Title :
Word timing recovery in direct detection optical PPM communication systems with avalanche photodiodes using a phase lock loop
Author :
Sun, Xiaoli ; Davidson, Fredric M.
Author_Institution :
Dept. of Electr. & Comput. Eng., Johns Hopkins Univ., Baltimore, MD, USA
fDate :
5/1/1990 12:00:00 AM
Abstract :
A technique for word timing recovery in a direct detection optical pulse position modulation (PPM) communication system is described. It tracks on back-to-back pulse pairs in the received random PPM data sequences with the use of a phase locked loop. The experimental system consisted of an AlGaAs laser diode transmitter (λ=833 nm) and a silicon avalanche photodiode photodetector, and its used Q=4 PPM signaling at a source data rate of 25 Mb/s. The mathematical model developed to characterize system performance is shown to be in good agreement with the experimental measurements. Use of this recovered PPM word clock, along with a slot clock recovery system described previously, caused no measurable penalty in receiver sensitivity when compared to a receiver which used common transmitter/receiver clocks. The completely self-synchronized receiver was capable of acquiring and maintaining both slot and word synchronizations for input optical signal levels as low as 20 average detected photons per information bit. The receiver achieved a bit error probability of 10-6 at less than 60 average detected photons per information bit
Keywords :
III-V semiconductors; aluminium compounds; avalanche photodiodes; clocks; elemental semiconductors; error statistics; gallium arsenide; optical communication equipment; phase-locked loops; photodetectors; pulse position modulation; receivers; semiconductor junction lasers; silicon; 25 Mbit/s; 833 nm; AlGaAs laser diode transmitter; Si; Si APD photodetectors; avalanche photodiodes; back-to-back pulse pairs; bit error probability; direct detection optical PPM communication systems; phase lock loop; received random PPM data sequences; receiver; recovered PPM word clock; word timing recovery; Clocks; Optical detectors; Optical modulation; Optical pulses; Optical receivers; Optical sensors; Optical transmitters; Pulse modulation; Timing; Tracking loops;
Journal_Title :
Communications, IEEE Transactions on