INDUSTRIAL TRAINING

PROJECT REPORT

AT

ACKNOWLEDGEMENT

I express my deep gratitude to Ms. Rama Gupta

,Jt.G.M.(Comm.),Airports Authority of India Jaipur

Airport for providing me this golden opportunity to

attend the Industrial/Vocational training.

My sincere thanks to Sh.Kamlesh Kumar,

Manager (Elex), our training co-ordinator for

providing the proper guidance and continuous

encouragement for making this training successful .

I am also thankful to all the CNS faculty

members for their keen interest and at last my

coordinal thanks to my batch mates and friends for

their cooperation.

Dated : / / 2013

TABLE OF CONTENTS

Name Page No.

1. Brief Description of Jaipur 03

2. General Information 05

3. Brief Description of CNS Department 06

4. Classification of CNS Facilities 08

5. Basic Communication system 13

6. VCCS/Tape recorder/DATIS 18

7. Frequency bands uses in comm.. 20

8. AFTN/AMSS 21

9. Nav-aids DVOR/DME 28

10. Instrument Landing System (ILS) 32

11 .Security Equipments 42

12. Automation system 45

13. ADS-B 49

14.Intranet/LAN/WAN 56

15.Figures

Brief Description of JAIPUR

Jaipur is the Capital city of Rajasthan and is also called the PINK CITY.

(Zero mile point). It is well connected with other major cities by Rail/Road

and air.

Area: 3, 42,237Sq Km

Population: 2.6 Million as per 2001 census

Tourist Places: -

(i) Amber Palace: 20 Km from Airport, in Red sandstone with

marble interiors famous for fascinating blend of Rajput and

Mughal architecture.

(ii) Hawa Mahal: Palace of wind with latticed Jharokhas 14 Km

away from Airport. Heart of city, is a fusion of Rajputana and

Mughal Acrtitecture

(iii) City Place: Fabulous museum displays possessions of the

Jaipur Royal family.

(iv) Jantar Mantar: An Unique open air observatory built by the

founder of Jaipur- Sawai Jai singh. It is complex instruments

used for measuring local time ,the altitude of stars, meridian etc.

(v) Jai Garh :The victory forts-world’s largest cannon Jaivan.

Perched atop the hill Jaigarh.

Distance from Railway Station: 12 Km

Jaipur Runway strip 15/33 with one terminal office and two Hanger was

constructed by Maharaja Mansingh II in 1932 named as Sanganer

Airport. Dakota Aircraft was used for domestic and International flight

from Jaipur to Karachi/Lahore. New Runway with orientation 09/27 of

length 9000 feet has been constructed and de-used Runway 15/33 is

being used for parking the Aircrafts. The salient features of the New

Terminal Building (Terminal-2) are: -

Glass and steel structure with passenger friendly facilities such as:

(a) Most modern security system

(b) Centrally air-conditioning system. Passenger Boarding Bridge

(Aerobridges),

(c) Two glass aerobridges with visual docking system.

(d) On Line Baggage conveyer system.

(e) Escalator and Glass Lifts.

(f) Large Duty Free Shoe Area.

(g) Twin-Level connection segregating arrival and Departure area.

(h) Underground pedestrian link to/from car parking area to

Concourse.

(i) Peak Pax-500 (250 Departure, 250 Arrival)

The Airlines operating at this airport are: -

(a) International: Indian , Air Arabia, & Air India Express

(b) Domestic: Indian, Jet Airways, Jet lite, Indigo, Kingfisher, Go Air,

Spice Jet.

All domestic flights are to be operated from new terminal building (T-2)

and all International flights are to be operated from the existing old

terminal building (T-1).

Technical Data of the Airport:

a) Aerodrome Reference Code: 4D

b) Elevation: 1263.10 Feet (385 meter)

c) ARP coordinates: 26°49′26.3″N 075°48′′12.5″E

d) Main RWY orientation: 27/09

e) RWY dimension: 2797.05m X 45m

f) Apron dimension 230 m X 196 m

g) Parking Bays

GENERAL INFORMATION

1. Name of Airport : Jaipur Airport, Jaipur

2. Type of Airport : Civil Aerodrome

3. Address : OIC, AAI, Jaipur Airport

Jaipur - 302029

4. Operational Hours : 24 hours

5. Name & Designation of : Rama Gupta

Officer-in-Charge Jt.GM (Com)

6. Region : Northern Region

7. RHQ : New Delhi

8. Nature of Station : Non Tenure

JAIPUR AIRPORT – VIJP IST=(UTC + 0530)

Geographical Coordinates (WGS–84) : 26º 49' 26.3” N

75º 48' 12.5” E

Aerodrome Reference Code : 4 D

Aerodrome Reference Point (ARP) Elevation : 384.96 M

BRIEF DESCRIPTION / ROLE OF CNS DEPARTMENT 1.To provide uninterrupted services of Communication, Navigation

and Surveillance (CNS) facilities for the smooth and safe movement of

aircraft (over flying, departing & landing) in accordance with ICAO

standards and recommended practices.

2. To maintain Security Equipments namely X-Ray Baggage systems

(XBIS), Hand Held Metal Detectors (HHMD) and Door Frame Metal

Detectors (DFMD).

3. To provide and maintain inter-unit communication facility i.e.

Electronic Private Automatic Exchange Board (EPABX)

4. To maintain the Computer systems including peripherals like

printers, UPS etc. provided in various sections connected as

standalone as well as on Local Area Network (LAN).

5. To maintain the passenger facilitation systems like Public Address

(PA) system, Car Hailing System and Flight Information Display

System (FIDS).

6. To maintain and operate Automatic Message Switching system

(AMSS) used for exchange of messages over Aeronautical Fixed

Telecommunication Network (AFTN).

7. To provide Communication Briefing to pilots by compiling NOTAM

received from other International NOF.

8. To maintain and operate Fax machine.

9. To co-ordinate with telephone service providers for provision and

smooth functioning of auto telephones/ hotlines/ data circuits.

Classification of CNS facilities Name of the Equipment Make QTY FREQ POWER

COMMUNICATION EQUIPMNET

VHF AM Sets

Transmitters

OTE

DT-100

PARKAIR

125.25

126.6

50W

Receivers

OTE

DR-100

PARKAIR

125.25

126.6

VHF AM Transreceivers PAE 5610

PAE BT6M

125.25

DS-Radio

JORTON

I-COM

125.25

125.25

125.25

DVR RETIA

64

Chnl NA

64 kbps line

NA NA

FIDS

IDDS

SOLARI NA NA

Digital Clock

Bihar

Commn. NA NA

DSCN VIASAT

LAN/WAN Cisco Tele NA NA

EPABX

Coral

Panasonic

NA

NA

NA

NA

VCCS SCHMID NA NA

Mobile Radio (FM)

Communication

(BASE STATION)

MOTORO

LA

161.825

Mhz

For

CISF

166.525

Mhz

For

AAI

--

10W

--

VERTEX

Standard

Mobile Radio (FM)

Communication

(Hand Held Sets)

MOTORO

LA

SIMCO)

Vertex

Standard

KENWOO

D

161.825

Mhz

166.525

Mhz

--

--

--

AUTOMATION INDRA NA NA TYPE B1

ADS-B COMSOFT 1090

Mhz

NA

NAVIGATION EQUIPMENT

DVOR (JJP)

