An OLTS is a mainstay for testing fiber optic cabling because it provides the most accurate method for determining the total loss of a link. An OLTS includes a light source. Both TIA and ISO standards use the term “Tier 1” to describe testing with an OLTS. An OTDR characterizes the loss of the link for individual splices and connectors by transmitting light pulses into a fiber and measuring the amount of light reflected from each pulse. Whether in telecommunications, data centers, or photonics applications, insertion loss testing ensures systems operate with minimal signal. This Applications Engineering Note (AEN 135) explains and recommends standard measurement methods for characterizing optical fiber system performance. An automated, highly precise OLTS that does all the hard work for. EXFO's MaxTester 945 Telco OLTS is a tablet-inspired OLTS that measures at two wavelengths, conducting IL, ORL and length measurements in 5 seconds.