A noise-gated PLL for clock recovery in a free-space laser communication system

Abstract

In this thesis, I developed a phase-locked loop system for data clock recovery in a free-space laser communication application. The clock recovery unit is designed to operate at extremely low optical received power, tolerate a fading channel, and also account for Doppler effects. I explored the feasibility of adding a noise-gating system to the clock recovery unit in order to improve link margin in low-data-rate scenarios. I measured key system performance metrics, such as bandwidth, rejection, lock range and phase noise, and tested system integration with the existing optical communications testbed.