THALES

420

112.9

Mhz. 100W

HP DME(JJP)

(Collocated with D-VOR)

THALES

Airsys-435

1100

1163

Mhz

1 KW

LOCALIZER (IJIP)

NORMAC-

7013

109.9

Mhz 15W

GLIDE PATH

NORMAC-

7033

333.8

Mhz 5W

LP DME (IJIP Collocated

with GP)

THALES

Airsys -415

997

1060

Mhz

100W

Locator Outer SAC 100 295 Khz 50W

SECURITY EQUIPMENTS

X-BIS SYSTEM

Departure Lounge 100100V

Heimann (Ger)

Security Hold Area

6040i Heimann (Ger)

Departure Lounge 100100V

Heimann (Ger)

Security Hold Area

6040i Heimann (Ger)

Explosive Trace

Detectors

Smith 500 DT

Smith

IONSCAN500DT

(Singapore)

DFMD

METOR-200

CEIA

CCTV INFINOVA

PA SYSTEM

BOSCH

BASIC COMMUNICATION SYSTEM

1.1 Introduction: Transmitter, Receiver & Channel

Introduction

Communication is the process of sending, receiving and processing of

information by electrical means. It started with wire telegraphy in 1840

followed by wire telephony and subsequently by radio/wireless

communication. The introduction of satellites and fiber optics has made

communication more widespread and effective with an increasing

emphasis on computer based digital data communication. In Radio

communication, for transmission information/message are first converted

into electrical signals then modulated with a carrier signal of high

frequency, amplified up to a required level, converted into

electromagnetic waves and radiated in the space, with the help of

antenna. For reception these electromagnetic waves received by the

antenna, converted into electrical signals, amplified, detected and

reproduced in the original form of information/message with the help of

speaker.

Transmitter

Unless the message arriving from the information source is electrical in

nature, it will be unsuitable for immediate transmission. Even then, a lot

of work must be done to make such a message suitable. This may be

demonstrated in single-sideband modulation, where it is necessary to

convert the incoming sound signals into electrical variations, to restrict

the range of the audio frequencies and then to compress their amplitude

range. All this is done before any modulation. In wire telephony no

processing may be required, but in long-distance communications,

transmitter is required to process, and possibly encode, the incoming

information so as to make it suitable for transmission and subsequent

reception.

Eventually, in a transmitter, the information modulates the carrier, i.e., is

superimposed on a high-frequency sine wave. The actual method of

modulation varies from one system to another. Modulation may be high

level or low level, (in VHF we use low level modulation) and the system

itself may be amplitude modulation, frequency modulation, pulse

modulation or any variation or combination of these, depending on the

requirements. Figure 1.1 shows a low-level amplitude-modulated

transmitter type.

Antenna

AUDIO IN

Channel

The acoustic channel (i.e., shouting!) is not used for long-distance

communications and neither was the visual channel until the advent of

the laser. "Communications," in this context, will be restricted to radio,

wire and fiber optic channels. Also, it should be noted that the term

channel is often used to refer to the frequency range allocated to a

CRYSTAL

OSC & AMP

MODULATOR

& DRIVER PA

RF OUTPUT

POWER AMP

AUDIO

AMPLIFIER

Figure 1.1 Block diagram of typical radio transmitter

particular service or transmission, such as a television channel (the

allowable carrier bandwidth with modulation).

It is inevitable that the signal will deteriorate during the process of

transmission and reception as a result of some distortion in the system,

or because of the introduction of noise, which is unwanted energy,

usually of random character, present in a transmission system, due to a

variety of causes. Since noise will be received together with the signal,

it places a limitation on the transmission system as a whole. When

noise is severe, it may mask a given signal so much that the signal

becomes unintelligible and therefore useless. Noise may interfere with

signal at any point in a communications system, but it will have its

greatest effect when the signal is weakest. This means that noise in the

channel or at the input to the receiver is the most noticeable.

Receiver

There are a great variety of receivers in communications systems,

since the exact form of a particular receiver is influenced by a great

many requirements. Among the more important requirements are the

modulation system used, the operating frequency and its range and the

type of display required, which in turn depends on the destination of the

intelligence received. Most receivers do conform broadly to the super

heterodyne type, as does the simple receiver whose block diagram is

shown in Figure 1.2.

Antenna

Speaker

Mixer

Figure 1.2 Block diagram of AM super heterodyne receiver

RF Stage

Intermediate

Frequency

Amplifier

Demodulator

Audio Voltage

and Power

amplifiers

Local

Oscillator

Receivers run the whole range of complexity from a very simple crystal re-

ceiver, with headphones, to a far more complex radar receiver, with its

involved antenna arrangements and visual display system, which will be

expanded upon in Chapter 6. Whatever the receiver, it’s most important

function is demodulation (and sometimes also decoding). Both these processes

are the reverse of the corresponding transmitter modulation processes.

As stated initially, the purpose of a receiver and the form of its output

influence its construction as much as the type of modulation system

used. The output of a receiver may be fed to a loudspeaker, video

display unit, teletypewriter, various radar displays, television picture

tube, pen recorder or computer: In each instance different arrangements

must be made, each affecting the receiver design. Note that the

transmitter and receiver must be in agreement with the modulation and

coding methods used (and also timing or synchronization in some

systems).

Transmitter (or equipment) modulation.

Transmitter modulation is one in which, the carrier and total sideband

components are combined in a fixed phase relationship in the equipment

(say transmitter) and the combined wave follow a common RF path from

the transmitting antenna through space to the receiver ensuring no

introduction of phase difference between the carrier and the TSB on its

way. It is obvious that the mixing (multiplication) of the carrier and the

modulating signal has to be taken place to produce the TSB within the

equipment only, before combining (adding) it with carrier within or

outside the equipment.

Space Modulation

Another type of amplitude modulation process may be required to be

used in many places like Navaids where the combination (addition) of

sideband only (SBO comprising one or more TSB(s)) and the carrier with

or without the transmitter modulated sidebands takes place in space.

Note that both of the SBO or carrier with sidebands (CSB) are

transmitter modulated but when all the required signals out of these

three namely SBO, CSB or carrier are not radiated from the same

antenna the complete modulation process will be realized rather the

composite modulated waveform will be formed at the receiving point by

the process of addition of all the carriers and all the sidebands (TSBs).

The process of achieving the complete modulation process by the

process of addition of carriers and sidebands (TSBs) at the receiving

point in space is called the “Space Modulation” which means only that

modulation process is achieved or completed in space rather than in

equipment itself but not at all that space is modulated.

VOICE COMMUNICATION CONTROL SYSTEM

INTRODUCTION AND NEED OF VCCS AT AIRPORTS

The Voice Communication Control System (VCCS) is a Voice Switch and Control System for networking an airport VHF

communication system. It is an electronic switching system, which controls the complex flow of speech data between air

traffic controllers on ground and aircraft. The system has been designed using Complementary Metal Oxide Semiconductor

(CMOS) digital circuits and is very easy to operate.

