SNR Enhancement for Comparator-Based Ultra-Low-Sampling Φ-OTDR System Using Compressed Sensing

Area of Science:

• Optoelectronics
• Signal Processing
• Sensor Technology

Background:

• Coherent phase-sensitive optical time-domain reflectometry (Φ-OTDR) systems generate large data volumes, posing transmission, processing, and storage challenges.
• Existing hardware methods for data reduction, like comparator-based undersampling, increase quantization noise and degrade signal-to-noise ratio (SNR).

Purpose of the Study:

• To develop a method for reducing data volume in Φ-OTDR systems while maintaining or enhancing detection performance.
• To address the SNR deterioration caused by hardware-based data reduction techniques.

Main Methods:

• Implemented a hardware approach using a comparator combined with undersampling to simultaneously reduce sampling rate and resolution.
• Applied compressed sensing techniques to denoise demodulated phase signals, exploiting the spectral sparsity of vibrations.
• Utilized a 1-bit comparator with a 62.5 MS/s sampling rate to capture an 80 MHz beat signal, reducing data to 7.45 MB/s.

Main Results:

• Achieved a significant reduction in sampled data volume.
• Demonstrated substantial SNR enhancement for reconstructed sinusoidal signals (23.7 dB to 28.7 dB) using compressed sensing.
• Successfully reconstructed multi-frequency vibrations with high SNR, validating the technique's effectiveness.

Conclusions:

• The proposed technique effectively reduces the hardware burden of Φ-OTDR systems.
• Compressed sensing successfully compensates for SNR loss and enhances detection performance.
• This approach offers a viable solution for high-performance, low-data-volume Φ-OTDR applications.