Distributed Temperature Sensing Using Cyclic Pseudorandom Sequences

An alternative for commercial Raman-Optical Time Domain Reflectometry (OTDR) distributed temperature sensors is presented, where a pseudorandom pulse sequence is used to increase the signal to noise ratio. Additionally, a deconvolution algorithm is proposed to eliminate distortions in the reconstruction arising from the real correlation properties of the sensing signal. An improvement in SNR of a factor 11 respect to the Raman-OTDR method at the same peak power was achieved, allowing 2 m and 1.5 °C resolution in a 6 s measurement using a 90-mW Continuous wave semiconductor laser.