The VCCS is based on a modular architecture. The heart of the system is a Central Switching Unit (CSU) in which the data

inputs from various controller workstations are separately processed. The controller workstation installed at the ATS units

works as a command centre from which the air traffic controller operates the VHF RT. Each Controller Workstation is assisted

by a Radio Telephony Display Console, Audio Interface and Headset Interface Units. A multibus data link connects the CSU

with each controller workstation.

INTRODUCTION TO TAPE RECORDING

PURPOSE OF TAPE RECORDER

The purpose of tape recorder is to store the Sound by recording

of sound either by Disc Recording, Film Recording or Magnetic

Recording. In our Department, we are using Magnetic

Recording to record the communications/speech between Air

(Aircraft) to Ground, Ground to Ground, telephones, Intercom’s

etc. For any miss happening or any other reason, the

conversations of past period can be checked to find out the root

cause so that in future such types of mistakes can be avoided.

DIGITAL AIRPORT TERMINAL INFORMATION SYSTEM (DATIS)

Introduction

Digital Airport Terminal Information System (DATIS) is an

intelligent announcing system used for Automatic Terminal

Information Service (ATIS) – for the automatic provision of

current, routine information (weather, runway used etc.) to

arriving and departing aircraft throughout 24 hrs or a specific

portion thereof. The System is Completely solid-state,

without any moving parts. The design is based around

advanced digital techniques viz., PCM digitization, high

density Dynamic RAM Storage and microprocessor control.

This ensures reproduction of recorded speech with high

quality and reliability. Storage capacity normally supplied is

for 4 minutes Announcement, and as the system design is

modular, it can be increased by simply adding extra memory.

The system is configured with fully duplicated modules,

automatic switch-over mechanism and Uninterrupted Power

Supply to ensure Continuous System availability.

Frequency band and its uses in communications

Table 1.1 Radio Waves ClassificatioN

Band Name Frequency Band

Ultra Low Frequency (ULF) 3Hz - 30 Hz

Very Low Frequency (VLF) 3 kHz - 30 kHz

Low Frequency (LF) 30 kHz - 300 kHz

Medium Frequency (MF) 300 kHz - 3 MHz

High Frequency (HF) 3 MHz - 30 MHz

Very High Frequency (VHF) 30 MHz - 300 MHz

Ultra High Frequency (UHF) 300 MHz -3 GHz

Super High Frequency (SHF) 3 GHz - 30 GHz

Extra High Frequency (EHF) 30 GHz - 300 GHz

Infrared Frequency 3 THz- 30 THz

Frequencies band uses in communication

NAME OF

THE

EQUIPMENT

FREQUENCY

BAND

USES

NDB 200 – 450 KHz Locator, Homing & En-route

HF 3 – 30 MHz Ground to Ground/Air Com.

Localizer 108 – 112 MHz Instrument Landing System

VOR 108 – 117.975 MHz Terminal, Homing & En-route

VHF 117.975 – 137 MHz Ground to Air Comm.

Glide Path 328 – 336 MHz Instrument Landing System

DME 960 – 1215 MHz Measurement of Distance

UHF LINK 0.3 – 2.7 GHz Remote Control, Monitoring

RADAR 0.3 – 12 GHz Surveillance

AFTN SWITCHING SYSTEM & COMMUNICATION

INTRODUCTION

In AFTN, information is exchanged between many stations. The

simplest form of communication is point-to-point type, where

information is transmitted from a source to sink through a medium.

The source is where information is generated and includes all

functions necessary to translate the information into an agreed

code, format and procedure. The medium could be a pair of wires,

radio systems etc. is responsible for transferring the information.

The sink is defined as the recipient of information; it includes all

necessary elements to decode the signals back into information.

CLASSIFICATION OF AFTN SWITCHING SYSTEM

A switching system is an easy solution that can allow on demand

basis the connection of any combination of source and sink

stations. AFTN switching system can be classified into 3 (three)

major categories:

1. Line Switching

2. Message Switching

3. Packet Switching.

LINE SWITCHING

When the switching system is used for switching lines or circuits it

is called line-switching system. Telex switches and telephones

exchanges are common examples of the line switching system.

They provide user on demand basis end-to-end connection. As

long as connection is up the user has exclusive use of the total

bandwidth of the communication channel as per requirement. It is

Interactive and Versatile.

MESSAGE SWITCHING

In the Message Switching system, messages from the source are

collected and stored in the input queue which are analysed by the

computer system and transfer the messages to an appropriate

output queue in the order of priority.

The message switching system works on store and forward

principle. It provides good line utilization, multi-addressing,

message and system accounting, protects against blocking

condition, and compatibility to various line interfaces.

PACKET SWITCHING SYSTEM

This system divides a message into small chunks called packet.

These packets are made of a bit stream, each containing

communication control bits and data bits. The communication

control bits are used for the link and network control procedure and

data bits are for the user.

A packet could be compared to an envelope into which data are

placed. The envelope contains the destination address and other

control information. Long messages are being cut into small

chunks and transmitted as packets. At the destination the network

device stores, reassembles the incoming packets and decodes the

signals back into information by designated protocol. It can handle

high-density traffic. Messages are protected until delivered. No

direct connection required between source and sink. Single port

handles multiple circuits access simultaneously and can

communicate with high speed.

AERONAUTICAL TELECOMMUNICATION NETWORK

(ATN)

The basic objective of CNS/ATM is ‘Accommodation of the users preferred

flight trajectories’. This requires the introduction of automation and adequate

CNS tools to provide ATS with continuous information on aircraft position and

intent . In the new CNS/ATM system, communications with aircraft for both

voice and data (except for polar region) will be by direct aircraft to satellite

link and then to air traffic control (ATC) centre via a satellite ground earth

station and ground-ground communication network . voice communication

(HF) will be maintained during the transition period and over polar region until

such time satellite communication is available. In terminal areas and in some

high density airspaces VHF and SSR mode S will be used.

The introduction of data communication enables fast exchange of

information between all parties connected to a single network. The

increasing use of data communications between aircraft and the various

ground systems require a communication system that gives users close

control over the routing of data, and enables different computer systems

to communicate with each other without human intervention.

In computer data networking terminology, the infrastructure required to

support the interconnection of automated systems is referred to as an

Internet. Simply stated, an Internet comprises the interconnection of

computers through sub-networks, using gateways or routers. The inter-

networking infrastructure for this global network is the Aeronautical

Telecommunication Network (ATN).

The collection of interconnected aeronautical end-system(ES),

intermediate-system(IS) and sub-network (SN) elements administered

by International Authorities of aeronautical data-communication is

denoted the Aeronautical Telecommunication Network (ATN).

The ATN will provide for the interchange of digital between a wide

variety of end-system applications supporting end-users such as Aircraft

operation, Air traffic controllers and Aeronautical information specialists.

The ATN based on the International organization for standardization

(ISO). Open system interconnection (OSI) reference model allows for the

inter- operation of dissimilar Air-Ground and ground to ground sub-

networks as a single internet environment.

End-system attached to ATN Sub-network and communicates with End

system with other sub-networks by using ATN Routes. ATN Routes can

be either mobile (Aircraft based) or fixed (Ground based).

The router selects the logical path across a set of ATN sub-networks that

can exists between any two end systems. This path selection process

uses the network level addressing quality of service and security

parameters provided by the initiating en system. Thus the initiating end

system does not need to know the particular topology or availability of

specific sub-networks. The ATN architecture is shown in the figure.

