Training Report Abhishek Gupta

8/3/2019 Training Report Abhishek Gupta

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COMMUNICATION NAVIGATION SURVEILLANCE (CNS)

A

TRAINING REPORT

submitted

in partial fulfillment

for the award of the Degree of

Bachelor of Technology

in Department of Electronics and CommunicationEngineering

ACADEMIC SESSION

20112012

Submitted By: Submitted To:

Name: Abhishek Gupta Mrs. Preeti Vohra

Roll No.: 09-ECE-1403 Sr. Lecturer

Sem: Vth

Echelon Institute of Technology

Faridabad


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ACKNOWLEDGEMENT

I extend my sincere thanks to Ms. Renu Agarwal, Director, T&P Cell for

allowing me to pursue my summer training at Airports Authority Of India.

I am immensely thankful to Mr. S.K. Tom ar, G.M., RTC, and the entire team

for extending their full support during the training and also guiding me at

each and every step. I would also like to thank them for being the motivation

behind all the work done. All the work would never be possible without their

help.

I also owe my regards to my uncle Mr. Abhijit Banerji for making it possible

for me to pursue my training at AAI.

Atlast, I want to thank my teacher Mrs. Preeti Vohra, Sr. Lecturer for helping

me throughout in preparing this report.


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CONTENTS

CERTIFICATE

AKNOWLEDGEMENT

CONTENTS

INTRODUCTION

BODY OF REPORT

1) AUTOMATION OBJECTIVES TYPES OF EQUIPMENTS ATC WORKING POSITION SYSTEM OVERVIEW

2) NAV-AIDS (DVOR) NON DIRECTIONAL BEACON (NDB) VOR (CVOR AND DVOR) DISTANCE MEASURING EQUIPMENT (DME) INSTRUNMENT LANDING SYSTEM (ILS)

3) AMSS (AUTOMATED MESSAGE SWITCHING SYSTEM)

OPERATIONS

HARDWARE CONFIGURATION SOFTWARE CONFIGURATION

4) VHF MODULATION FREQUENCY BAND TYPES OF ANTENNAS


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RADAR

CONCLUSION

APPENDIX

BIBLIOGRAPHY


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INTRODUCTION

The AIRPORTS AUTHORITY OF INDIA (AAI) is an organization working under the

Ministry of Civil Aviation that manages all the airports in India. AIRPORTS AUTHORITY

OF INDIA (AAI) came to existence on 1st

April 1995. It was formed under the act of

parliament (AIRPORTS AUTHORITY OF INDIA ACT 1994) by merging the

INTERNATIONAL AIRPORTS AUTHORITY OF INDIA and NATIONAL AIRPORTS

AUTHORITY with a view to accelerate the integrated development, expansion and

modernization of the air traffic services, passenger terminals, operational areas and cargo

facilities at the airports in the country.

The AAI manages and operates 126 airports including 11 international airports, 89 domestic

airports and 26 civil enclaves. The corporate headquarters (CHQ) are at Rajiv Gandhi

Bhawan , Safdarjung Airport, New Delhi.

V.P. Aggarwal is the current chairman of the AAI. Presently, it is owned 100% by the

Government of India.


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MAIN FUNCTIONS OF AAI

1.) Control and management of the Indian air space extending beyond the territorial limits

of the country.

2.) Provision of communication, navigation and surveillance aids.

3.) Expansion and strengthening of operational areas and movement control aids for

aircrafts and vehicular traffic in operational areas.

4.) Design, development, operation and maintenance of passenger terminals.

5.) Development and management of cargo terminals at international and domestic

airports.

6.) Provision of passenger facilities and information system in passenger terminals.


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SERVICES PROVIDED BY THE AAI

AAI provides two main services:

1.) Air traffic services

2.) Construction and development of airports and air routes

Air traffic services have two main departments that manage different functions.

These are:

1.) Air traffic management

2.) CNS


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CONTACT DETAILS OF THE COMPANY:

Name: Airports Authority of India

Address: Regional Training Centre (NR)

ATS Complex, IGI Airport

New Delhi-110037

Contact No.: 011-25656451

AREA OF TRAINING:

CNS (Communication, Navigation & Surveillance)


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AUTOMATION SYSTEM

Automation system provides the air traffic controller with the information required for thesafe and efficient performance of their duties.

