User's Manual

Chapter 3 - Operation and Administration Using the CLI NPU Configuration

4Motion 385 System Manual

 External 16MHz: Generates all the main clocking signals in the system,

including the internal 1PPS clock. Using an external, accurate 16 MHz clock

source will enable better hold-over of the 1PPS clock upon temporary loss (or

reduced reliability when receiving less than 4 satellites) of the external 1PPS

clock. This will allow a longer time of continued operation before appearance of

interferences due to clock drifts among BSs. You can either enable the

external 16 MHz clock source or use the internal 16 MHz clock source. By

default, the external 16MHz clock is disabled. In the current release external

16MHz clock must be disabled.

To configure the GPS clock, run the following command:

npu(config)# set clock ([ External1PPS {Enable | Disable} ] [

External16MHz {Enable | Disable} ])

For example, to configure the internal 1PPS clock at the NPU to synchronize the

air frames for inter-site and intra-site sectors:

npu(config)# set clock External1PPS Disable

NOTE

If the external 1PPS GPS clock is enabled:

 The concatenated slave NPU 16Mhz created from local 16MHz TCXO/OCXO at the NPU

provides holdover when the GPS loses synchronization with its satellites.

 Configure the GPS parameters listed in section, Section 3.3.15.2.2.

IMPORTANT

Reset the system for changes in the GPS clock configuration to be applied to the entire system.

Command

Syntax

npu(config)# set clock ([External1PPS {Enable | Disable}] [External16MHz

{Enable | Disable}])

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