This part of IEC 61757 defines detail specifications for distributed temperature measurement
by a fibre optic sensor, also known as fibre optic distributed temperature sensing (DTS). DTS
includes the use of Raman scattering, Brillouin scattering and Rayleigh scattering effects. In
addition, Raman scattering and Rayleigh scattering based measurements are performed with
a single-ended fibre configuration only. Brillouin scattering based measurements are
performed with a single-ended fibre or fibre loop configuration. The technique accessible from
both sides at same time (e. g. Brillouin optical time domain analysis, BOTDA) is referred to
here as a loop configuration. Generic specifications for fibre optic sensors are defined in
IEC 61757-1:2012.
This part of IEC 61757 specifies the most important DTS performance parameters and defines
the procedures for their determination. In addition to the group of performance parameters, a
list of additional parameters has been defined to support the definition of the measurement
specifications and their associated test procedures. The definitions of these additional
parameters are provided for informational purposes and should be included with the sets of
performance parameters.
A general test setup is defined in which all parameters can be gathered through a set of tests.
The specific tests are described within the clause for each measurement parameter. This
general test setup is depicted and described in Clause 4 along with a list of general
information that should be documented based upon the specific DTS instrument and test
setup used to measure these parameters as per IEC 61757-2-2.
Annex A provides a blank performance parameter table which should be used to record the
performance parameter values for a given DTS instrument and chosen optical test setup
configuration.
Annex B provides guidelines for optional determination of point defect effects.