S500 for Time Transfer

The Omnisense S500 System includes the capability of accurate time transfer between nodes in the network. This can be achieved to very high accuracy and, in the S534, node a physical clock pulse can be generated.

How Time Transfer is Achieved

Each S500 node operates from its own asynchronous clock. Nodes measure the time of arrival of signals from neighbours using their own local clocks as a reference.

When a node broadcasts its navigation signal (chirp), the data message contains information about itself including its estimated position, the time of the transmission based on its own clock and a subset of its neighbour observations.

Within the Omnisense JTLE (Joint Timing and Location Engine) sophisticated algorithms are used to track clock offsets between nodes and to compute the positions of the nodes.

In this way a highly accurate absolute time synchronised soft clock is established in each node.

Local Clock

Each node, therefore, has a free running unsynchronised local clock based on its internal low cost crystal oscillator, and a very accurate synchronised soft clock.

The soft clock may be used to generate a physical clock pulse (typically a pulse-per-second output similar to GPS). A low resolution pulse is available on the present S534 product. A very high precision pulse may be available in the future if applications demand.