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Page 6
5.3 ADVANCED GPS SETTINGS (MENU 6.3)
Menu 6.3 provides additional parameters, referred to as 'advanced', as, in most cases, they will not need to be modified and
are only provided for unusual situations requiring additional adjustments.
• Survey Sigma Threshold
Survey Sigma Threshold has a default value of 10. If your DXD/GPS is having difficulties in achieving lock, increase the
Sigma value.
• Survey Time Threshold
Survey Time Threshold is set by default to 24hrs. This survey time restarts each time the DXD is turned on. If you would
like to achieve lock faster, decrease the Time value.
6. Reference & Sync Menus
6.1 REFERENCE MENU (MENU 1.1)
• SOURCE:
-
OCXO: When selecting INTERNAL as the Reference Source and the OCXO option board has been installed, it will
be used automatically and the main DXD display will indicate 'Internal OCXO' in the Reference Line at the bottom
of the Main Rotation displays.
-
GPS: A new choice in the Source field when the DXD/GPS option is installed is GPS. GPS acts very much like Input
A or B. When selected in menu 1.1, it becomes the DXD reference. If GPS reception drops out, the DXD will switch
to internal crystal until GPS reception resumes. The transition occurs as smoothly as possible to avoid sync shocks.
When using GPS, it is recommended to install the optional OCXO oscillator for better tracking during long
dropouts.
• LOCAL REF WHEN GM:
If PTP is available and PTP MODE has been selected as the reference source, when GPS is
available, a new field appears in menu 1.1 enabling GPS to be set as the reference when
the DXD is the Grandmaster.
Enabling this field will announce the DXD as GPS referenced, giving it a higher priority at
being selected as Grandmaster by the BMCA.
6.2 SYNC PARAMETERS (MENU 1.2)
• BNC INPUT TIME JAM SOURCE:
In addition to PTP, GPS can also be selected as a Time Jam Source when the
selected reference is one of the two BNC Inputs. The sequence is similar to the Time
Jam to PTP. After the DXD has locked its internal Time of Day clock to GPS, it locks
to the BNC source selected in menu 1.1.
Note: Be sure the GPS Receiver is no longer in WARM UP state as it will not be
used for Time of Day in that condition.
NOTE: If GPS is selected as the reference while in WARM UP, the front panel will indicate a REF ERROR and
the DXD will switch to Internal (HOLD) until the GPS receiver has come out of WARM UP.
DXD/GPS/OCXO User Manual (rev 2.10)
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