BSS Training_full

GSM-Global System for mobile communication: 

GSM-Global System for mobile communication After this course you will be able to Understand: Basic GSM System Model Understand the RBS Hardware overview. Understand the Cell Site Overview. BTS Logical(MO) Internal Tree. BSS Interface. Brief idea about the Command lines. Major reasons of the Network Failure. Brief System knowledge of Microwave.

PowerPoint Presentation: 

Some basic concepts of GSM 1.There are four frequency bands present in GSM i.e. 800,900,1800,1900 GSM 900 and GSM 1800 is used in most of the part of world as well as in INDIA also. b) GSM 1900 and 800 is specifically used in USA . These frequencies are used in USA becoz of the prior allocation of 900 band to diff. services.

PowerPoint Presentation: 

Basic components of GSM system. GSM system is divided into Two parts:- SS ( Switching Systems) BSS (Base Station Systems) SS components:- a) MSC b) HLR c) VLR d) GMSC e) AUC BSS Components:- BSC/TRC BTS MS is not a part any of Subsystem .

Brief Description of the GSM components: 

Brief Description of the GSM components 1)MSC (Mobile services Switching Centre) MSC performs the telephony switching functions for mobile n/w. It controls calls to and from other telephony and data systems such as PSTN,ISDN & other mobile N/Ws GMSC :- It connects one GSM N/W to other n/w. If a person wants to call from PSTN to a GSM mobile,then PSTN exchange will access the GSM N/W by 1 st connecting the call to a GMSC.Gateway functionality enables an MSC to interrogate a n/w HLR in order to route a call to MS. 2) HLR(Home Location Register) HLR is centralized N/W database that stores and manages all mobile subscriptions belonging to specific operator. It stores permanent subscription information of subscriber such as subs. Identity,supplimentary services,location information,authentication information etc. 3) VLR(Visitor Location register) VLR contains information about all the mobiles currently located in an MSC service area. Thus one VLR for each MSC in the N/W.It keeps the temporary information of all subscribers being served by that MSC.

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4) AUC (Authentication Centre) Its function is to authenticate the subscribers attempting to use network. 5) BSC (Base Station Controller) BSC manages all radio related functions of a GSM N/W. It is a high capacity switch that provides functions such as MS handover, radio channel assignment and collection of cell configuration data. 6) BTS (Base Transceiver Station) BTS controls the radio interface to MS.BTS comprises the radio equipment such as transceivers & antennas which are needed to serve each cell .A group of BTS controlled by BSC. 7) TRC (Transcoder Controller) TRC is to multiplex network traffic channels from multiple BSCs onto one 64kpbs PCM channel.

Types of BTS :-: 

Types of BTS :- Ericsson offers a wide range of BTS for GSM N/Ws:- Commonly used BTS types are as follows:- RBS2000 RBS2202 RBS2206 RBS2106 RBS2204 F) RBS2104 G) RBS2308

RBS 2106 Hardware overview: 

Y L I N K C X U CDU CDU CDU dTRU dTRU dTRU dTRU dTRU dTRU OMT Interface PCM A PCM B PCM C PCM D External Alarms (16) DXU 21 ESB (TG Sync) Mains Supply PSU BFU Batteries FCU Fans ACCU Air Conditioning AC Connection Box EPC Bus RBS 2106 Hardware overview

RBS 2206 Hardware overview: 

Y L I N K C X U CDU CDU CDU dTRU dTRU dTRU dTRU dTRU dTRU OMT Interface PCM A PCM B PCM C PCM D External Alarms (16) DXU 21 ESB (TG Sync) Mains Supply PSU BFU Batteries FCU Fans EPC Bus RBS 2206 Hardware overview

PowerPoint Presentation: 

RBS 2000 HARDWARE The RBS 2000 series is based on standardized hardware units called Replaceable Units (RU).The major RU’s are: (1) Distribution switch Unit (DXU) (2) Transceiver Unit (TRU) (3) Combining and Distribution Unit (CDU) (4) Power Supply Unit (PSU) (5) Energy Control Unit (ECU) Distribution switch Unit (DXU) The DXU performs the following tasks : (1) Provides an interface to the BSC (2) The Central Processing Unit (CPU) performs the resource management within the RBS2000 along with being responsible for the software loading of the TRUs.The CPU also provides the interface to the Operation and Maintenance Terminal (OMT) and the external alarms. (3) The Central Timing Unit (CTU) extracts synchronization information from the A-bis link and uses it to synchronize the base station timing with the network.Note that as an option the DXU can extract synchronization information from an external source such as a Global Positioning System (GPS).