It uses information and data from various systems and equipments and organizes this

information to best accomplish this purpose.

OBJECTIVES:

PRIMARY OBJECTIVES:The primary objectives of automation system are as follows:

1) Efficiency enhancement of ATC officers:Automation system enhances the efficiency of the air traffic controllers.

2) Accuracy of overall ATC:

Automation system also takes care of the accuracy of the air traffic controllers as well as

that of the pilot.

3) Safety of passengers and aircraft:

Efficiency and accuracy of air traffic controllers directly/indirectly leads to safety of the

passengers as well as the aircraft.

ALL THIS IS DONE THROUGH TIMELY ACQUISITION AND PRESENTATION

OF FLIGHT RELATED DATA FOR USE BY AIR

TRAFFIC CONTROLLERS AND SUPPORT STAFF.


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TYPES OF EQUIPMENTS IN THE UNIT

Subsystem Type Subsystem Description Main H/WConfiguration

RDPS Radar data processing

system

SUN FIRE-210

FDPS Flight data processing system SUN FIRE-210

DRF Data recording facility SUN FIRE-210

ATG Air traffic generator

(ATC simulator system)

SUN FIRE-210

SDD Situation display workstation SUN BLADE-2500

FDD Flight data display

workstation

SUN BLADE-1500

CMD Control and Monitoring

display workstation

SUN BLADE-1500

AIS Aeronautical information

system

SUN BLADE-1500

DRA Direct radar access SUN FIRE-210

DMS Database Management

system

SUN BLADE-1500

Dual LAN

Network

Connecting all the

subsystems

CAT-5 e


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ATC WORKING POSITIONS

The ATC working positions are the operational areas from which all air traffic is controlled

and coordinated. The ATC working positions are divided into sectors with each sector being

assigned an area of ATC responsibility (controlling inbound traffic, outbound traffic, etc.).

Each sector consists of one or more operational working positions. The primary objective of

the working position is to provide the man-machine interface between the ATC operational

system and the user (air traffic controller) for the purpose of controlling aircraft. Each

working position is comprised of a combination of the following display types and I/O

devices, depending upon the assigned function: situation data display (SDD), flight data

display (FDD), optical mouse, various keyboards, flight strip printer, and hard copy printer.

AUTOMATION SYSTEM OVERVIEW

The Automation System is comprised of the following functional subsystems:

1 .Local Area Network (LAN)

2 .Time Reference System (TRS)

3 .Radar Data Processing System (RDPS)

4 .Flight Data Processing System (FDPS)

5 .Data Recording Facility (DRF)

6 .Operational Controller Position

7 .Tower Position

8 .Control And Monitoring Display (CMD)

9 .Supervisor Position

10 .Data Management System (DMS)


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1) LAN-Critical subsystem components such as RDPS, FDPS, and DRF, are redundantto ensure continuous operation in the event of a component failure or maintenance

action through LAN Switches. All the subsystems are interconnected via dual 1GB

Ethernet LAN except tower positions which operate on 100MBPS. A third LAN

provides Direct Radar Access (DRA).

2) TIME REFERENCE SYSTEM (TRS)

A Global Positioning Satellite (GPS) based time reference system provides precision

timing information to the Automation System.

TRS typically consists of an antenna, receiver, and a time and frequency processor

module at each server, inputting the timing signal. The antenna picks up the GPS signal,

which is then passed on to the receiver via a coaxial cable.

The receiver puts out an IRIG-B signal, which is sent to the time and frequency processor

module in each of the Radar Data Processing Systems (RDPS). These establish timing for

the Automation System.

3)Radar Data Processing System (RDPS)receives and processes radar data

information from various radar sites.

The main purpose of the RDPS is to process radar data. This includes returns consisting of

both Primary Surveillance Radar(PSR) and Secondary Surveillance Radar (SSR) track

data from detected aircraft. The Radar Data Processor (RDP) filters this data and provides it

to the tracking function, which uses the radar data to update the track data maintained on each

aircraft. The principal outputs of the RDPS are target track and flight plan data, which the

RDPS supplies to the Situation Data Displays (SDDs) via the LAN. The RDPS also generates

status information and reports for display at the Control and Monitoring Display (CMD) and

makes data available for recording at the Data Recording Facility (DRF).


