Table 5.

Comparison and analysis of SNR improvement methods based on Raman distributed optical fiber sensing

Scheme Types	Advantages	Characteristic	Representative Results
Pulse Coding	It can effectively improve the SNR and sensing distance at the same time.	An extra expense and complex for practical application.	3.9 °C @ 39.0 km92, Figures of merit: 10; °C @ 1.0 km91, Figures of merit: 10;
Algorithm Denoising	Operation process is simple. Reduce the number of averaging and optimize the measurement time of the system.	Some useful signals may be filtered out.	2.7 °C @ 30.0 km98, Figures of merit: 11.11
Rayleigh Optical Noise Suppression	Operation process is simple.	It cannot eliminate electrical noise, and needs to be used in combination with other denoising methods.	1.7 °C @ 9.1 km109, Figures of merit: 5.35,
Noise Suppression in the Demodulation Stage	The calibration process is omitted, and operation is simple.	It needs to be used in combination with other denoising methods.	0.18 °C @ 17.0 km111, Figures of merit: 94.4