OFDR system uses a swept source. Affected by factors such as temperature changes and device vibrations, the output laser spectral lines will change, and...

AI Technical Summary

Problems solved by technology

If you want to expand or reduce the measurement range, you must remake and replace the auxiliary interferometer, otherwise there will be problems such as over-range measurement or measuring short-distance optical fibers with a large-range system, resulting in long measurement time and slow speed.

Moreover, since the spatial resolution of OFDR is usually at the micron level, a single acquisition of data points can reach tens of millions during long-distance measurement, and the sampling frequency interval is small. It is difficult for conventional data acquisition cards and computers to meet the requirements of data acquisition and calculation processing. Use high-performance modules, which will increase the cost of the OFDR system

Images