Time

Boreas is designed to provide a highly accurate time reference via an internal oscillator.

The oscillator is a temperature compensated disciplined oscillator.

For a device with a GNSS receiver, when GNSS fix is available the internal oscillator uses GNSS time to precisely correct itself within an accuracy of 20 nanoseconds.

When the GNSS fix is lost, the time will slowly lose accuracy.

When Boreas hot-starts, time accuracy is typically achieved within 1-2 seconds after a GNSS fix is achieved.

The time can be accessed via the following means:

• A dedicated 1PPS Signal. This is the preferred means to obtaining the most accurate timing output.

• A 1PPS output over GPIO or the Auxiliary port, see 1PPS Output of the Dynamic Pin Functions.

• A built-in Precision Time Protocol (PTP) version 2 server for synchronisation with network-connected devices which require high accuracy time. The PTP server broadcasts PTP messages (Sync, Follow Up, Announce) to multicast IP address 224.0.1.129. The PTP broadcasts are sent whenever an Ethernet connection is established and cannot be disabled.
  
  - PTP version: 2, generic profile
  - Master output: UDP multicast
  - Clock sync: 2-step (1-step used as fallback if necessary)
  - 1PPS output: Internal clock / GNSS
  - Protocol: IEEE 1588
  - Delay mechanism: E2E (delay request-response)

• A built-in Network Time Protocol (NTP) server.