PowerPoint Presentation: 

CXU-Configuration Switch Unit Frequency independent Distributes RX from the CDUs to the dTRUs Built up with SW controlled switches. Makes it possible to expand and reconfigure a RBS 2x06 without moving or replacing any RX cables . Only one set of RX cables to cover all configurations Only one type of CXU to cover all configurations with CDU-F,CDU-G Combining and Distribution Unit (CDU) The CDU is the interface between the TRUs and the 2-way antenna system. The task of the CDU is to combine signals to be transmitted from various transceivers and to distribute received signals to the receivers. All signals are filtered before transmission and after reception using band pass filters. A range of CDU type have been developed to support different configurations within the RBS2000 family.They consists of different types of CDUs, including: Without combiners With hybrid combiners With filter combiners to support large configurations

PowerPoint Presentation: 

Different types of CDUs: CDU A CDU C CDU C+ CDU M CDU G Example: CDU C+ can combine 2 CDUs. CDUs with duplex filters make it possible to transmit and receive using the same antenna.

PowerPoint Presentation: 

Transceiver Unit (TRU) One TRU includes all functionality needed for handling one radio carrier ( i.e the 8 time slots in one TDMA frame ).It is responsible for radio transmitting, radio receiving, power amplification and signal processing. The TRU contains a radio frequency test loop between the transmitter and the receiver.This facilitates TRU testing by generating signals and looping them back. TRU’s are connected by a bus to enable frequency hopping.Some RBS products can contain up to 6 TRUs. DTRU -Double TRU Two transceivers in one unit of the same size as the current single TRU. Supporting E-GSM 900 & GSM 1800 Supporting GSM 800 & GSM 1900

PowerPoint Presentation: 

Energy Control Unit (ECU) The ECU controls and supervises the power equipment and regulates the environmental conditions inside the cabinet. The RBS2000 is pre-assembled at the factory including program load and parameter settings making a quick startup possible. Assembly can also be carried out on site.The RBS software is downloaded from the BSC and stored in a non-volatile (flash memory) program store.In a working RBS,this flash memory keeps cell down time low because traffic does not need to be interrupted. Power failure recovery can also be done quickly. Internal Distribution Module (IDM). Actually IDM consists of many MCBs.These MCBs are used to protect all replaceable units from severe sudden voltage fluctuations.

Y-Links: 

Ready for EDGE High throughput (max 13Mb/s) Replaces Timing Bus , Local Bus and X Bus New point-to-point interface between DXU & TRUs Based on LVDS ,( Low Voltage Differential Signalling) interface Backplane connector on DXU with compatibility of 2 1 02/2 2 02 cabinets Each dTRU has two Y links (one for each transciver) Each Y link is divided into two interfaces: Y1: TX control data TX burst data (X Bus data) Y2: Traffic data UL & DL O&M Data Timing Y 7-12 Y 1-6 Y-Links

Distribution Switch Unit, DXU 21: 

The transmission interface: - Supporting four 2 Mbit E1 or 1.5Mbit T1 ports - Total Capacity of up to 8 Mbit/s Abis transmission Removable Flash Card for easy load of BTS SW Support for External Synchronization Bus, ESB Built in indoor EC-functionality (No need for ECU in RBS 2 x 06) HW Prepared to support EDGE modulation on up to 12 TRXs Distribution Switch Unit, DXU 21

Connection Switch Unit, CXU: 

Frequency independent Distributes RX from the CDUs to the dTRUs Built up with SW controlled switches Makes it possible to expand and reconfigure a RBS 2x06 without moving or replacing any RX cables, almost. Only one set of RX cables to cover all configurations Only one type of CXU to cover all configurations with CDU-F, CDU-G Connection Switch Unit, CXU

Double Transceiver Unit, dTRU: 

Two transceivers in one unit of the same size as the current single TRU Two versions, one for GMSK only and one for 8-PSK (EDGE) and GMSK Four versions with frequency bands GSM 800 , E-GSM 900, GSM 1800, or GSM 1900 Built in by-passable hybrid for TX combining together with CDU-G. Supports Software Power Boost HW Prepared to support: - Extended Range (2 slot, 121 km) - Four-branch RX Diversity Double Transceiver Unit, dTRU

Temperature Conditions : 

