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Word timing recovery in direct detection optical PPM communication systems with avalanche photodiodes using a phase lock loopA technique for word timing recovery in a direct-detection optical 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 833-nm AlGaAs laser diode transmitter and a silicon avalanche photodiode photodetector, and it used Q = 4 PPM signaling at source data rate 25 Mb/s. The mathematical model developed to describe system performance is shown to be in good agreement with the experimental measurements. Use of this recovered PPM word clock with a slot clock recovery system caused no measurable penalty in receiver sensitivity. 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 to the -6th at less than 60 average detected photons per information bit.
Document ID
19900056107
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Sun, Xiaoli
(Johns Hopkins Univ. Baltimore, MD, United States)
Davidson, Frederic M.
(Johns Hopkins University Baltimore, United States)
Date Acquired
August 14, 2013
Publication Date
May 1, 1990
Publication Information
Publication: IEEE Transactions on Communications
Volume: 38
ISSN: 0090-6778
Subject Category
Communications And Radar
Accession Number
90A43162
Distribution Limits
Public
Copyright
Other

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