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-based distributed real-time systems. Built around our custom UTCSU VLSI chip, it hosts all the hardware support required for interval-based external clock synchronization: A high-resolution state- and rate-adjustable clock, local accuracy intervals, interfaces to GPS receivers, and various timestamping features. Maximum network controller and CPU independence ensures that the available NTI prototype can be employed in virtually any COTS-based system with MA-Module interface. Our experimental evaluation shows that time distribution with s-accuracy is possible even in Ethernet-based system architectures, provided that the available configuration parameters are suitably chosen to cope with the various hidden sources of timing uncertainty