Condition Minimum Temperature Maximum Temperature Transport -40°C 70°C Storage -25°C 55°C Normal Operation (2206 /2207 ) 5°C 40°C Normal Operation (2106 wo. A/C) -33°C 40°C Normal Operation (2106 w. A/C) -33°C 45°C Temperature Conditions

Radio Site Installation Overview: 

RBS TMR AC power Antenna Tower 600 2200 DF All Units in mm Distance between cable ladder support, max 2m Cable ladder AC Mains Pwr Distribution ROXTEC 600 300 Future Expansion Drip Loop Bending Radius 25mm2 35mm2 50mm2 50mm2 BBS Future Expansion Earth Collection Bar Radio Site Installation Overview

Block diagram for DC Cabinet: 

Block diagram for DC Cabinet Rectifiers DG set PIU (Power Interface Unit) 230V A/C DC Distribution panel Battery Bank BTS Microwave - 24V 230V AC 230V AC +24 V

Block diagram for AC Cabinet: 

Block diagram for AC Cabinet DG set PIU (Power Interface Unit) 230V A/C AC Distribution panel Battery Bank BTS with Inbuilt PSU Microwave 230V AC 230V AC Battery fuse Unit +24V +24V

Dual Band: 

GSM 900: 1x8 GSM 900 GSM 1800: 1x4 GSM 1800 Dual Band

Transceiver Group Synchronization : 

allows to synchronize up to 2 RBSes to work in the same cell 1/1 frequency network 128 trx 64 TGs Transceiver Group Synchronization

RBS 2206 Connection Fields: 

RBS 2206 Connection Fields

Antenna System Test : 

Antenna System Test Standing Wave Ratio SWR D istance To Fault D TF The same test setups for all configurations Different test setup for: Configuration with no TMAs Configuration with dTMA Configuration with ddTMA Configuration with adaptive ant

Anritsu Site Master 331 C: 

Anritsu Site Master 331 C

Example of an approved DTF measurement: 

Example of an approved DTF measurement

Example of an approved SWR measurement: 

Example of an approved SWR measurement

PowerPoint Presentation: 

Basic components of GSM system. GSM system is divided into Two parts. BSS SS BSS Includes your BTS and BSC ,where as SS includes your MSC/VLR,GMSC,HLR. ======================================= BTS Logical Model: BTS Logical Model describes a logical representation of the BTS as viewed from the BSC for the purposes of O&M communication. The model comprises a structured hierarchy of instances of Managed Object (MO) of a given Managed Object Class.

PowerPoint Presentation: 

BTS Logical Model G12 comprises one or more instances of MO of class: Transceiver Group (TG), Central Functions (CF), Transceiver Controller (TRXC), Interface Switch (IS), LAPD Concentrator (CON), Timing Function (TF), Digital Path (DP), Transmitter (TX), Receiver (RX) and Timeslot (TS). BTS Logical Model G01 comprises one or more instances of MO of class: TG, TF, TRXC, TX, RX and TS. Managed Object: The class of all objects within the BTS Logical Model with which the BSC can communicate. A Managed Object (MO) is a logical representation of hardware units and software at the BTS site. Note that hardware can be shared between Managed Objects of different classes. The Transceiver Group is a special case as it does not have any hardware or software of its own. Instead, it consists of a set of Managed Objects from other managed object classes.

General Commands Used for Fault Management : 

General Commands Used for Fault Management 1)To view External Alarm of particular site:- Allip:acl =a1; Allip:acl =a2; Allip:acl =a3; 2) To find out the TG Mo for particular site:- Run RXTCP:MOTY=RXOTG,CELL=<CELL NAME> 3) To check Internal Alarm at site:- Run RXMFP:MO=RXOCF-<TG NO.> It will give printout having codes as :- 2A:8 - VSWR 2A:33 - RX DIVERSITY 2A:41 - LOST COMM. TO TRU 2A:42 - LOST COMM. TO CDU 2B:10 - SITE ON BATTERY 2B:4 - TX SATURATION

PowerPoint Presentation: 

4) To check no. of sites down in Particular BSC:- Run RLCRP:CELL=ALL; Check if BCCH=0,site is down 5) To check the running configuration of a site:- Run RLSLP:CELL=<CELL NAME>; Check for NCH where BCCH,SDCCH & TCH values are displayed. Run RXCDP:MO=RXOTG-<TG No>; Check for the MOs which are in CONFIG & UNUSED,SELECT mode. This command also tells the frequencies alloted TRX wise. 6) To check the state of a cell:- Run RLSTP:CELL=<CELL NAME>; It will shown wheather site is in active or halted state 7) To check the software of BTS:- Run RXMOP:MO=RXOTG-<TG NO>; Check “SWVERACT”

