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Slot clock recovery in optical PPM communication systems with avalanche photodiode photodetectorsSlot timing recovery in a direct-detection optical PPM communication system can be achieved by processing the photodetector output waveform with a nonlinear device whose output forms the input to a phase-locked loop. The choice of a simple transition detector as the nonlinearity is shown to give satisfactory synchronization performance. The rms phase error of the recovered slot clock and the effect of slot timing jitter on the bit error probability were directly measured. The experimental system consisted of an AlGaAs laser diode (wavelength = 834 nm) and a silicon avalanche photodiode photodetector. The system used Q = 4 PPM signaling and operated at a source data rate of 25 Mbits/s. The mathematical model developed to compute the rms phase error of the recovered clock is shown to be in good agreement with results of actual measurements of phase errors. The use of the recovered slot clock in the receiver resulted in no significant degradation in receiver sensitivity compared to a system with perfect slot timing. The system achieved a bit error probability of 10 to the -6th at a received optical signal energy of 55 detected photons per information bit.
Document ID
19900036473
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Davidson, Frederic M.
(Johns Hopkins Univ. Baltimore, MD, United States)
Sun, Xiaoli
(Johns Hopkins University Baltimore, MD, United States)
Date Acquired
August 14, 2013
Publication Date
November 1, 1989
Publication Information
Publication: IEEE Transactions on Communications
Volume: 37
ISSN: 0090-6778
Subject Category
Communications And Radar
Accession Number
90A23528
Distribution Limits
Public
Copyright
Other

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