Reference Priorities: EXAMPLES

In this use case, the objective is to use:

• GNSS as the primary Time, and 1PPS reference
• IRIG as the backup Time, and 1PPS reference.

Step-by-step procedure:

1. Move the reference which has “GPS 0” in the Time column and “GPS 0” in the 1PPS column to the top of the table, with a Priority value of 1. Click the Enabled checkbox.
2. Move the reference which has “GPS 0” in the Time column and “GPS 0” in the 1PPS column to the top of the table, with a Priority value of 1. Click the Enabled checkbox.
3. Move the reference which has “GPS 0” in the Time column and “GPS 0” in the 1PPS column to the top of the table, with a Priority value of 1. Click the Enabled checkbox.

Since both of these references are default references, no additional references need to be added to the Reference Priority table.

In this use case, the objective is to use:

• IRIG as the primary reference input
• Another NTP server as backup reference

Step-by-step procedure:

1. Move the reference which has “IRIG 0” in both the Time column and “IRIG 0” in the 1PPS column to the top of the table, with a Priority value of 1. Click the Enabled checkbox.
2. Move the reference which has “NTP” in the Time column and “NTP” in the 1PPS column to the second place in the table, with a Priority value of 2. Click the Enabled checkbox.
3. For all other references, uncheck the Enabled checkbox, so that they are all disabled.

Since both of these references are default references, no additional references need to be added to the Reference Priority table.

In this use case, the objective is to have NTP provided by another NTP server as the only available reference input, i.e. the unit to be configured is operated as a Stratum 2 server. For more information, see Configuring "NTP Stratum Synchronization".

Step-by-step procedure:

1. Move the reference which has “NTP” in the Time column and “NTP” in the 1PPS column to the top of the table, with a Priority value of 1. Click the Enabled checkbox.
2. For all other references, uncheck the Enabled checkbox, so that they are all disabled.
3. Configure the NTP Service as described under Configuring "NTP Stratum Synchronization".

Note: When selecting NTP as an input reference, do not select another reference (such as GNSS, IRIG, etc.) to work with NTP as a reference. NTP should always be selected as both the Time and 1PPS input when it is desired to use NTP as an input reference.

Note: In order for a manually set time to be considered valid and used to synchronize VersaSync, a “User” needs to be created and enabled in the Reference Priority table. The "User/User" Reference.

In this use case, the objective is to use a hand-set time, in combination with VersaSync's oscillator as a 1PPS source as valid references.

Step-by-step procedure:

1. If necessary (see NOTE above), create a “User.”
2. Move the reference which has “User 0” in the Time column and “User 0” in the 1PPS column to the top of the table, with a Priority value of 1. Click the Enabled checkbox.
3. For all other references, uncheck the Enabled checkbox, so that they are all disabled.

If the objective is to use a manually set time as a backup to other references (such as GNSS or IRIG):

1. Move the "User/User" reference to a place in the table that has a priority lower than the references the "User/User" reference will be backing up. Make sure the Enabled checkbox is selected.
2. With “User/User” enabled, if no other higher priority references are enabled or available (or if the higher priority references have since been lost), you can now manually set the System time to the desired value (MANAGEMENT > OTHER: Time Management > System Time > Manual Time Set). See System Time for more information. VersaSync will go into synchronization using this set time once you click the Submit button.

Note: You will need to repeat this procedure each time VersaSync is power-cycled (with no other references available), unless you enabled the feature Synchronize to Battery Backed Time on Startup.

The objective of this use case is to allow VersaSync to use itself as a valid reference. This is referred to as “Local System” time.

In order for this to happen, VersaSync requires an external Time, or 1PPS reference. In other words, "Local System" cannot be both Time, and 1PPS. This makes "Local System" a legitimate, traceable reference.

Therefore the "Local System" does not have to be manually set ("validated") by the User after VersaSync was power cycled (as would be the case with a “User/User” reference).

Since “Local System” cannot be both Time, and 1PPS input together, in this example the GNSS input will be set as the 1PPS reference (other use cases may require using different references, e.g. IRIG.)

As there is no default entry for “Local System” and “GPS”, a new entry needs to be added to the Reference Priorities table in order to use this combination of references.

Step-by-step procedure:

1. Add a reference to the Reference Priority by clicking the PLUS icon. Use the following settings, then click Submit:
   • In the Priority Level text box, enter 1. This will give this reference the highest priority.
   • In the Time field, select “Local System”.
   • In the PPS field, select “GPS”.
   • Check the Enabled checkbox.
2. Confirm that the first reference in the Reference Priority table has “Local System” as the Time input and "GNSS" as the 1PPS input.
3. After a power cycle or reboot, as soon as GNSS is declared valid, the System Time will automatically be used as-is, with no manual intervention required.