22 February 2017 Coherent optical time domain reflectometry by logarithmic detection and timed random frequency hopping
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Abstract
A scheme using timed random frequency hopping and signal logarithmic mean method is proposed and experimentally demonstrated in a coherent optical time domain reflectometry (OTDR) system to reduce the fading noise of the OTDR trace and simplify the signal processing procedure. The timed random frequency hopping is realized by randomly changing the driving current of the laser at certain time points. By this method, the fading noise of OTDR trace can be reduced to be 1 / 5 of that without using it. Also, a radio frequency power detector (RFPD), whose output voltage has linear relationship with the input logarithmic RF power, is used to extract the power of the RF signals from the balanced photodetector. Then, a data acquisition card directly captures and adds the digital voltage signals from the RFPD to reduce the fading noise and improve the measurement dynamic range. Compared with synchronous and asynchronous frequency hopping scheme, the proposed method is of high efficiency.
© 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
Lidong Lu, Xiaoyan Sun, Xiande Bu, Binglin Li, "Coherent optical time domain reflectometry by logarithmic detection and timed random frequency hopping," Optical Engineering 56(2), 024106 (22 February 2017). https://doi.org/10.1117/1.OE.56.2.024106 . Submission: Received: 15 August 2016; Accepted: 6 February 2017
Received: 15 August 2016; Accepted: 6 February 2017; Published: 22 February 2017
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