YOKOGAWA DTSXL, User Manual, Page: 257 / 289

< PART – C Operation and Maintenance >
C-4
IM 39J06B40-01EN 14th Edition: May 30, 2022
C2. DTS-specific Operation and
Precautions
C2.1. Single-ended and Double-ended
Measurement
The DTSX3000 of the DTSXL System supports both single-ended and double-ended
distributed temperature measurement. In single-ended measurement, a light pulse is
launched from one end of the sensor optical fiber and the returned Raman scatter is
measured to determine temperature distribution. In double-ended temperature
measurement, a light pulse is launched from each of the two ends of the sensor optical
fiber and the returned Raman scatter is measured separately to determine temperature
distribution. This section describes the respective characteristics and precautions
relating to single-ended and double-ended measurements.
<Single-ended measurement>
<Double-ended measurement>
●
Single-ended measurement
Single-ended measurement can be used in distributed temperature measurement
applications where the sensor optical fiber cannot be looped back or no optical switch is
used.
Single-ended measurement is simpler than double-ended measurement but requires
correction for the differential sensor optical fiber loss between the Stokes light and anti-
Stokes light of the Raman scatter. The DTSX3000 uses the signal intensities of the
backscattered Stokes and anti-Stokes light in the sensor optical fiber for temperature
calculation. However, the Stokes and anti-Stokes light suffer different sensor optical fiber
loss due to their different wavelengths. The DTSX3000 corrects for this differential loss
in temperature calculation in single-ended measurement. The differential loss varies
between sensor optical fibers and thus needs be calculated beforehand and corrected
for in single-ended measurement.
SEE ALSO
For details on the temperature correction configuration, see Section B7.3.1., “Fiber Settings.”
Sensor optical fiber
Sensor optical fiber
Far end
Near end
Forward
Reverse