PowerPoint Presentation: 

8) To check the BTS type:- Run RXMFP:MO=RXOCF-<TG. NO>; Check for “RULOGICALID” type ,for 2206,2106,2204 it is mentioned in that parameter. 9) To check the DIP (digital Interface path) status: Run DTSTP:DIP=<DIP NAME>; It will print the status of dip as WO,RDI,LOF,LOS etc 10) To check the devices atttched to the TG:- Run RXAPP:MO=RXOTG-<TG NO>; 11) To check the status of TG,CF,TRX:- RXMSP:MO=RXOTG-<TG NO>; same for CF RXMSP:MO=rxotrx-<tg no>-<tei value>,subord;

When a Site is down:-DO RCA: 

When a Site is down:-DO RCA Find TG no. Check rxmsp if CF is in noop state. Check the status of dip Find dip connected to TG :- RXMDP:MO=RXOCF-<TG NO>;(check device connected to CF) RADEP:DEV=RBLT2-<DEVICE NO>;(check the SNT of device) NTCOP:SNT=ETM2-3;(check the dip name verifying that device in that SNT) DTSTP:DIP=<dip name>; If dip is break escalate to FM engineer. If Dip is working check the external alarm at site If no alarm is there and CF is still in noop state, Try to reload the CF

Create IDB: 

Create IDB

OMT cabinet view: 

OMT cabinet view

Define PCM: 

Define PCM

OMT Event Monitor: 

OMT Event Monitor

OMT Load of SW : 

OMT Load of SW

OMT Load of SW: 

OMT Load of SW

PowerPoint Presentation: 

(4) The High Level Data Link Controller (HDLC) concentrator reads the incoming control channel information and distributes it to the TRUs or DXU accordingly.

Major N/W Failure Reasons:-: 

Major N/W Failure Reasons:- Microwave Hop fading due to bad weather, misalignment of Hop Fibre Cut Power Alarms observed in BSC,MSC. Critical Alarms pending in BSC,MSC.

PowerPoint Presentation: 

Separately installed antenna Compact antennas Integrated power splitter MINI-LINK Modularity

PowerPoint Presentation: 

MINI-LINK Modular design Outdoor Unit Radio Unit (RAU) Compact antenna Indoor unit Modem unit (MMU) Access Module Magazine (AMM)

PowerPoint Presentation: 

MINI-LINK E - Main Components Outdoor module Single coaxial cable Indoor module

PowerPoint Presentation: 

AMM 1U AMM 2U AMM 4U MINI-LINK E Classic i ndoor concept

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Modem Unit - MMU TR1A-TR1D O & M in TP out TR1A-TR1B NCC DC +/- RAU in TP out O & M NCC DC +/- RAU O & M NCC DC +/- RAU O & M NCC DC +/- RAU in TR2A out in TR2A out in TR2B out in TP out TR1A in TR2A out in TP out 2x2 Mbps 2x8 Mbps 4x2/8 Mbps 34+2 Mbps

PowerPoint Presentation: 

MMU (Modem Unit) SMU (Switch Multiplexer Unit) SAU (Service Access Unit) Plug-in Units MINI-LINK E Classic, terminal configurations

PowerPoint Presentation: 

Service Access Unit - SAU O & M O & M EAC EAC EAC EAC USER I/O USER I/O USER I/O DIG SC 5-8 DIG SC 1-4 DIG SC 1-4 BR/EAC1 BR/EAC2 PHONE RAC2 RAC1 RAC1 RAC2 O & M Basic Exp 1 Exp 2

PowerPoint Presentation: 

MINI-LINK Manager Advanced network & element management Maximized network availability Minimized maintenance costs Unrestricted scalability One common microwave management system

PowerPoint Presentation: 

MINI-LINK Ease-of-installation & maintenance Compact, user-friendly mechanical design Simple configuration & fault tracing Plug & play replacement MINI-LINK portfolio easy installation efficient logistics one management system

EXTERNAL ALARMS: 

EXTERNAL ALARMS

PowerPoint Presentation: 

Some basic concepts Alarms :A spontaneous printout describing an alarm situation. Alarm Class :Indicates the priority of an alarm situation.Table1 describes the defined alarm classes ordered by priority from A1(highest) to O2(lowest): Table 1 Alarm Class priority A1 :Fault detected. Action shall be taken immediately, regardless of time of day when the alarm is generated A2 :Fault detected. Action should be taken as soon as possible, but only during normal working hours. A3 :Fault detected. Action should be taken at an appropriate time, preferably within one week.

