100 describes characteristics, construction, test methods, and performance criteria of optical fibre cables installed by pulling method for duct and tunnel application. Note that Recommendation ITU-T L. 10, Ed. Two of the key advantages of fiber optic linear heat detection (LHD) systems are based on the smart alarming functionality and the distributed nature of the measurements. With regards to the distributed. Distributed Temperature Sensing (DTS) systems provide temperature information for accurate thermal monitoring, fire detection, and condition assessment by utilizing standard fiber optic cables. The Raman backward scattering li y photo detectors.