Present day Aeronautical communication is supported by a number of

organizations using various net working technologies. The most eminent

need is the capability to communicate across heterogeneous sub-

networks both internal and external to administrative boundaries. The

ATN can use private and public sub-net works spanning organizational

and International boundaries to support aeronautical applications. The

ATN will support a data transport service between end-users which is

independent of the protocols and the addressing scheme internal to any

one participating sub-networks. Data transfer through an Aeronautical

internet will be supported by three types of data communication sub-

networks.

a. The ground network – AFTN,ADNS,SITA Network

b. The Air-ground network – Satellite, Gate-link, HF, VHF, SSR

Modes

c. The Airborne network – the Airborne Data Bus, Communication

management unit.

THE GROUND NETWORK

It is formed by the Aeronautical Fixed telecommunication network

(AFTN), common ICAO data interchange network (CIDIN) and Airline

industry private networks

THE AIR-GROUND NETWORK

The Air-Ground sub networks of VHF, Satellite, Mode S, gate link, (and possibly

HF) will provide linkage between Aircraft-based and ground-based routers

(intermediate system).

THE AIRBORNE NETWORK

It consists of Communication Management Unit (CMU) and the Aeronautical

radio incorporation data buses (ARINC). Interconnectivity to and inter

operability with the Public data Network (PDN) will be achieved using gate-

ways to route information outside the Aeronautical environment.

ADNS (AIRNC DATA NETWORK SERVICE)

The backbone of the ARINC communication services s the ARINC Data Network

Service. The network provides a communication interface between airlines,

AFTN, Air-route Traffic Control Centres ( ARTCC) and weather services. ADNS is

also used to transport air ground data link messages and aircraft

communication addressing and reporting system (ACARS).

SITA NETWORK

SITA’s worldwide telecommunication network is composed of switching

centers interconnected by medium to high speed lines including international

circuits. The consolidated transmission capacity exceeds 20 Mbps and the

switching capacity exceeds 150 million data transactions and messages daily.

THE AIR_GROUND COMMUNICATION SYSTEM

The available/planned air-ground communication systems are-

a. Satellite

b. Gate link

c. HF radio

d. SSR Mode S

e. VHF

NAVIGATIONAL AIDS

VHF Omni Range (V.O.R)

VOR, short for VHF Omni-directional Range, is a type of radio

navigation system for aircraft. VORs broadcast a VHF radio signal

encoding both the identity of the station and the angle to it, telling

the pilot in what direction he lies from the VOR station, referred to

as the radial. Comparing two such measures on a chart allows for

a fix. In many cases the VOR stations also provide distance

measurement allowing for a one-station fix.

It operates in the VHF band of 112-118 MHz, used as a medium to

short range Radio Navigational aid. It works on the principle of

phase comparison of two 30 Hz signals i.e. an aircraft provided

with appropriate Rx, can obtain its radial position from the range

station by comparing the phases of the two 30 Hz sinusoidal

signals obtained from the V.O.R radiation. Any fixed phase

difference defines a Radial/Track (an outward vector from the

ground station into space). V.O.R. provides an infinite number of

radials/Tracks to the aircrafts against the four provided by a LF/MF

radio range.

PURPOSES AND USE OF VOR:

1. The main purpose of the VOR is to provide the navigational signals for an aircraft receiver, which will allow the pilot to determine the bearing of the aircraft to a VOR facility.

2. In addition to this, VOR enables the Air Traffic Controllers in the Area Control Radar (ARSR) and ASR for identifying the aircraft in their scopes easily. They can monitor whether aircraft are following the radials correctly or not.

3. VOR located outside the airfield on the extended Centre line of the runway would be useful for the aircraft for making a straight VOR approach. With the help of the AUTO PILOT aircraft can be guided to approach the airport for landing.

4. VOR located enroute would be useful for air traffic 'to maintain their PDRS (PRE DETERMINED ROUTES) and are also used as reporting points.

5. VORs located at radial distance of about 40 miles in different directions around an International Airport can be used as holding VORs for regulating the aircraft for their landing in quickest time. They would be of immense help to the aircraft for holding overhead and also to the ATCO for handling the traffic conveniently.

DISTANCE MEASURING EQUIPMENT(DME)

As early as 1946 many organisations in the West took an active

part in the development of DME system. The Combined Research

Group (CRG) at the Naval Research Laboratory (NRL) designed

the first experimental L band DME in 1946.

The L band, between 960 MHz and 1215 MHz was chosen for

DME operation mainly because:

a. Nearly all other lower frequency bands were occupied.

b. Better frequency stability compared to the next higher

frequencies in the Microwave band.

c. Less reflection and attenuation than that experienced in the

higher

Frequencies in the microwave band.

d. More uniform omni directional radiation pattern for a given

antenna height than that possible at higher frequencies in the

microwave band.

PURPOSES AND USE OF DME

PURPOSE OF DME INSTALLATION

Distance Measuring Equipment is a vital navigational Aid, which

provides a pilot with visual information regarding his position

(distance) relative to the ground based DME station. The facility

even though possible to locate independently, normally it is

collocated with either VOR or ILS. The DME can be used with

terminal VOR and holding VOR also. DME can be used with the

ILS in an Airport; normally it is collocated with the Glide path

component of ILS.

Association of DME with VOR

Associated VOR and DME facilities shall be co-located in

accordance with the following:

a. Coaxial co-location: the VOR and DME antennas are located

on the same vertical axis; or

b. Offset co-location:

For those facilities used in terminal areas for approach purposes or other procedures where the highest position fixing accuracy of system capability is required, the separation of the VOR and DME antennas does not exceed 30 m (100 ft) except that, at Doppler VOR facilities, where DME service is provided by a separate facility, the antennas may be separated by more than 30 m (100 ft), but not in excess of 80 m (260 ft);

For purposes other than those indicated above, the separation of the VOR and DME antennas does not exceed 600 m (2,000 ft).

Association of DME with ILS

Associated ILS and DME facilities shall be co-located in

accordance with the following:

a. When DME is used as an alternative to ILS marker beacons, the DME should be located on the airport so that the zero range indication will be a point near the runway.

b. In order to reduce the triangulation error, the DME should be sited

to ensure a small angle (less than 20 degrees) between the approach

path and the direction to the DME at the points where the distance

information is required.

c. The use of DME as an alternative to the middle marker

beacon assumes a DME system accuracy of 0.37 km (0.2

NM) or better and a resolution of the airborne indication such

as to allow this accuracy to be attained.

The main purposes of DME installations are summarised as

follows:

For operational reasons

As a complement to a VOR to provide more precise navigation service in localities where there is:

o High air traffic density

o Proximity of routes

As an alternative to marker beacons with an ILS. When DME is used as an alternative to ILS marker beacons, the DME should be located on the Airport so that the zero range indication will be a point near the runway.

