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NETWORK BIT SYNCHRONIZATION ATOMIC CLOCK VERSUS FREQUENCY AVERAGING.
Final rept. 30 Aug 67-31 Jul 68,
MARTIN MARIETTA AEROSPACE ORLANDO FL
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This report describes the atomic clock and frequency averaging synchronization techniques, presents a comparison of these techniques, and offers conclusions on their applicability to the MALLARD system. Analytical results show that the expected magnitude and rate of reference frequency variations will not significantly affect the operation of the frequency averaging technique. The on-off and both-end control methods of implementing the frequency averaging techniques are discussed. There does not appear to be any advantage to the on-off method over the chosen continuous method. In both-end control, the system frequency is independent of link delays however, its increased complexity would be difficult to justify for use at all nodes, since for nonsatellite repeater nodes the single end method will satisfy the MALLARD requirements. The comparative evaluation discussed both techniques relative to the TGIM design, network synchronization loss and recovery and network performance. The relative operational characteristics of the candidate techniques are compared with particular emphasis given to their reliability, required power, maintainability, cost, size, and weight. This evaluation has indicated that the frequency averaging technique is more reliable and less costly to maintain than the atomic clock technique, primarily due to the complexity of the atomic standard. Comparisons of cost, weight, size, and power also favor the frequency averaging technique. The frequency averaging technique is sensitive to network structure or at least to changes in structure and therefore, the atomic clock technique is superior in this respect. Author
APPROVED FOR PUBLIC RELEASE