Joint wavelet denoising for distributed temperature sensing
Aspects of the present disclosure describe systems, methods, and structures for distributed temperature sensing that employ joint wavelet denoising to achieve desirable signal-to-noise ratio(s) over extended sensor fiber distances.
1. A distributed temperature sensing (DTS) system comprising:
a length of optical sensing fiber;
an optical interrogator unit that generates optical pulses, introduces them into the optical fiber, and receives backscattered Stokes (S) and anti-Stokes (AS) signals from the optical fiber; and
a computer programmed to perform
joint wavelet denoising (WD) of both AS and S signals at the same time; and
determine the one or more temperatures from the denoised AS and S signals; and
output the determined one or more temperatures;
wherein the WD of both AS and S signals is achieved by a method selected from the group consisting of VisuShrink, SureShrink, and MinimaxShrink, the selected method having a Daubechies 4 wavelet (db4) as a base wavelet and a decomposition level of 6.
2. The system of claim 1
wherein the AS and S signals are decomposed into multiple layers of wavelet coefficients.
3. The system of claim 2 wherein the computer is programmed to
determine a correlation between the AS and S wavelet coefficients at each one of the multiple layers.
4. The system of claim 3 wherein the computer is programmed to
determine a jointly estimated noise threshold and identifying noise components by comparing correlations with the jointly estimated noise threshold.
5. The system of claim 4 wherein the computer is programmed to
apply a thresholding or shrinkage function on both the AS and S wavelet coefficients simultaneously, according to the identified noise components.
6. The system of claim 5 wherein the computer is programmed to
reconstruct denoised S and AS signals by inverse wavelet transform.