Two signal processing enhancements for optical time domain reflectometry

Because time domain response of the backscattered signal in optical fibers is essentially exponential, there is 6-8 dB signal gain obtainable by using a logarithmic amplifier before any form of averaging, in the weak signal limit. Furthermore, the direct summation averaging of noisy traces (instead of the usual weighted averaging) is simpler because the required OTDR information is essentially relative.