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4) FLIGHT DATA PROCESSING SYSTEM (FDPS)

The main purpose of the FDPS is to create and update flight plans based on information

received from external sources. These external sources of data include inputs from Flight

Data Display(FDD) positions and Air Traffic Services (ATS) messages received via the

Aeronautical Fixed Telecommunications Network (AFTN) interface.

In addition, the FDPS is capable of analyzing flight plan routes, performing flight plan

conversion, calculating flight trajectory and estimated times, determining flight plan status,

validating flight plans, displaying and/or printing flight plan data, providing automatic and

manual Secondary Surveillance Radar (SSR) code allocation, processing Meteorological

(MET) data, and automatically updating flight plans based on Estimated Time Over (ETO)

provided from the Radar Data Processor (RDP).

The FDPS provides redundancy with an active and standby Flight Data Processor (FDP). In

normal operation, one FDP is active and the other is in standby. In the event of failure of the

active FDP, the standby FDP will automatically assume the active functions. The System

Monitoring and Control (SMC) software monitors the health of the FDPS and upon detection

of a failure of the active subsystem, causes a switchover to occur.

5) DATA RECORDING FACILITY (DRF)

The DRF records and allows the replay ofAir Traffic Control (ATC) data. Data is recorded

from all subsystems onto Digital Audio Tape (DAT) and hard disk. Two types of playback

supported by the DRF can be selected at the Control and Monitoring Display (CMD),

either a playback of previously recorded data targeted for a particular playbackSituation

Data Display (SDD), or a printed log of

operator inputs, system messages, and certain list updates as they occurred at the CMD or

Flight Data Display (FDD) workstation positions. SDD playback provides a visual replay of

events recorded as they occurred at the selected SDD. The SDD operator can control the

presentation of the playback data via freeze and unfreeze requests to the DRF.


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For redundancy, there are an active and a standby DRF. In the event of failure of the active

DRF, the standby DRF will automatically assume the active functions.

6) OPERATIONAL CONTROLLER POSITION

The primary function of the Operational Controller Position is to control aircraft that enters

its assigned area of jurisdiction and to monitor aircraft flight plan progress. The position

integrates radar and non-radar ATC functions and communications facilities into a single

console.

7) TOWER POSITION

The primary function of the Tower Position is to monitor air traffic in the immediate area.

8) CONTROL AND MONITORING DISPLAY (CMD)

The CMD console provides an integrated capability for control and monitoring of the

automation components and radar. It provides an interface to the operator so that the operator

may monitor, make changes, or control the system configuration. The operations that may be

performed at a CMD workstation depend on the log in status and the authorization assigned

to the operator at the workstation. The authorizations that may be assigned are technical

supervisor or operational supervisor.

9) SUPERVISOR POSITION


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9.1) Supervisor Position Hardware and Interface Description

The supervisor console typically consists of SDD, and CMD/FDD/AID. Each component

consists of a Sun workstation/server as well as a keyboard and a mouse.

On the SDD, there is a Graphics Card that drives a Display. SDD is described in a previous

section.

On the CMD/FDD/AID a display is connected to the built-in video on the system board. A

printer is connected to the serial port via a custom RS-232 Null Modem cable.

CMD/FDD/AID is described in a previous section.

10) DATA MANAGEMENT SYSTEM (DMS)

The DMS serves as an off-line workstation (not necessary for ATC operation) for generating

and preparing site adaptation parameters that tailor systems operations to a segment. The

graphical user interface permits the creation and modification of geographical data, input and

updating of database records, and inputting archived data files from the DRF. Output to a

printer is also supported.

Data includes airspace files (airport and airways), equipment files (radar and altimeters),

sectorization files, system files (display configurations), and Secondary Surveillance Radar

(SSR) codes.


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NAVIGATIONAL AIDS

NDB: Non Directional Beacon

VOR: VHF Omni Range

DME: Distance Measuring Equipment

ILS: Instrument Landing System

1. Non-directional beacon (NDB)

A Non-directional beacon (NDB) is a radio transmitter at a known location,used as an

aviation or marine navigational aid.

NDB signals follow the curvature of the earth,so they can be received at much greater

distances at lower altitudes, a major advantage over VOR.

The signal transmitted does not include inherent directional information, in contrast to newer

navigational aids such as VHF Omni directional range (VOR).