PowerPoint Presentation: 

O1 :Operator intervention has been made that entails risk for lowered service quality. Shall be acted on as soon as possible during working hours. O2 :Operator intervention has been made that entails temporary change of operational characteristics, but not quality of service. Should be acted on at an appropriate time. ======================================= BTS Logical Model: BTS Logical Model describes a logical representation of the BTS as viewed from the BSC for the purposes of O&M communication. The model comprises a structured hierarchy of instances of Managed Object (MO) of a given Managed Object Class. BTS Logical Model G12 comprises one or more instances of MO of class: Transceiver Group (TG), Central Functions (CF), Transceiver Controller (TRXC), Interface Switch (IS), LAPD Concentrator (CON), Timing Function (TF), Digital Path (DP), Transmitter (TX), Receiver (RX) and Timeslot (TS). BTS Logical Model G01 comprises one or more instances of MO of class: TG, TF, TRXC, TX, RX and TS.

PowerPoint Presentation: 

Managed Object: The class of all objects within the BTS Logical Model with which the BSC can communicate. A Managed Object (MO) is a logical representation of hardware units and software at the BTS site. Note that hardware can be shared between Managed Objects of different classes. The Transceiver Group is a special case as it does not have any hardware or software of its own. Instead, it consists of a set of Managed Objects from other managed object classes.

PowerPoint Presentation: 

What is Power Fail alarm? Mains supply fail is called power fail.In Delhi at many sites 3phase power supply is available and so many sites running on 1phase power supply. What happens when Power Fail occurs in a site? When power fail occurs then site (BTS) at first goes into battery then after a short while DG set on.A BTS (or RBS in Ericsson terminology) is running on +24 volts power supply.Actually here battery placed as battery bank ( i.e combination of many batteries). Battery bank voltage is about 23.5volts.Generally there are two battery banks are placed in the shelter.Total battery bank capacity is 800amph ( each have a capacity of 400amph).Depends on the condition of batteries this combined battery can serve supply to BTS for maximum 4hours. How a site can get its power and what are the power related faults? The detailed procedure is given below: The mains power supply at first enters into the PSU (Power Supply Unit).The RBS2000 series is based on standardized hardware units called Replaceable Unit (RU). The major RU are: (1) Power Supply Unit (PSU) or Power Interface Unit (PIU), (2) Combining and Distribution Unit (CDU),

PowerPoint Presentation: 

(3) Transceiver Unit (TRU), (4) Distribution Switch Unit (DXU), (5) Energy Control Unit (ECU). Power Supply Unit or Power Interface Unit: The PSU or PIU rectifies the power supply voltage to the +24VDC necessary for RBS operation. Function of PIU: Whenever mains power supply goes down it starts DG set and after power supply restore stop DG set. To regulate mains input voltage. Regulate means stability. According to the diagram given below 3phase mains power supply (440 volts) enters into the PIU cabinet through line1 and line2 (L1&L2).Then it goes to LCU (Line Conditioner Unit).LCU is an unit which steps down 440volt A.C. mains supply to 220Volts A.C.After stepping down it goes through a auto changeover circuit and then enters into the SMPS.If mains supply is available SMPS charges the batteries as well as provides supply to BTS.SMPS consists of several rectifier modules.When mains power

PowerPoint Presentation: 

supply goes down the rectifier fail occur.At that condition we can see that some red LEDs are blinking inside the rectifier module.We can observe rectifier fail for maximum two hours.After that it it exists then certainly rectifier module is faulty.Then we replace

PowerPoint Presentation: 

that particular rectifier module.Some MCBs (Mauled Case Circuit Breaker) associated with these rectifier modules.Function of these MCBs is to protect overloading or short circuit.If over current is flowing or short circuit occur or rectifier module turn to be really faulty MCB will trip.For a MCB trip event site may go down. Inside the SMPS there is a relay.This relay is working on electromagnetic induction principle.It has two contacts inside .One is normally open contact and other is normally closed contact.Whenever mains power supply goes down the normally open contact get closed and its another end connects the battery bank.At that time normally closed contact get opened.After mains restore the connection get reversed.Some fuses exist between SMPS and battery bank.They are called battery fuse.They are looking like pressure switch.They protect BTS from sudden hazards.Battery fuse fail occur: (1)when over current flow or short circuit happen, (2) when battery charge severely drained, below 22.5v D.C.If battery fuse fail occur the site will go down. Now after mains power supply goes down site at first goes into battery and after a short while(within 1minute) auto change-over circuit connects it to DG set.Where DG saver Card exists in PIU Auto change-over circuit connects dg at battery voltage minimum 21volt or room temperature above 30 0 C.Then from DG set site gets its power supply through SMPS.Now we will discuss about DG.

