A Network Time Interface M-Module for distributing GPS-time over LANs

This paper provides a comprehensive overview of our Network Time Interface (NTI) M-Module, which facilitates high-accuracy time distribution in LAN-ba sed distributed real-time systems. Built around our custom UTCSU VLSI chip, it hosts all the hardware support required for interval-based external clo ck synchronization: A high-resolution state- and rate-adjustable clock, loc al accuracy intervals, interfaces to GPS receivers, and various timestampin g features. Maximum network controller and CPU independence ensures that th e available NTI prototype can be employed in virtually any COTS-based syste m with MA-Module interface. Our experimental evaluation shows that time dis tribution with mu s-accuracy is possible even in Ethernet-based system arch itectures, provided that the available configuration parameters are suitabl y chosen to cope with the various hidden sources of timing uncertainty.