However, the NDB signal is affected more by atmospheric conditions, mountainous terrain,

coastal refraction and electrical storms, particularly at long range.

NDB usage for aviation is standardized by ICAO which specifies that NDBs be operated on a

frequency between 190 kHz and 1750 kHz.

NDB navigation consists of two parts:


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1. NDB transmitter

2. Automatic Direction Finding (or ADF) equipment on the aircraft that detects an

NDB's signal.

Direction Finder (NDB)

Uses of non-directional beacons:

1. Homing PurposeNDB is also used for homing purpose where the aircrafts knows its spherical co-ordinates

w.r.t north when it tunes into the particular frequency of the NDB in concern.

2. Holding PurposeThe range and level is assigned by NDB located at that area when there are many aircrafts

scheduled to land which are assigned a landing no. and held in queue.


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3. EnrouteNDB are most widely used to provide enroute facility to the aircrafts.

Advantages:

The NDB is a simpler equipment to handle with less tuning and maintenance, as

compared to other Navigation aids.

Quite economical in use.

A simple airborne receiver is required to sample its radiation.

2. VHF Omni Range (VOR)

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.

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.


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There are two types of VOR :-

1. Conventional VOR (C-VOR)2. Doppler VOR (D-VOR).

Even though both serve the same purpose as far as the aircrafts are concerned, D-VOR is more accurate than C-VOR but it is costlier than C-VOR.

The error due to the reflections in the variable signal is almost negligible.This is dueto the fact that the variable signal obtained in the receiver is the result of Frequency

modulated sidebands due to the Doppler effect.

Siting criteria for DVOR installation is very much less critical than the conventionalVOR.

PURPOSE AND USES OF VOR:

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.


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VOR enables the Air Traffic Controllers to monitor whether aircraft are following the radials

correctly or not.

Operation of the VOR is based on the phase difference between two 30 Hz signals modulated

on the carrier, called the reference phase and the variable phase. Aircraft determines its

bearing by comparing phase of reference 30 Hz and variable 30 Hz signals.

The reference 30 Hz signal and variable 30 Hz signal are in the same phase in the direction of

magnetic north. In fact this direction is taken as zero degree for VOR and other azimuth

angles measured in clockwise direction.

VOR can be collocated with DME to provide distance information in addition to bearing

data.

Aircraft in NW quadrant with VOR indicator shading

heading from 360 to 090 degrees.


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3. Distance Measuring Equipment (DME)

Distance Measuring Equipment (DME) is a transponder-based radio navigation technology

that measures distance by timing the propagation delay of radio signals.

DME EQUIPMENT PROVIDES SLANT DISTANCE of the AIRCRAFT from GROUND

EQUIPMENT.

Frequency Band allocated for DME: 960 MHz - 1215 MHz leaving 2 MHz on either side of

the band. This resultant band of 962 MHz -1213 MHz is divided into 126 one-MHz channels

for interrogation, and 126 one-MHz channels for transponder replies with the interrogation

frequency and reply frequency always differing by 63 MHz.

DME frequencies are paired to VHF Omni directional range (VOR) frequencies. A DME

interrogator is designed to automatically tune to the corresponding frequency when the

associated VOR is selected.

Operation:

Aircraft uses DME to determine their distance from a land-based transponder by sending and

receiving pulse pairs - two pulses of fixed duration and separation.

The DME system is composed of a UHF transmitter/receiver (interrogator) the aircraft and a

UHF receiver/transmitter (Transponder) on the ground.

The operating principle of DME systems is based on the Radar principle i.e., the time

required for a radio pulse signal to travel to a given point and return.


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Airborne transmitter repeatedly initiates a process of sending out very short, very widely

spaced interrogation pulses.

These are picked up by the ground transponder receiver whose output triggers the

associated transmitter into sending out reply pulses on a different channel.

The airborne receiver receives these replies.

Timing circuits automatically measure the round trip travel time, or interval between

interrogation and reply pulses, and convert this time into electrical signals, which operate the

distance indicator.


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RANGE CALCULATION:

The range, in nautical miles, between the aircraft and the transponder is obtained by the

simple

formula:

Total time (sec) - time delay (sec)

Range = ------------------------------------------------

12.36

The denominator 12.36 sec is the time taken by the pulse to travel 1 nautical mile to and fro.

