Airspan AS4000 User manual

605-0000-428 Airspan Communications Corporation
Issue 1.2 Date 5/11/98
AS4000
Wireless Local Loop System
Central Terminal
Level Control Unit
Operators Manual

Central Terminal Level Control Unit
Operators Manual Preface
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Central Terminal Level Control Unit
Operators Manual Preface
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Notice
1. This manual is subject to revision.
2. All rights reserved.
3. Right of modification reserved.
4. This manual is supplied without liability for errors or omissions.
5. No part of this manual may be reproduced or used except as authorised by contract or
other written permission.
6. This equipment is conditioned by the requirement that no modifications are made to the
equipment unless the changes or modifications are expressly approved by the Airspan
Communications Corporation
7. Prerequisite skills: Personnel installing, commissioning, and maintaining the Airspan
products must have a basic knowledge of telephony and radio communications, and have
experience in installing, commissioning and maintaining telecommunications products.
ACC provides a range of comprehensive training courses specifically aimed at providing
operators/users of Airspan products with the prerequisite skills to install, commission and
or maintain the product. The courses are tailored to provide the level of training required
by the operator/user.
8. Airspanand Sitespanare Registered Trademarks of Airspan Communications
Corporation.
For additional information on Airspan Systems, please call your ACC Representative, or
contact ACC at: Cambridge House
Oxford Road
Uxbridge
Middlesex
UB8 1UN
Call (44) 895 4677100

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Safety Instructions - Warnings and Cautions
SAFETY
1. Read and follow all warning notices and instructions marked on the product or included in
this manual
2. Do not allow anything to rest on the power cord and do not locate the product where
persons could step or walk on the power cord.
3. When installed in the final configuration, the product must comply with the applicable
Safety Standards and regulatory requirements of the country in which it is installed. If
necessary, consult with the appropriate regulatory agencies and inspection authorities to
ensure compliance.
4. No hazardous RF radiation is emitted from the equipment.
WARNING - HAZARDOUS VOLTAGES
On AC installations, hazardous voltages exist. Use caution when verifying or working with
AC power. Remove metal jewellery that could come into contact with AC power.
On DC sections, short circuiting the low voltage, low impedance circuits can cause severe
arcing that may result in burns or eye damage. Remove rings, watches etc. to avoid shorting
DC circuits.
Electro-Static Discharge ESD
Electro-Static Discharge. Many circuits contain devices which are susceptible to damage
from high impedance voltage sources. To avoid such risks always follow anti-static
procedures where marked.

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NOTE
Airspan products do not contain hazardous substances (as defined in UK ‘Control of
Substances Hazardous to Health Regulations 1989’, and the ‘Dangerous Substances
Regulations 1990’). At the end of any Airspan product’s life cycle, the customer should
consult with ACC to ensure that the product is disposed of in conformance with the relevant
regulatory requirements
The Symbol on an Airspan product signifies that it has been certified according to the
EMC directive 89/336/EEC. The product fulfils the requirements according to the following
standards:
EN50082-1 for Immunity.
EN55022 Group 1 Class A for the Central Terminal Emissions.
EN55022 Group 1 Class B for the Subscriber Terminal Emissions.
NOTE
The Subscriber Terminal equipment has been tested and found to comply with the limits for a
Class B digital device, pursuant to part 15 of the FCC Rules.

Central Terminal Level Control Unit
Operators Manual Preface
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Issue 1.2 Date 5/11/98
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User Response Form
Mail: Airspan Communications Limited Fax: [phone]
Cambridge House
Oxford Road
Uxbridge
Middlesex
UB8 1UN
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Thank you for your co-operation and assistance.

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Central Terminal Level Control Unit
Operators Manual ICL 001
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Page 1 of 2 © Copyright Airspan Communications Corporation 1998
ISSUE CONTROL LIST
Title Issue Date Issue Details
Title Page 1.2 November 1998 Issue
ICL-001 1.2 November 1998 Issue
IXL-001 1.2 November 1998 Issue
GSI-001 1.2 November 1998 Issue
DLP-001 1.2 November 1998 Issue

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CHANGE TYPE/DATE PURPOSE PAGES AFFECTED
Draft Issue #, Month
Year

Central Terminal Level Control Unit
Operators Manual IXL 001
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INDEX TASK LIST
PREFACE:
Safety Instructions Warnings and Cautions
User Response Form
ACCESS: ICL, IXL
Issue Control List ICL-001
Index Task List IXL-001
GENERAL SYSTEM INFORMATION: GSI
Introduction.GSI-001
1. Purpose of Document..................................................................................................1
2. Prerequisite skills........................................................................................................1

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Abbreviations
AC Alternating Current
AGC Automatic Gain Control
CPE Customer Premises Equipment
CRU Customer Radio Unit
CT Central Terminal
DC Direct Current
DMM Digital Multi Meter
DRS Digital Radio System
ISDN Integrated Services Digital Network
ITU-T International Telecommunications Union -Telecommunications
LD Loop Disconnect
LED Light Emitting Diode
MF Multi-Frequency
NTU Network Termination Unit
PC Power Control
PSU Power Supply Unit
RF Radio Frequency
ST Subscriber Terminal
Rx Receive
Tx Transmit
VDU Video Display Unit
VF Voice Frequency

