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Proceedings Paper

Surface Acoustic Wave (SAW) Technology For Clock Recovery In The Fiber Distributed Data Interface (FDDI)
Author(s): Michael R. Slawson
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Paper Abstract

This paper describes the use of Surface Acoustic Wave (SAW) technology for clock recovery, and the performance of this technology in the Fiber Distributed Data Interface (FDDI) draft standard. FDDI, because it operates at 125 MBd over the fiber optic media, requires tight control of the jitter accumulated in each point-to-point fiber link. The clock recovery function must be able to recover the clock and correctly sample the bit stream, given a relatively narrow "eye opening" at its input. Furthermore, the clock must be maintained during the FDDI "line states," which can have a very low transition density. This paper will first describe the particular implementation of SAW technology used for clock recovery, the SAW filter, and will define it purpose within the clock recovery function. Then, the jitter characteristics of the FDDI signal at the input to clock recovery, as well as the performance of the SAW-based clock recovery function under these input conditions, will be discussed. Experimental results obtained using a typical, Commercially available, SAW filter-based module will be presented. The various "detuning" sources of the SAW filter, which detract from the capability of the SAW-based module to perform accurate sampling, will be discussed. The performance of the module under FDDI line state conditions, particularly Master Line State (MLS) and Quit Line State (QLS), will be analyzed. The QLS, which indicated a disabled upstream transmitter or a cable break, contains no transitions and therefore no information for clock recovery. A circuit will be presented which uses the station's local oscillator and the "signal detect" function of the fiber optic receiver to derive the recovered clock in the event of QLS.

Paper Details

Date Published: 1 January 1987
PDF: 6 pages
Proc. SPIE 0841, Fiber Optic Networks and Coherent Technology in Fiber Optic Systems II, (1 January 1987); doi: 10.1117/12.967566
Show Author Affiliations
Michael R. Slawson, Siecor Electro-Ontic Products (United States)

Published in SPIE Proceedings Vol. 0841:
Fiber Optic Networks and Coherent Technology in Fiber Optic Systems II
John D. Chipman; Harish R. Sunak, Editor(s)

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