Development and test of IEEE 1588 Precision Timing Protocol for ocean observatory networks

We report the development and testing of an IEEE 1588 precision timing protocol link for an undersea network application. The system provides clock synchronization between a dry-end Global Positioning system (GPS) timing receiver (a 1588 grandmaster clock) and multiple wet-end nodes (1588 clients or slaves) for the purpose of synchronized data acquisition, control, and data time stamps. The system consists of a distributed fiber optic Gigabit Ethernet network that will span approximately 200 km of seabed. The IEEE 1588 standard is discussed, as well as the protocol, the protocol algorithm, and various prototype architectures that were examined during design and development. These architectures included pure software implementations, pure firmware implementations, and mixed software-firmware designs. Tests and performance measurements on the various architectures are discussed, including accuracy of the network timing distribution and limitations of each approach. Potential improvements are also discussed for future undersea networks.