As a component of the MLS

The important applications of DME are:

Provide continuous navigation fix (in conjunction with VOR);

Permit the use of multiple routes on common system of airways to resolve traffic;

Permit distance separation instead of time separation between aircraft occupying the same altitude facilitating reduced separation thereby increasing the aircraft handling capacity;

Expedite the radar identification of aircraft; and

INSTRUMENT LANDING SYSTEM

Purpose and use of ILS:

The Instrument Landing System (ILS) provides a means for safe landing of

aircraft at airports under conditions of low ceilings and limited visibility.

The use of the system materially reduces interruptions of service at

airports resulting from bad weather by allowing operations to continue at

lower weather minimums. The ILS also increases the traffic handling

capacity of the airport under all weather conditions.

The function of an ILS is to provide the PILOT or AUTOPILOT of a landing

aircraft with the guidance to and along the surface of the runway. This

guidance must be of very high integrity to ensure that each landing has a very

high probability of success.

COMPONENTS OF ILS:

The basic philosophy of ILS is that ground installations, located in the

vicinity of the runway, transmit coded signals in such a manner that pilot is

given information indicating position of the aircraft with respect to correct

approach path.

To provide correct approach path information to the pilot, three different

signals are required to be transmitted. The first signal gives the

information to the pilot indicating the aircraft's position relative to the

center line of the runway. The second signal gives the information

indicating the aircraft's position relative to the required angle of descent,

where as the third signal provides distance information from some

specified point.

These three parameters which are essential for a safe landing are Azimuth

Approach Guidance, Elevation Approach Guidance and Range from the

touch down point. These are provided to the pilot by the three

components of the ILS namely Localizer, Glide Path and Marker Beacons

respectively. At some airports, the Marker Beacons are replaced by a

Distance Measuring Equipment (DME).

This information is summarized in the following table.

ILS Parameter ILS Component

a. Azimuth Approach Guidance Provided by Localizer

b. Elevation Approach

Guidance

Provided by Glide Path

c. Fixed Distances from

Threshold

Provided by Marker Beacons

d. Range from touch down

point

Provided by DME

Localizer unit:

The localizer unit consists of an equipment building, the transmitter

equipment, a platform, the antennas, and field detectors. The antennas

will be located about 1,000 feet from the stop end of the runway and

the building about 300 feet to the side. The detectors are mounted on

posts a short distance from the antennas.

Glide Path Unit :

The Glide Path unit is made up of a building, the transmitter equipment,

the radiating antennas and monitor antennas mounted on towers. The

antennas and the building are located about 300 feet to one side of the

runway center line at a distance of approximately 1,000 feet from the

approach end of the runway.

Figure 2. shows the typical locations of ILS components

Marker Units :

Three Marker Units are provided. Each marker unit consists of a

building, transmitter and directional antenna array. The system will be

located near the runway center line, extended. The transmitters are 75

MHz, low power units with keyed tone modulation. The units are

controlled via lines from the tower.

The outer marker will be located between 4 and 7 miles in front of th e

approach end of the runway, so the pattern crosses the glide angle at

the intercept altitude. The modulation will be 400 Hz keyed at 2 dashes

per second.

The middle marker will be located about 3500 feet from the approach

end of the runway, so the pattern intersects the glide angle at 200 feet.

The modulation will be a 1300 Hz tone keyed by continuous dot, dash

pattern.

Some ILS runways have an inner marker located about 1.000 feet from

the approach end of the runway, so the pattern intersects the glide

angle at 100 feet. The transmitter is modulated by a tone of 3000 Hz

keyed by continuous dots.

Distance Measuring Equipment (DME):

Where the provision of Marker Beacons is impracticable, a DME can be

installed co-located with the Glide Path facility.

The ILS should be supplemented by sources of guidance information which will

provide effective guidance to the desired course. Locator Beacons, which are

essentially low power NDBs, installed at Outer Marker and Middle Marker

locations will serve this purpose.

Aircraft ILS Component :

The Azimuth and Elevation guidance are provided by the Localizer and Glide

Path respectively to the pilot continuously by an on-board meter called the

Cross Deviation Indicator (CDI).Range information is provided continuously in

the form of digital readout if DME is used with ILS. However range information

is not presented continuously if Marker Beacons are used. In this condition

aural and visual indications of specific distances when the aircraft is overhead

the marker beacons are provided by means of audio coded signals and lighting

of appropriate colored lamps in the cockpit.

FUNCTIONS OF ILS COMPONENTS :

A brief description of each of the ILS components is given in this section.

Function of Localizer unit :

The function of the Localizer unit is to provide, within its coverage

limits, a vertical plane – o f c o u r s e a l i g n e d with the extended

center-line of the runway for azimuth guidance to landing aircraft. In

addition, it shall provide information to landing aircraft as to whether

the aircraft is offset towards the left or right side of this plane so as

to enable the pilot to align with the course.

Function of Glide Path unit :

The function of the Glide Path unit is to provide, within its coverage limits, an

inclined plane aligned with the glide path of the runway for providing elevation

guidance to landing aircraft. In addition, it shall provide information to landing

aircraft as to whether the aircraft is offset above or below this plane so as to

enable the pilot to align with the glide path.

Function of marker Beacon / DME :

The function of the marker beacons,/DME is to provide distance information

from the touch down point to a landing aircraft.

The marker beacons, installed at fixed distances from the runway threshold,

provide specific distance information whenever a landing aircraft is passing

over any of these beacons so that the pilot can check his altitude and correct it if

necessary.

The DME, installed co-located with the Glide Path unit, will provide a continuous

distance information from the touch down point to landing aircraft.

Function of Locators:

The function of locators, installed co-located with the marker beacons, is to

guide aircraft coming for landing to begin an ILS approach.

Different models used in AAI:

Different models of ILS used in AAI are as follows:

1. GCEL ILS :In this ILS mechanical modulator is used and both the near field monitoring system is utilized.

2. NORMARC ILS :In this system advance technology is used and for monitoring purpose along with near field monitoring integral monitoring has been utilized .Now a days 2 models viz. NM 3000 series and NM 7000 series are mostly used in AAI.

3. ASI ILS : In Mumbai and Delhi airport these ILS are used under modernization programme. One of the ILS model at Delhi is a CAT III ILS.

GENERAL CONCEPTS ON

SECURITY EQUIPMENTS

&

PUBLIC ADDRESS SYSTEM

MULTI ENERGY MACHINES

The machine used in airports usually is based on a dual-energy X-ray system.

This system has a single X-ray source sending out X-rays, typically in the range

of 140 to 160 kilovolt peak (KVP). KVP refers to the amount of penetration an

X-ray makes. The higher the KVP, the further the X-ray penetrates.

After the X-rays pass through the item, they are picked up by a detector. This

detector then passes the X-rays on to a filter, which blocks out the lower-

energy X-rays. The remaining high-energy X-rays hit a second detector. A

computer circuit compares the pick-ups of the two detectors to better

represent low-energy objects, such as most organic materials.

Since different materials absorb X-rays at different levels, the image on the

monitor lets the machine operator see distinct items inside your bag. Items are

typically colored on the display monitor, based on the range of energy that

passes through the object, to represent one of three main categories:

1. Organic 2. Inorganic 3. Metal

While the colours used to signify "inorganic" and "metal" may vary between

manufacturers, all X-ray systems use shades of orange to represent "organic."