This time is also called Radar Mile.

Navigation Fix:

DME's use as a navigation aid is based on the principles ofRho-Theta Navigation System.

The Rho-Theta Navigation System is based on the Polar coordinate system of azimuth and

distance.

The Very High Frequency Omni Range (VOR) and DME constitute the basic components of

the Rho-Theta Navigation System. While the VOR provides azimuth information (Theta) to

the pilot, the DME provides the distance information (Rho) so that the pilot receives a

continuous navigational fix relative to a known ground location.


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Modes

There are two modes of aircraft interrogations:

Search Mode

Track Mode.

Search mode is automatically established whenever the airborne equipment is tuned to a new

DME ground Transponder. When the aircraft's transmitter is in Search mode, it transmits

interrogations at a higher rate (about 150 interrogations per second).

When the aircraft receives at least 65% replies to its interrogations Lock-on will be

established and the transmitter changes to the Track mode of operation. This process may

take up to 30 seconds. Only when this is achieved, the cockpit readout of the DME range is

turned on. In the Track mode the aircraft's interrogation rate reduces considerably (about 30

interrogations per second). The reduced interrogation rate of transmission in the track mode

will allow more aircraft to use the DME station.

Uses of DME Installation

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 thesame altitude facilitating reduced separation thereby increasing the aircraft handling

capacity.

Expedite the radar identification of aircraft.


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Provide DME distance in lieu of fan marker beacons and radio range intersections inconnection with instrument approaches and holding operations respectively.

4. Instrument Landing System (ILS)

An instrument landing system (ILS) is a ground-basedinstrument approachsystem that

provides precision guidance to anaircraftapproaching and landing on arunway, using a

combination of radio signals and, in many cases, high-intensity lighting arrays to enable a

safe landing duringinstrument meteorological conditions (IMC), such as lowceilingsor

reduced visibility due to fog, rain, or blowing snow.

COMPONENTS OF INSTRUMENT LANDING SYSTEM

1. LOCALIZER

2. GLIDE PATH

3. LOW POWER DME (CO-LOCATED WITH GLIDE PATH)

4. MARKER BEACONS
http://en.wikipedia.org/wiki/Instrument_approachhttp://en.wikipedia.org/wiki/Instrument_approachhttp://en.wikipedia.org/wiki/Instrument_approachhttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Runwayhttp://en.wikipedia.org/wiki/Runwayhttp://en.wikipedia.org/wiki/Runwayhttp://en.wikipedia.org/wiki/Instrument_meteorological_conditionshttp://en.wikipedia.org/wiki/Instrument_meteorological_conditionshttp://en.wikipedia.org/wiki/Instrument_meteorological_conditionshttp://en.wikipedia.org/wiki/Flight_ceilinghttp://en.wikipedia.org/wiki/Flight_ceilinghttp://en.wikipedia.org/wiki/Flight_ceilinghttp://en.wikipedia.org/wiki/Flight_ceilinghttp://en.wikipedia.org/wiki/Instrument_meteorological_conditionshttp://en.wikipedia.org/wiki/Runwayhttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Instrument_approach


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Localizer

Localizer Frequency:

Total No. of ILS Channels: 40

Carrier Frequency range 108 MHz - 112 MHz


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LOCALIZER EQUIPMENT PROVIDE AZIMUTHAL GUIDANCE i.e. CENTRE LINE of

RUNWAY to a LANDING AIRCRAFT.

Glide Path

Glide Path Frequency Band: 328336 MHz.

GLIDE PATH EQUIPMENT PROVIDE VERTICAL GUIDANCE i.e. GLIDE SLOPE on

RUNWAY to a LANDING AIRCRAFT.


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DME equipment colocated with Glidepath

DME EQUIPMENT COLOCALTED WITH GLIDEPATH PROVIDE SLANT DISTANCE

OF AIRCRAFT FROM RUNWAY TOUCH DOWN POINT.

Marker

Marker Frequency: 75 MHz.

MARKER EQUIPMENTS INSTALLED AT FIX DISTANCES from RUNWAY

THRESHOLD

PROVIDE HEIGHT OVER MARKER which help to ESTABLISH ON CORRECT GLIDE

PATH.


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Guidance tones:

ILS employs amplitude modulation of a radio frequency carrier to provide the guidance

information.

