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Chapter 3 Indoor Equipment Maintenance
Redline Communications Inc. Confidential and Proprietary
Step 7
Click Status on the main menu to open the Status page. Verify that the SC Synchro
Status is Backup Master This confirms that this device is receiving the GPS clocking
pulse from the Master.
Configuring the Slave Sector Controller(s)
Step 1
Log into the sector controller and click Wireless Interface to verify the values of Frame
Duration (ms), Downlink ratio (%) and Cell Range (km). These values must be same on
all sector controllers that will be synchronized with the GPS clock.
Step 2
Set the Synchronization Mode to Slave.
Step 3
Click the Save button to save these changes
Step 4
Reboot the sector controller as outlined in “Rebooting the Devices” on page 3-2.
Step 5
Verify the successful restart and correct operation of the sector controller.
Step 6
Click Status on the main menu to open the Status page. Verify that the SC Synchro
Status is Slave.
Step 7
Verify that the device is receiving a clocking pulse on the Sync Out port. The event log for
the sector controller should log an event message "Master Detected" or “Synchronization
OK”. Review the event log as outlined in “Monitoring System Event Logs” on page 2-6.
Step 8
Repeat steps 1 through 7 for each of the remaining sector controllers at the base station
site.
All sector controllers will now be fully operational and time-synchronized from the GPS
satellite's clocking source.
AN100U/UX Operation in GPS Holdover
When the GPS clock’s input module is locked to a GPS signal, its internal oscillator and
memory function ensure the reference synchronization signal adheres to the “Timing
Characteristics of Primary Reference Clocks” standards (ITU-T recommendation G.811).
If the input module loses the satellite signal, the GPS clock goes into a holdover function
in which the 1PPS is provided by the GPS clock's internal oscillator. If the GPS clock
cannot re-acquire the satellite signal the GPS clock's internal oscillator can maintain time
accuracy for a few hours. The exact duration of the holdover period depends on the type
of GPS clock.
In order to notify you that the GPS clock has entered holdover, thirty (30) minutes after
entering holdover, the GPS clock receiver will temporarily suppress its 1PPS signal for 30
seconds (i.e. no signal). The AN100U/UX detects when the 1PPS signal stops and
restarts, and this is reflected in the event log and syslog. See Figure 3-1.
When the GPS clock goes into holdover, it tries to re-acquire the satellite signal. Whether
or not the GPS clock is able to re-acquire the satellite signal, there is no clear indication
to the RedMAX sector controllers. As far as the RedMAX sector controllers can determine,
a signal is being received on the Sync Out port. If the GPS clears holdover and is again