PowerPoint Presentation: 

DG means Digital Generator.It generates power for a BTS.It has two main parts: (1) engine, (2) Alternator.Engine rotates shaft and alternator generates current.Frequency is directly proportional to the R.P.M (revolution per minute).Voltage is directly proportional to the excitation.1500 rpm rotational speed can generate 230v a.c.Capacity of a DG is about 15KVA (KVA-Killo Volt Ampere). That means power developed=15KVA*0.8=12K.W (Killo Watt).One 15KVA DG is maintaining 8liter lubricating oil.This lubricating oil minimizes friction of shaft.This lubricating must have some pressure.DG maintains normally 2.5kg/cm 2 to 6kg/cm 2 oil pressure . Unit of oil pressure: 1kg/cm 2 =16 lb/inch 2 . When oil pressure goes down below 2.5kg/cm 2 then LLOP (Low Lubricating Oil Pressure) on alarm will generate.There is a oil pressure safety switch in DG.It has a connection with PIU.PIU has a connection with DDF (Digital Distribution Frame). DDF assembles all Power related alarms and send it to network through BTS.From the another end we can view these alarms.We can observe oil level with the help of a stick like measuring instrument.In the body of this stick there have some marks which indicates oil level.Generally it dipped into the lubricating oil.When we get it out from its position then we can observe the present oil level with help of those marks.In DG there also present Oil pressure

PowerPoint Presentation: 

indicating dial by which we can determine what is present oil pressure.A DG generally is running on diesel.DG also contains some battery. Whenever mains power supply goes down this battery starts the DG set. DG fail to start:DG fail to start occurs when : (1) DG fuel low (Diesel), (2) DG Battery faulty, (3) Automation of PIU faulty, (4) Internal fault of Engine side (Mechanical). Summery: The 440volt A.C. mains power supply run a site in normal condition.This 440volt AC at first step down to 220v AC in LCU.Then it again step downed to +/- 24volt and rectified in SMPS.SMPS output provides BTS +24volt DC. When mains power supply is not available then site at first goes into battery. After draining (about 21v) of some battery voltage automatic change-over circuit of PIU connects the site with DG. Then DG generate 220volt A.C. and give it to the BTS after stepping down and rectified to +24volt DC through SMPS. How a site maintains its temperature? A site normally maintains 34.5 0 C temperature.It is maintained with the help of Air Conditioner (A.C.).As the temperature crosses 35 0 C temperature alarm generate.If this

PowerPoint Presentation: 

temperature turns about 50 0 C then site will go down.Because when temperature of the shelter drastically increase, the internal temperature of BTS will tremendously increase. Malfunctioning of the system then will start.DXU will stop its functionality.BTS will go down. What is TMA and what its functionality? TMA means Transceiver Mounted Amplifier.This is one type of amplifier which is placed at the top of antenna. This amplifier will increase normal transmitter power (43dbm) about 2/3dbm.TMA is generally used in highway sites to transmit more power for large range. When some fault occurs in TMA then this alarm at first comes into DDF and then into BTS. After that it goes through the network and reaches to our terminal.

PowerPoint Presentation: 

What is the meaning of DG in Manual mode? In PIU there are two junctions one for mains connections and other for DG I/P.In DG I/P junction there is a switch which have two modes (1) Auto,(2)Manual.Normally DG runs on Auto mode. If there is any problem in PIU then we switch over it in manual mode. Note : There are two types of sites (1) Sites with PIU,(2)Sites with AMPS power panel (Non PIU site). In a non PIU site there exists AMPS power panel. In this case there is no PIU.In place of PIU AMPS power panel placed. AMPS power panel consists of Servo Stabilizer. 220v a.c.power supply go to the Servo Stabilizer.Servo stabilizer regulate voltage.That means if mains power supply is more or less than 220volt A.C.then it decrease or increase its value and then the line go to the AMF circuit (Auto Mains

PowerPoint Presentation: 

Failure Circuit ).AMF is like a auto change-over circuit of PIU.Whenever mains power supply goes down it starts DG.One line from the AMF go the DG and the other go to the SMPS.