Timing in Private Digital Telecommunication Networks

J.E. Abate, C.D. Near, M.S. Russo

Abstract: For proper operation of today's large digital private networks, high quality synchronization must be achieved. A general telecommunication performance objective is to maintain long-term frequency accuracy of ten parts per trillion at all synchronous digital equipment in the network. Many times, however, this is not achieved in private networks. Low quality clocks, errored transmission facilities, and incorrectly designed synchronization plans am often cause for poor performance. It is shown that properly-designed private networks can operate with long term frequency averages between ten parts per trillion to ten parts per million. These performance levels can adversely impact customer applications. The most demanding applications are digital and voiceband data, encrypted voice, facsimile and video. In a typical private network operating at 0.01 parts per million, the user would experience reduced data throughput, dropped encrypted calls, unreadable facsimile pages, or interrupted video transmission kens of times per day. The major contribution to poor private network synchronization performance is the interaction of Customer Premises Equipment (CPE) clocks and the network facilities used to distribute timing. The performance of typical CPE clocks and facilities, and their impact on customer applications, are discussed. CPE clock performance issues, along with private network architectural constraints, make synchronization planning extremely difficult. Planning is usually costly and requires specialized expertise.
Published in: Proceedings of the 24th Annual Precise Time and Time Interval Systems and Applications Meeting
December 1 - 3, 1992
Ritz-Carlton Hotel
McLean, Virginia
Pages: 327 - 336
Cite this article: Abate, J.E., Near, C.D., Russo, M.S., "Timing in Private Digital Telecommunication Networks," Proceedings of the 24th Annual Precise Time and Time Interval Systems and Applications Meeting, McLean, Virginia, December 1992, pp. 327-336.
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