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Related Documentation
Fixed Assignment
605-0000-430 System Overview
605-0000-431 System Operations and Maintenance Manual
605-0000-432 Central Terminal - Equipment Rack Installation & Commissioning
605-0000-433 Central Terminal - Antenna/Feeder Installation & Commissioning
605-0000-434 Hardware Overview
605-0000-435 Material Return and Repair
605-0000-436 Subscriber Terminal Installation & Commissioning
605-0000-437 D128 Terminal Converter
Demand Assignment
605-0000-450 System Overview
605-0000-451 System Operations and Maintenance Manual
605-0000-452 Central Terminal - Equipment Rack Installation & Commissioning
605-0000-453 Access Concentrator - Equipment Rack Installation & Commissioning
605-0000-454 Subscriber Terminal Installation & Commissioning
605-0000-427 Sitespan

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Central Terminal Level Control Unit
Operators Manual GSI 001
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Page 1 of 2 © Copyright Airspan Communications Corporation 1998
INTRODUCTION
1. Purpose of Document
This document describes the operation of the ACC (CT) Rack Level Control Unit
2. Prerequisite skills
This manual is intended for use by persons familiar with the Airspan product having
attended the ACC CT training course prior to performing the procedures in this
practice.

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Central Terminal Level Control Unit
Operators Manual GSI 002
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LEVEL CONTROL UNIT
1. Introduction
The Level Control Unit (LCU) is used during system commissioning and routine
maintenance. The Unit can be used to commission the Central Terminal, and set to
poll each modem shelf hourly or daily to ensure the receiver setting is at its optimum.
One Level Control Unit may be shared by up to four modem shelves in a single rack.
2. Architecture Overview
The Level Control Unit architecture as depicted in Figure 1. Components comprise;
i. A rack mounted Level Control Unit
ii. Cables and couplers to allow the Level Control Unit to be connected to the RF
sub-system.
iii. Cables to allow the Level Control Unit to be connected to each Modem Shelf
(to support communications to each Shelf Controller).
iv. Associated system firmware upgrades required to support AGC operation in
cards such as the Shelf Controller.
The following 'channel configuration' data is entered for each dependent modem
shelf;
•Coupler, cabling and LCU losses, Note: These components are labelled to show
insertion loss.
•Mode setting for each Shelf Controller i.e. Continuous mode, hourly poll, daily
poll, automatic level control suspended.
Other channel configuration data such as frequency and PN code is automatically
extracted from each shelf controller.

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Level Control Unit
Modem Shelf 1
Modem Shelf 2
Modem Shelf 3
Modem Shelf 4
RF Combiner Shelf
Antenna
Port 1
Coupler
Shelf
1 & 2 Tx
1, 2, 3, 4 Rx
Shelf
3 & 4 Tx
‘B’
Communication lines to
each shelf controller
Includes keypad and display for user I/O
Digi Board
Sitespan PC
Antenna
Port 2
Coupler
or
X25 PAD
To
Element
Manager
Figure 1. LCU Connections to AS4000 CT Rack

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3. Principles of Operation
The Level Control Unit periodically acquires a full low rate RF downlink /
uplink through RF cabling coupled into the CT transmit / receive antenna
ports. Knowledge of the path loss between the Level Control Unit and RF
antenna port allows the LCU to instruct the Shelf Controller to adjust RF
receive level as required.
The alpha-numeric display using menu driven selections with the keypad
provides:
•Input and read-back of set up information regarding RF component losses,
frequency, PN code.
•Output information on the Level Control Unit status and the status of each
RF channel.
To allow a specific RF channel to be quickly adjusted during commissioning
(or re-checked by a visiting maintenance engineer) a “continuous mode” of
operation (selected using the handheld terminal) enables downlink
transmission on the code specially allocated for gain adjustment purposes. The
Level Control Unit scans and acquires a CDMA link, status information such
as confirmation of control loop convergence is displayed. Once control loop
convergence has been confirmed the Shelf Controller mode is set to “Polled
Mode”by the operator for normal background control of the receiver gain of
each RF channel. Polled Mode settings of once per hour or once per day are
supported
Note 1: If the LCU is left in continuous mode for more than 1 Hour, the shelf
controller will disable the downlink to prevent the LCU using the radio
channel indefinitely.
Note 2: The transmission of the CDMA code signal for the link to the Level
Control Unit from each Modem shelf is supported using Modem number 16
which is also used to provide automatic Modem sparing. If the circumstances
exist that the spare modem is required to function in place of a faulty modem,
the automatic receiver gain control is suspended for that modem shelf until
Modem 16 becomes free again.

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4. Level Control Unit
4.1. Mechanical
The Level Control Unit is fitted at the base of the Central Terminal Rack and
measures 600mm wide, 300mm deep. 100mm high.
1
Dip/
LNA
TX
Filter
DC In
1 1
1
1
237
Shelf 4 Shelf 1
Shelf 3 Shelf 2
Terminal
OKFRU Fail
Front
Left Side Right Side
AB
4.2. RF Interconnect
The Level Control Unit has two RF ports (SMA connectors 50 Ohm
impedance) and is connected to the RF antenna port using one length of RF
cable and one coupler per antenna port. Unused ports are terminated using 50
ohm RF loads. All couplers and cables are marked to show insertion loss.
4.3. Shelf Controller Communications
On CT racks cables with 25pin D type adapters allow communication from the
management system port of each modem shelf to the Level Control Unit. A
female 25 pin D type connection is presented on the adapter for connection to
the Sitespan Management system.
4.4. DC Connections
The DC Supply is connected to a 15 way D-type connector on the right side of
the unit. The Battery return is connected to pin 4 and duplicated supplies to
Batt-ve(0) to pin 8 and Batt-ve(1) to pin 7 .
4.5. Handheld Terminal
A handheld terminal is used as the man-machine interface for the Level
Control Unit. This interface is menu driven and the number of data entries are
kept to the absolute minimum to reduce the software complexity.