טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentGoldman Renata
SubjectDirect Detection and Coherent Optical Time-Domain
Reflectometry with Single Pulses and Golay
Cmplementary Codes
DepartmentDepartment of Electrical Engineering
Supervisor Professor Moshe Nazarathy
Full Thesis textFull thesis text - English Version


Abstract

In this work, we theoretically and numerically model the Optical Time Domain Reflectometry (OTDR) technique based on repetitive single pulse transmission, including the mathematical simulation of the proposed models and evaluation of the results obtained.

We further consider the application of coding diversity, in particular, using complementary codes to improve the OTDR performance. This is realized, in this research, by extending the Golay complementary coded OTDR technique, which has successfully been applied to improve direct-detection OTDR performance, for the first time to coherent-detection OTDR. We investigate the unique issues arising in the coherent-detection setting regarding signal processing operations and efficient real-time implementation of the digital signal processing (DSP) in practical coherent-detection OTDR receivers and the resulting OTDR performance.

In addition, we have considered the application of frequency diversity to improve signal-to noise ratio (SNR) in OTDR systems, but concluded that this solution is equivalent to the single pulse implementation for a wide-band source (with total bandwidth equal to the sum of the bandwidths of the frequency diverse signals).

We also derive detailed signal flow block diagrams for direct-detection and coherent-detection OTDRs and use an intuitive analogy between spatial speckle and temporal coherent fading noise to guide us in the selection of OTDR system parameters.