User Manual

Chapter 4 - Operation and Administration Using the CLI NPU Configuration
4Motion 433 System Manual
4.3.14.2 Configuring the GPS
The GPS is used to synchronize the air link frames of Intra-site and Inter-site
located sectors to ensure that in all sectors the air frame will start at the same
time, and that all sectors will switch from transmit (downlink) to receive (uplink)
at the same time. This synchronization is necessary to prevent Intra-site and
Inter-site sectors interference. In addition, the GPS synchronizes frame numbers
that are transmitted by the AU.
The GPS clock generates a 1PPS signal with accuracy of 10
-11
and maximum jitter
of 100ns, and is connected to the 4Motion shelf via the GPS SYNC IN connector on
the front panel of the NPU. The GPS clock requirements can be reached by an
outdoor installed GPS unit when it is synchronized to a minimum number of
(user-configurable) satellites.
This section describes the commands to be used for:
 “Configuring the GPS Clocks” on page 434
 “Configuring General Configuration Parameters for the GPS” on page 437
 “Configuring the Date and Time” on page 439
 “Configuring the Position” on page 440
Syntax
Description
Parameter Description Presence Default
Value
Possible
Values
<slot id
(1-2)>
Indicates the PIU slot ID for
which the hardware version is
to be configured.
Mandatory N/A 1-2
hw_version
<version
(0-7)>
Indicates the hardware
version to be configured for
the PIU slot.
Mandatory N/A 0-7
Command
Modes
Global configuration mode
IMPORTANT
Implementation of GPS synchronization is based on the assumption that all sectors are operating with
the same frame size and with the same DL/UL ratio.