SPECIFICATION AND IMPLEMENTATION OF THE UNIVERSAL-TIME-COORDINATED-SYNCHRONIZATION-UNIT (UTCSU)

High-accuracy external clock synchronization can only be achieved with adequate hardware support. We analyze the requirements and present th e specification and implementation of an ASIC running under the acrony m UTCSU dedicated to that purpose. It is built around an elaborated lo cal clock, which is based on an adder driven by a fixed-frequency osci llator. This novel clock design allows a fine grained rate adjustabili ty apt for maintaining both local time with linear continuous amortiza tion and accuracy information as needed in interval-based clock synchr onization. Additional features incorporated in our UTCSU are facilitie s to timestamp clock synchronization data packets, interfaces to coupl e GPS receivers, some application support as well as sophisticated sel f-test machinery. Apart from addressing design and engineering issues of the chip, we also provide a basic programming model.