# Error Analysis and Suppression of Rectangular-Pulse Binary Phase Modulation Technology in an Interferometric Fiber-Optic Sensor

## TL;DR

This paper analyzes and improves the performance of a phase modulation method used in fiber-optic sensors to enhance signal quality and accuracy.

## Contribution

The paper introduces an improved error suppression method using ellipse fitting of Lissajous figures, significantly boosting signal quality.

## Key findings

- The RPBPM method shows advantages in efficiency and complexity over traditional methods.
- An improved ellipse fitting method increases the SINAD from 26.3 dB to 37.1 dB.
- Experimental results confirm excellent performance in practical vibration systems.

## Abstract

In the field of interferometric fiber-optic sensing, the phase-shifting technique is well known as a highly efficient method for retrieving the phase signal from the interference light intensity. The rectangular-pulse binary phase modulation (RPBPM) method is a typical phase-shifting method with the advantages of high efficiency, low complexity, and easy array multiplexing. Exploring the impact of the parameters on the performance is of great significance for guiding its application in practical systems. In this study, the influence of the sampling interval and modulation depth deviation involved in the method is analyzed in detail. Through a comparative simulation analysis with the traditional heterodyne and phase-generated carrier methods, the superiority of the RPBPM method is effectively validated. Meanwhile, an improved method based on the ellipse fitting of the Lissajous figure is proposed to compensate for the error and improve the signal-to-noise-and-distortion ratio (SINAD) from 26.3 dB to 37.1 dB in a specific experiment. Finally, the experimental results guided by the above method show excellent performance in a practical vibration system.