Backplane Bus Distributed Realtime Clock Synchronization

This report presents methods of synchronizing the realtime clocks associated with a set of respective digital processing modules interconnected through a backplane bus. All the methods are based on the broad cast of a strobe signal over the backplane bus, which simultaneously samples all the realtime clocks being synchronized. The report describes and compares various methods of implementing realtime clocks, designed to permit their rate of advance with respect to physical time to be adjusted. It examines and makes recommendations on various interface standardization issues related to variable rate realtime clocks. It also gives and evaluates software algorithms for synchronizing variable rate realtime clocks.