This is because most explosives are organic. Machine operators are trained to

look for suspicious items -- and not just obviously suspicious items like guns or

knives, but also anything that could be a component of an improvised

explosive device (IED). Since there is no such thing as a commercially available

bomb, IEDs are the way most terrorists and hijackers gain control. An IED can

be made in an astounding variety of ways, from basic pipe bombs to

sophisticated, electronically-controlled component bombs.

While the colours used to signify "inorganic" and "metal" may vary between manufacturers, all X-ray systems use shades of orange to represent "organic."

This is because most explosives are organic. Machine operators are trained to look for suspicious items -- and not just o also anything that could be a

component of an improvised explosive device (IED). Since there is no such thing as a commercially available bomb, IEDs are the way most terrorists and

hijackers gain control. An IED can be made in an astounding variety of ways,

from basic pipe bombs to sophisticated, electronically-controlled component bombs.

While the colors used to signify "inorganic" and "metal" may vary between

manufacturers, all X-ray systems use shades of orange to represent "organic." This is because most explosives are organic. Machine operators are trained to

look for suspicious items -- and not just obviously suspicious items like guns or knives, but also anything that could be a component of an improvised explosive

device (IED). Since there is no such thing as a commercially available bomb, IEDs are the way most terrorists and hijackers gain control. An IED can be

made in an astounding variety of ways, from basic pipe bombs to sophisticated, electronically-controlled component bombs.

WORKING PRINCIPLE

Nature of X-rays X-rays are electromagnetic waves whose wavelengths

range from about (0.1 to 100)x 10-10 m. They are produced when

rapidly moving electrons strike a solid target and their kinetic energy

is converted into radiation. The wavelength of the emitted radiation

depends on the energy of the electrons.

Production of X-Rays There are two principal mechanisms by which x-rays are

produced. The first mechanism involves the rapid deceleration of a

high-speed electron as it enters the electrical field of a nucleus.

During this process the electron is deflected and emits a photon of x-

radiation. This type of x-ray is often referred to as bremsstrahlung or

"braking radiation". For a given source of electrons, a continuous

spectrum of bremsstrahlung will be produced up to the maximum

energy of the electrons.

The second mechanism by which x-rays are produced is through

transitions of electrons between atomic orbits. Such transitions

involve the movement of electrons from outer orbits to vacancies

within inner orbits. In making such transitions, electrons emit

photons of x-radiation with discrete energies given by the differences

in energy states at the beginning and the end of the transition.

Because such x-rays are distinctive for the particular element and

transition, they are called characteristic x-rays.

Both of these basic mechanisms are involved in the production of x-

rays in an x-ray tube. Figure 1 is a schematic diagram of a standard x-

ray tube. A tungsten filament is heated to 20000C to emit electrons.

A very high voltage is placed across the electrodes in the two ends of

the tube and the tube is evacuated to a low pressure, about 1/1 000

mm of mercury. These electrons are accelerated in an electric field

toward a target, which could be tungsten also (or more likely copper

or molybdenum for analytical systems). The interaction of electrons

in the target results in the emission of a continuous bremsstrahlung

spectrum along with characteristic x-rays from the particular target

material. Unlike diagnostic x-ray equipment, which primarily utilize

the bremsstrahlung x-rays, analytical x-ray systems make use of the

characteristic x-rays.

INTRODUCTION TO AIRPORT METAL DETECTORS

Old metal detectors worked on energy absorption principle used two coils as search coils, these were forming two loops of a blocking oscillator. When any person carrying a metallic object or a weapon stepped through the door carrying

coils, some energy was absorbed and the equilibrium of the blocking oscillator got disrupted. This change was converted into audio and visual indications. Size

and weight of the metallic object was determined by proper sensitivity settings.

The hand held metal detectors used the same technique. These type of metal detectors carried various shortcomings and they have been superseded by new

generation multi zone equipments working on PI technology

TYPES- The metal detectors, used in aviation sector are generally of two types.

1. HAND HELD METAL DETECTORS

2. DOOR FRAME METAL DETECTORS

1.MELU 5087 M28

Electronics unit

2.METOR coil set

3. 8.Button M28

4.Carring strap

5.Button slide

6. Battery/ charger cable

7.Clamping screw

8.Frame M28

9.Button extender hose

10 Cover M28

11. Battery cover

HAND HELD METAL DETECTOR

(HHMD)

4 Detailed block diagram description

OPERATION

The coil is part of the oscillating circuit which operation frequency is 23.5

kHz. When a metal object is inside the sensing area of the coil, it will

effect to amplitude of the oscillating signal. After a while the integrating

control will set the amplitude a constant value.

Output of oscillator is rectified and it is connected through the filter

section to comparator. When the signal is lower than the adjusted

reference level (sensitivity setting) comparator generates alarm signal.

It activates the alarm oscillator and the audible alarm / the red alarm

light.

Battery voltage is controlled with a low voltage circuit and constant

alarm is activated when the battery voltage is under 7V.

The connector in the rear of the unit operates as headphone and

charger connections. The charger idle voltage is between 14 and 24

VDC. During charging operation the green light is plinking and with full

battery it lights constantly. If headphone is connected, audible alarm is

not operational.

DOOR FRAME METAL DETECTORS

Almost all airport metal detectors are based on pulse induction (PI). Typical PI systems use a coil of wire on one side of the arch as the transmitter and receiver.

This technology sends powerful, short bursts (pulses) of current through the coil of wire. Each pulse generates a brief magnetic field. When the pulse ends, the

magnetic field reverses polarity and collapses very suddenly, resulting in a sharp electrical spike. This spike lasts a few microseconds (millionths of a second) and causes another current to run through the coil. This subsequent current is called the reflected pulse and lasts only about 30 microseconds.

Another pulse is then sent and the process repeats. A typical PI-based metal detector sends about 100 pulses per second, but the number can vary greatly

based on the manufacturer and model, ranging from about 25 pulses per second to over 1,000 If a metal object passes through the metal detector, the pulse

creates an opposite magnetic field in the object. When the pulse's magnetic field collapses, causing the reflected pulse, the magnetic field of the object makes it

take longer for the reflected pulse to completely disappear. This process works something like echoes: If you yell in a room with only a few hard surfaces, you

probably hear only a very brief echo, or you may not hear one at all. But if you yell into a room with a lot of hard surfaces, the echo lasts longer. In a PI metal

detector, the magnetic fields from target objects add their "echo" to the reflected pulse, making it last a fraction longer than it would without them.

A sampling circuit in the metal detector is set to monitor the length of the

reflected pulse. By comparing it to the expected length, the circuit can determine if another magnetic field has caused the reflected pulse to take longer

to decay. If the decay of the reflected pulse takes more than a few microseconds longer than normal, there is probably a metal object interfering with it.

The sampling circuit sends the tiny, weak signals that it monitors to a device

call an integrator. The integrator reads the signals from the sampling circuit, amplifying and converting them to direct current (DC).The DC's voltage is

connected to an audio circuit, where it is changed into a tone that the metal detector uses to indicate that a target object has been found. If an item is found, you are asked to remove any metal objects from your person and step through

again. If the metal detector continues to indicate the presence of metal, the attendant uses a handheld detector, based on the same PI technology, to isolate

the cause.

Many of the newer metal detectors on the market are multi-zone. This means that they have multiple transmit and receive coils, each one at a different height.

