Delta attenuation between the different loss of light intensity with distance for the Stokes and anti-Stokes Raman backscatter. This physical quantity requires careful calibration in order to set the correct slope of a DTS trace (DTS readings of a constant temperature do not change with distance).
Distributed Acoustic Sensor (DAS)
A sensor that allows for the collection of acoustic signal fully distributed along an optical fibre. The most advanced DAS systems allow for the collection of full-waveform acoustic data.
Distributed Temperature Sensor (DTS)
A sensor that allows for the collection of temperature data fully distributed along an optical fibre.
Change in frequency of a wave (or other periodic event) for an observer moving relative to its source.
A method of DTS measurement and calibration that requires an Optical Fibre in U shaped configuration. Each temperature trace is provided by combining two raw data traces measured sequentially from the two ends. Particularly useful for DTS calibration of multiple spliced and/or tight bended Fibre Optic Cables as it provides integrated differential attenuations in space. However, an extremely accurate measurement of the optical fibre length is necessary. It must not be confused with the duplex method.
A method of DTS measurement and calibration that requires an Optical Fibre in U shaped configuration. Single-ended measurements are performed sequentially from the two ends. Differently from double-ended method, the raw data traces are not combined.
Fibre Optic Cable
A complete assembled product including optical fibre(s), strength members, and protective jacket(s) that provides protection to the optical fibre(s) from environmental factors.
A method of joining two optical fibres end to end using intense heat. This method can provide connections with very low attenuation.
iDAS enabled flow meter
Real-time monitoring of multi-phase flow with Silixa’s iDAS
The light that is coupled into an optical fibre at the DTS and travels down the fibre from the near end toward the far end of the fibre.
Optical fibre that has a relatively large core diameter (when compared with singlemode fibre) of usually 50 or 62.5 µm. This type of fibre supports more than one light propagation mode.
Consisting of the core surrounded by the cladding, the optical fibre provides a means of transmitting signal at very high bandwidths over long distances through a process known as total internal reflection. Optical fibres are usually made of silica.
Passive distributed acoustic sensing
The use of distributed acoustic sensing in cases where the signal is comprised solely of naturally occurring acoustic signals.
The standard method of collecting temperature data along an optical fibre using DTS instrumentation, without artificially heating the fibre optic cable as in the active DTS methods.
Quantifies the smallest variation of a quantity that an instrument is able to detect and properly measure above the noise. For a DTS system, the smallest fluctuations in temperature that can be resolved. Precision can be used as synonymous of resolution, and is an index of the repeatability (in both space and time) of a measurement. It must not be confused with the accuracy. An instrument can be very precise, but still poorly accurate, and vice-versa.