Configure Time of Day (ToD) distribution

Procedure 8-4: Configure Time of Day (ToD) distribution

Overview

Use this procedure to provision Time of Day (ToD) related parameters for a VLNC62 circuit pack.

The ToD signal is received via a GPS input signal and an associated 1 PPS signal. It is distributed to remote nodes using ptp-1588 timing.

Accurate ToD distribution is a critical requirement in mobile backhaul networks. These networks require stringent timing synchronization between base station and remote sites and among various remote sites.

ToD provisioning guidelines

When the ToD mode parameter is enabled the following guidelines apply:

Both ToD and clock frequency are distributed in this mode. However, for applications requiring an accurate ToD, it is recommended to use SyncE timing for distribution of clock frequency.
If the system is in ptp-1588 timing Master mode, 1588 SYNC messages are transmitted only when there is a valid GPS input.
If the system is in ptp-1588 timing Master mode and there is loss of GPS input (or change of GPS input signal state to DNU), the system continues to send SYNC messages.
If the system is in ptp-1588 timing Slave mode and there is loss of GPS input (or change of GPS input signal state to DNU) the recovered frequency/time on the system might drift over period of time due to lack of recalibration on the Master.

When the ToD mode parameter is disabled the following guidelines apply:

In ptp-1588 timing Master mode, 1588 SYNC messages are transmitted even without GPS input.
In ptp-1588 timing Slave mode, the 1 PPS signal will be shut off. The GPS message will not be output as well.

If the ToD parameter is disabled on the Master and enabled on the Slave, the ToD Summary screen may not reflect the actual ToD status of the circuit pack

When the ToD mode parameter is changed, the ptp-1588 timing must be restarted.

Step


1	Log in to the VLNC62 circuit pack being provisioned.
2	From the Navigation menu, select Timing → Time of Day → ToD Configuration. Result: The ToD Configuration screen appears.
3	Enter the required parameters, then click Submit. Parameters include: ToD Mode: Enable or disables the ToD capability on the circuit pack. Delay Compensation: Specifies the delay compensation value (in nanoseconds) on the VLNC62 circuit pack. This is required to offset delays caused due to cabling from the GPS receiver to the ToD input port. It may also be required to offset delays among different ToD receiving ports driven by the same GPS source.
4	From the Navigation menu, select Timing → Time of Day → ToD Summary and verify that the required parameters are provisioned correctly. Result: The ToD Summary screen appears. End of steps