Basically, it's like having several metal detectors in a single unit.

METOR 200 (PRINCIPLE OF OPERATION)

The transmitter coils generate a pulsed magnetic field around them. Metal

objects taken through the detector generate a secondary magnetic field, which

is converted into a voltage level by the receiver coils. Metor 200 consists of

eight separate overlapping transmitter and receiver coil pairs. The signal

received from each receiver coil are processed individually thus the transmitter

and receiver coil pairs form eight individual metal detectors. The operation is

based on electromagnetic pulsed field technology as below in addition to the

above explanation.

Transmitter pulses cause decaying eddy currents in metal objects inside the sensing area of the WTMD

The signal induced to the receiver by the eddy currents is sampled and

processed in the electronics unit.

Moving metal objects are detected when the signal exceeds the alarm

threshold.

METOR 200

Eight overlapping detection zones

METOR 200 is a multi-channel metal detector with eight overlapping detection zones. The zones create a sequential pulsating magnetic field within the

detection area of the WTMD.

With overlapping construction, sensitivity differences are minimised when metal objects of different shape pass through the WTMD in various orientations

Metal objects at different heights are detected separately by the individual

detection zones producing superior discrimination.

Advanced microprocessor technology is used for digital signal processing and internal controls. This provides reliable functioning of the metal detector,

versatile features and user friendly operations.

The electronics unit processes the signals received from the receiver coils. It indicates the result of the signal processing through an alphanumerical display, alarm LEDs and Buzzer. The zone display unit, which is mounted on transmitter

coil panel, points out the position where a weapon was taken through the gate. The user controls the functions of the metal detector with a remote control

unit. It sends to the electronics unit an IR signal corresponding to the pressed keyboard code.

The traffic counter counts the number of persons walking through the gate and the amount of alarms generated.

ATS AUTOMATION SYSTEM

General System Description One of the main characteristics of the system is its availability, due to the employment of redundant elements on a distributed scenario, and to the use of tested and highly reliable commercial equipment. The software architecture of the system is determined by its modularity and distribution and has been organized using distributed discrete processes for the different subsystems. At the same time, the system makes use of communication by messages, both for intercommunications between tasks and for its synchronicity. In order to assure a maximum level of maintenance, communications and application tasks have been isolated. The Operating System used is RED HAT ENTERPRISE LINUX 5. This system includes all the necessary functionality required in a modern ATC system. Its main elements are following described: The integration of all its subsystems is performed via:

Local Area Network (LAN). A redundant five (5) category with a 1-Gigabyte bandwidth capacity LAN is used and, therefore, future updates of the system can be easily implemented making use of standard communication protocols.

Main components:

Flight Data Processing (FDP). It is based on INTEL redundant computers. It manages the flight plans generated within the System or coming from external sources, including the Repetitive Flight Plans (RPLs). It confirms all flight data inputs, calculates the flights’ progression and keeps all controllers inform by means of screen displays and flight plan strips printing. The System is designed in redundant configuration, having an FDP as operative and another one as reserve, with the possibility to switch them.

Surveillance Data Processor (SDP). It is based on INTEL redundant computers. It receives and processes data (primary, secondary and meteorological) coming from the radar sites. Next, it performs the merge all the received information to create a coherent airspace picture for controllers’ (SDD) presentation. It also performs surveillance tasks (STCA, MTCD) between aircraft and integrates the radar information and the flight plan information in order to get a precise tracking. The System is duplicated (operative/reserve) being possible to switch them. Attempting to the Tower type the system shall provide or not the SDP servers.

Radar Communications Processor (RDCU). It centralizes the System radar communications to interpret and convert the received radar formats to join them. The System is composed of two RDCU units working parallel. It is possible to carry out the received radar data reproduction during an established period.

Controlling positions:-

Situation Data Display (SDD). It receive data processed by FDP. Later on, it manages all these information for a coherent displaying at the controllers screens (SDD). At the same time, it displays additional relevant information such as geographic maps, meteorological data, radar data, and flight plans presentations shown on the controller screens and it can show additional information like geographical maps, airways, meteorological data, etc.

Flight Data Display (FDD). It displays information concerning flight plans not supplying data display of data on air situation. It allows controllers to perform adjustments on flight plans and other significant data.Its aim is to provide a work environment to the operational personnel of the Air Traffic Control Centre for flight plans handling. This environment consists

of an HMI computer (screen, mouse and keyboard) connected to the subsystem that manages Flight Plans so that the entire flight plan related information is easily reachable by the operator. The FDD Position allows the controller mainly to handle flight plans during the strategic planning phase. That is, the controller of this position manages future flight plans (Flight plans received trough AFTN and Repetitive Flight Plans (RPL)).

Control and Monitoring Display (CMD). The Control and Monitoring Display Position (CMD) is one of the components of the Tower and Approach Integrated System. Its main aim is to offer help to technical staff in the Traffic Control Centre, providing a work environment able to monitor the whole system in an easy but precise way in real time. For that reason, the position is connected to the other subsystems. Its main element is a computer with screen, mouse and keyboard.It continuously monitors the whole system and shows its status in real time. When a components fails or is not working correctly, an operator can take the appropriate actions on the CMD console. Some system parameters can be changed trough the CMD to adequate the system configuration to the actual working conditions, as they can be the VSP parameters or active sectorization.

Auxiliary equipment:

Common Timing Facility (CTF). It receives the GPS time, which is spread to all the subsystem (via LAN) and all clocks (via Terminals) with NTP protocol.

Data Recording Facilities (DRF). The Data Recording and Playback Position (DRF) is one of the elements of the Tower and Approach Integrated Control System. The main duties of this position are the recording of all relevant data in a convenient order and their subsequent recognition and playback. The DRFs is a utility for recording and playbacking. The information of SDDs is saved on tapes. The process is: 1. SDDs record all data in local files. The data are: Events, monitoring, etc. This data files are sent to the DRFs each hour automatically. 2. When the DRFs receive the files from the SDDs, these ones are recorded on tapes. 3. The DRFs displays to technical staff all files received from the SDDs on a screen as well all files save on tapes. Also, the DRFs allow monitoring the tapes states, the recorder files, used capacity tapes.

This component records continuously all the data related to the tracks data, flight plans data, and the controller actions to allow later playback and analysis. To reproduce information stored in tape it would be enough with: 1st: To gather the necessary files stored in tape. This operation is carried out by means of an intuitive graphic interface. 2nd: The DRF will take charge loading the above mentioned information in the SDD specified by the technician for his later reproduction.

Data Base Management (DBM). It provides the necessary facilities the creation and modification of the adaptation databases to supply the system with the precise knowledge of its geographical environment to achieve the required efficiency. From this database, all necessary data to define the control centre characteristics are defined (fixpoints, aerodromes, airways, sectorization, adjacent control centres, QNH zones, etc.)

Multichannel Signal Recorder / Neptuno 4000 The Neptuno 4000 is a multi-channel signal recording. Neptuno 4000 performs the sampling of multiple analogue and/or digital channels, with variable bandwidth and quality requirements. The sampled signals are stored digitally, and can be replayed, transmitted, routed or edited.

