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Input Reference Priorities

NetClock can be synchronized to different time and frequency sources that are referred to as Input References, or just References.

References can be a GNSS receiver, or other sources such as NTP, PTP, IRIG, ASCII or HAVE QUICK time codes delivered into your NetClock unit via dedicated (mostly optional) inputs. It is also possible to enter a system time manually, which NetClock then can synchronize to.

Should you be installing new option cards, you will need to either manually set up the new card in the Reference Priority Table, or use the Restore Factory Defaults option in the Reference Priority Actions panel, in order to update the table with the new reference information.

In order for NetClock to declare synchronization, it needs both a valid 1PPS, and Time reference.

The concept of Reference Priority allows the ranking of multiple references for redundancy. This allows NetClock to gracefully fall back upon a lower ranking 1PPS or Time reference without transitioning into Holdover, in case a reference becomes unavailable or invalid. The priority order you assign to your available references typically is a function of their accuracy and reliability.

Note: The References shown on your screen may look different from the ones in the illustration below, depending on your NetClock Time Server model and hardware configuration.

Each available type of Time and 1PPS input reference is assigned a human-readable name or “title” that is used in the Reference Priority table, indicating the type of reference. The reference titles are listed in the following table:

Reference priority titles

Title Reference
ASCII Timecode ASCII serial timecode input
External 1PPS input External 1PPS input
Frequency External Frequency input
PTP PTP input
IRIG IRIG timecode input
Local System Built-in clock OR internal 1PPS generation
NTP NTP input
User Host (time is manually set by the user)

The number displayed indicates the number of feature inputs of that type presently installed in the NetClock– starting with “0” representing the first feature input. For example:

  • IRIG 0 = 1st IRIG input instance
  • Frequency 1 = 2nd frequency input instance
  • NTP 2 = 3rd NTP input instance

The columns of the Reference Priority table are defined as follows:

  • Priority—Defines the order or priority for each index (row). The range is 1 to 16, with 1 being the highest priority and 16 being the lowest priority. The highest priority reference that is available and valid is the reference that is selected.
  • Time—The reference selected to provide the necessary “Time” reference.
  • 1PPS—The reference selected to provide the necessary “1PPS” reference.
  • Enabled—The reference is enabled.
  • Delete—Removes the Index (row) from the Reference Priority table.