DAS Over 1,007-km Hybrid Link With 10-Tb/s DP-16QAM Co-Propagation Using Frequency-Diverse Chirped Pulses

High resolution seafloor thermometry for internal wave and upwelling monitoring using Distributed Acoustic Sensing

“…This also implies that, at long distances, DTS measurements need to be averaged over longer times (tens of minutes or more) and over larger gauge lengths to achieve acceptable performances 110 . In contrast, the Rayleigh scattered power is 20 to 30 dB higher than the Brillouin and Raman scatterings typically used for temperature sensing, respectively 111 , so that longer sensing ranges are attainable with DAS (up to 100 km and more 112 ). At the same time, diverse techniques exist to preserve optimal DAS repeatability at long distances 21 .…”

“…When implemented, the SMART cable initiative 115 should provide calibrated temperature sensors at the optical repeaters of new cables. It is also worth reminding the significant efforts and recent progress on the improvement of the sensing range, SNR characteristics and the simultaneous use of DAS instruments on operating telecommunication fibers 21 , 112 , 116 – 120 . Although standard DAS units are expected to suffer from noise increasing inversely proportional to frequency (1/f), our results show that this effect is not enough to impair the detection of the thermal oceanic signatures at the frequencies here considered.…”

High resolution seafloor thermometry for internal wave and upwelling monitoring using Distributed Acoustic Sensing

“…This also implies that, at long distances, DTS measurements need to be averaged over longer times (tens of minutes or more) and over larger gauge lengths to achieve acceptable performances [92]. In contrast, the Rayleigh scattered power is 20 to 30 dB higher than the Brillouin and Raman scatterings typically used for temperature sensing, respectively [93], so that longer sensing ranges are attainable with DAS (up to 100 km and more [94]). At the same time, diverse techniques exist to preserve optimal DAS repeatability at long distances [21].…”

“…When implemented, the SMART cable initiative [97] should provide calibrated temperature sensors at the optical repeaters of new cables. It is also worth reminding the significant efforts and recent progress on the improvement of the sensing range, SNR characteristics and the simultaneous use of DAS instruments on operating telecommunication fibers [21,94,98,99,100,101,102]. Although…”

Fast-recovering phi-OTDR system based on multi-sideband pulse modulation

“…But they don't consider the potential hardware burden resulting from increased data volume when conducting large-scale detection with high sampling rate. There have been attempts to use hardware circuits such as FPGAs (Field-Programmable Gate Arrays) and corresponding algorithm networks for data processing to achieve fast detection response [13,14]. While some parts of the demodulation process have seen significantly reduced processing time, there is still a tradeoff between FPGA resources and the amount of system probe data.…”