ADS-B

Definition

A means by which aircraft, aerodrome vehicles and otherobjects can

automatically transmit and /or receive data such as

identification,position and additional data , as appropriate, in a

broadcast mode via datalink.

Theory Of Operation

The ADS-B system enables the automatic broadcast of an aircraft’s

identity,position, altitude, speed, and other parameters at half-second

intervals usinginputs such as a barometric encoder and GNSS equipment

The result is afunctionality similar to SSR. Under ADS-B, a target

periodically broadcasts itsown state vector and other information

without knowing what other entitiesmight be receiving it, and without

expectation of an acknowledgment or reply.ADS-B aircraft transmissions

received by a network of ground stations canprovide surveillance over a

wider area. Referred to as ADS-B OUT, this providesATC with the ability

to accurately track participating aircraft.

ADS-B is automatic because no external stimulus is required; it

isdependent because it relies on on-board position sources and on-

boardbroadcast transmission systems to provide surveillance

information to otherparties. Finally, the data is broadcast, the

originating source has no knowledgeof who receives and uses the data

and there is no two-way contract orinterrogation.

Categories of Networks

Today when we speak of networks, we are generally referring to three primary categories:

local area networks, metropolitan area networks, and wide area networks. In which category

a network falls is determined by its size. its ownership, the distance it covers, and its

physical architecture (see Figure below).

Figure: Categories of network

Local Area Network (LAN)

A local area network (LAN) is usually privately owned and links the devices in a single office,

building, or campus (see Figure below).

Depending on the needs of an organization and the type of technology used, a LAN can be

as simple as two PCs and a printer in someone's home office; or it can extend throughout a

company and include audio and video peripherals. Currently, LAN size is limited to a few

kilometers.

LANs are designed to allow resources to be shared between personal computers or

workstations. The resources to be shared can include hardware (e.g., a printer), software

(e.g., an application program), or data. One of the computers may be given a large capacity

disk drive and may become a server to the other clients. Software can be stored on this

central server and used as needed by the whole group. In this example, the size of the LAN

may be determined by licensing restrictions on the number of users per copy of software, or

by restrictions on the number of users licensed to access the operating system.

In addition to size, LANs are distinguished from other types of networks by their

transmission media and topology. In general, a given LAN will use only one type of

transmission medium. The most common LAN topologies are bus, ring, and star.

Traditionally, LANs have data rates in the 4 to 16 megabits per second (Mbps) range.

Today, however, speeds are increasing and can reach 100 Mbps with gigabit systems in

development. The local area networks can also be subdivided according to their media

access methods. The well-known media access methods are: Ethernet or CSMA/CD, Token

Ring and Token Bus. The Ethernet LAN used in ECIL AMSS is discussed in detail later in

this Chapter.

Wide Area Network (WAN)

A wide area network (WAN) provides long-distance transmission of data, voice, image, and video

information over large geographic areas that may comprise a country, a continent, or even the

whole world (see figure below).

Figure: WAN

In contrast to LANs (which depend on their own hardware for transmission), WANs may

utilize public, leased, or private communication equipment, usually in combinations, and can

therefore span an unlimited number of miles.

A WAN that is wholly owned and used by a single company is often referred to as an

enterprise network

The Internet is built on the foundation of TCP/IP suite. The dramatic growth of the

Internet and especially the World Wide Web has cemented the victory of TCP/IP over OSI.

TCP/IP comprises of five layers:

Application Layer

Transport/TCP Layer

IP/Network layer

Network Access/Link Layer

Physical Layer. Internet Address

The identifier used in the network layer of the Internet model to identify each device

connected to the Internet is called the Internet address or IP address. An IP address, in the

current version of the protocol (IP Version 4) is a 32-bit binary address that uniquely and

universally defines the connection of a host or a router to the Internet.

IP addresses are unique. They are unique in the sense that each address defines

one, and only one, connection to the Internet. Two devices on the Internet can never have

the same address at the same time. However, if a device has two connections to the

Internet, via two networks, it has two IP addresses.

The IP addresses are universal in the sense that the addressing system must be

accepted by any host that wants to be connected to the Internet.

There are two common notations to show an IP address: binary notation and dotted decimal

notation.

Binary Notation

In binary notation, the IP address is displayed as 32 bits. To make the address lIl(J readable,

one or more spaces is usually inserted between each octet (8 bits). Each <XI! is often

referred to as a byte. So it is common to hear an IP address referred to as 32-bit address, a

4-octet address, or a 4-byte address. The following is an example an IP address in binary

notation:

01110101 10010101 00011101 11101010

Dotted-Decimal Notation

To make the IP address more compact and easier to read, Internet addresses are usually

written in decimal form with a decimal point (dot) separating the bytes. Figure below shows

an IP address in dotted-decimal notation. Note that because each byte (octet) only 8 bits,

each number in the dotted-decimal notation is between 0 and 255.

Figure: Dotted-decimal notation

Classful Addressing

IP addresses, when started a few decades ago, used the concept of classes. This archi-

tecture is called classful addressing. In the mid-1990s, a new architecture, called classless

addressing, was introduced which will eventually supersede the original architecture.

However, most of the Internet is still using classful addressing, and the migration is slow.

In classful addressing, the IP address space is divided into five classes: classes A, B,

C, D, and E. Each class occupies some part of the whole address space. The following

figure shows the address ranges of these five classes of network.

Addresses in classes A, B, and C are for unicast communication, from one source to one

destination. A host needs to have at least one unicast address to be able to send or receive

packets.

Addresses in class D are for multicast communication, from one source to a group of

destinations. If a host belongs to a group or groups, it may have one or more multicast

addresses. A multicast address can be used only as a destination address, but never as a

source address.

Addresses in class E are reserved. The original idea was to use them for special

purposes. They have been used only in a few cases.

Netid and Hostid

In classful addressing, an IP address in classes A, B, and C is divided into netid and hostid. These p arts

are of varying lengths, depending on the class of the address. The following figure shows the netid

and hostid bytes.

The numbers 0,127,255 have some special meaning in TCP/IP.

Every network itself has an address. For example if a computer in a network has an

address of 191.56.56.13 the network address is 191.56.0.0.

Every network needs a separate broadcast address. Network access layer uses it

to broadcast an ARP request to determine the destination’s MAC address. For

191.56.56.13 the broadcast address is 191.56.255.255.

A separate address is for local loop back that is 127.0.0.1. PING command uses

this for local connectivity.

SUBNET MASK

Subnet mask defines network address part and host/computer address part of an

IP address. For the subnet address scheme to work, every machine on the

network must know which part of the host address will be used as the subnet

address. This is accomplished by assigning a subnet mask to each machine. A

subnet mask is a 32-bit value that allows the recipient of IP packets to distinguish

the network ID portion of the IP address from the host ID portion of the IP

address. The network administrator creates a 32-bit subnet mask composed of

1s and 0s. The 1s in the subnet mask represent the positions that refer to the

network or subnet addresses. Not all networks need subnets, meaning they use

the default subnet mask. This is basically the same as saying that a network

doesn't have a subnet address. Table below shows the default subnet masks for

Classes A, B, and C.

CLASS A

255.0.0.0

CLASS B 255.255.0.0

CLASS C 255.255.255.0

Figure: TCP/IP Protocol Suite