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DXD/PTP/GPS User Manual (rev 2.10)
3. Reference & Sync Menus
3.1 REFERENCE MENU (MENU 1.1)
Two new choices are available for reference selection based on the installed options: GPS and PTP Mode.
GPS is straightforward, like the other references available to the DXD-8. When selected, it becomes the DXD reference. If GPS
reception drops out, the DXD will switch to internal crystal until GPS reception resumes. The transition occurs smoothly to avoid
sync shocks.
When using GPS, it is recommended to install the optional OCXO oscillator for better tracking during long dropouts (see ch 7).
PTP Mode is a little different. Selecting PTP Mode as the reference is required for the DXD-8 to be a PTP slave, i.e. 'referenced'
to a PTP Grandmaster. However, selecting PTP Mode means that the DXD-8 will participate in the PTP Grandmaster selection and
will either be a PTP Slave or the Grandmaster based on the outcome of the BMCA (see 3.5). Explanatory text has been added to
the REFERENCE menu when PTP Mode is activated.
NOTE: When PTP Mode is selected, the PTP port needs to be turned on (menu 5.1). If not,
the DXD-8 will lock to its internal crystal and a 'PTP NO PORT' warning message will appear
in the middle of the display. The LOCK bar at the bottom of the Main Rotation display will
also indicate NO PORT (for more information, see chapter 22.Troubleshooting).
• LOCAL REF WHEN GM:
When PTP Mode is selected , if GPS is available, this fields enables GPS to be set as the reference when the DXD-8 is the Grandmaster.
Enabling this field will announce the DXD-8 as GPS referenced, giving it a better chance at being selected by the BMCA.
This field only appears if the optional DXD/GPS receiver has been installed.
3.2 SYNC PARAMETERS (MENU 1.2)
New parameters are available in this menu with the PTP or GPS options.
• BNC INPUT TIME JAM SOURCE: Selects the source of a Time Jam (see 8.2).
• BNC INPUT TIME JAM RESYNC: Used for a manual Time Jam (see 8.2)
• PTP JUMP THRESHOLD: When the difference between the internal TOD and the PTP reference is above the value
entered, the DXD will not attempt a smooth transition (slew) but will instead jump instantly to the new time.
Value can be adjusted from 5 msec to 15 sec, or set to 'Never'. Default value is 5 msec.
4. PTP Menus
4.1 PORT MODE (MENU 5.1)
This menu allows you to have PTP turned on or off.
• When OFF, PTP is disabled (default value).
• When ON, the port is enabled.
With the port enabled, the DXD-8 automatically becomes a candidate for PTP Grandmaster. Keep in mind however that it's
ability to be a PTP slave depends on the reference selection in menu 1.1:
NOTE: When the port is enabled and a reference other than 'PTP Mode' is selected menu 1.1, if the BMCA selects another
unit as PTP Grandmaster, the port will go in the PASSIVE state.
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if PTP Mode is selected: the DXD-8 can become a PTP slave.
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if another reference is selected: the DXD-8 can only be a PTP master, not a PTP slave.
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