The modulating signals used in ILS are pure sine waves of 90 Hz and 150 Hz frequency.

In Localizer, Modulation frequencies of 90 and 150 Hz are used to provide right and left

indication.

When approaching for a landing, the 150 signal predominates on the right-hand side of the

course and the 90 on the left.

In Glide Path, Modulation frequencies of 90 and 150 Hz are used to provide up and down

indication.

When approaching for a landing, the 150 signal predominates below the glide path and the

90 above.


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The emission patterns of the localizer and glide slope signals. Note that the glide slope beams

are partly formed by the reflection of the glide slope aerial in the ground plane.

The system uses Amplitude Modulation and hence the aircraft receiver must measure thedifference in amplitudes of the detected tones to determine the aircraft position.

This leads to the term: Difference in Depth of Modulation (DDM).

The localizer receiver on the aircraft measures the Difference in the Depth of Modulation

(DDM) of the 90 Hz and 150 Hz signals.

For the localizer, the depth of modulation for each of the modulating frequencies is 20

percent.

The difference between the two signals varies depending on the position of the approaching

aircraft from the centerline.


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If there is a predominance of either 90 Hz or 150 Hz modulation, the aircraft is off the

localizer range.

Similarly, the glide path equipment located next to the length of runway also transmits two

narrow beams from separate but co-located antennas.

One of the beams is slightly above the touch down angle and the other is slightly down of

the touch down angle.

The glide path receiver measures the Difference in the Depth of Modulation.

When there is a predominance of either 90Hz or 150Hz modulation, the aircraft is off the

Glide path range.

When the DDM is zero, the aircraft is correctly positioned.


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When a DDM exists, the pilot must correct the aircraft's position until the DDM is zero.

The pointer needles of the CDI instrument are driven by the DDM.


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Outer Marker:

Located between 4 and 7 miles in front of the 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.

Middle Marker:

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.

Inner Marker:

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.


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AMSS-OPERATIONS

To run the workstations, user-friendly application software on windows 2000 has been

designed by ECIL in accordance with ICAO Annex-10 Vol. II. The application supportsnew and old AFTN message format. The application has been divided into two parts viz.

FRONTEND and BACKEND application.

FRONTEND APPLICATION

The front-end application supports a workstations hardware and the LAN System in the

AMSS environment. The front-end supports different AFTN message preparation features

and queries at workstations viz. NOTAM, ASBS, HFRT etc. customized following execution

files (.exe files) according to the requirement of individual workstation.

NOTAM: notice to airman, these are messages sent to inform about facilities which are

accepted at the airport but are not available due to some reason.

ASBS: Automatic Self-Briefing System, is an application dedicated for the pilots. It

delivers to them all the necessary details of the destination, flight plan and NOTAM

messages relevant for the flight.

X-SERVER: a dedicated PC meant for handling X.25 frame relay messages. Installed into

it are two ECION cards (having 2 ports each) which communicate using frame relay

method.

TCP/IP: a dedicated PC which is used to bridge between the two LANs present AMSS

Delhi center.

HFRT

AREA

SUPERVISOR: two PCs used for monitoring the work of the AMSS. Error messages

involving communication problems are reported to these stations.


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RPL: this terminal is used for uploading of the RPL data into the database.

BACKEND APPLICATION

These applications run in the background controlling the major databases. These run

automatically accepting any data received from LAN, checking validity (as in case of

database servers) and generating timely information in predetermined pattern. Backend

application for database Server sorts the messages received viz. NOTAM, met messages,

ADC/FIC messages, flight plans etc. and stores it is the appropriate database.

Another backend application running is the RPL database, an automatic system which

generates flight plans for scheduled aircrafts before six hours of the flight. This reduces

the human intervention and errors. RPL uses database JKC for all the information it needs

for generating flight plans.


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AMSS HARDWARE CONFIGURATION & COMPONENTS

The basic AMSS configuration consists of Server (s) as a host message-switching

computer, data server for storing and access data and agent workstation (s) for message

input.

The message switching system in major stations like Chennai or Kolkata configured as

below

AMSS Server with hot standby.

AMSS server console VDU and console printers

Data Base Server (s)

ADC/FIC Server

Communication Server

LTU Units

CCM Box

Router

Fast Ethernet Switch

Power Supply Unit


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MODEM (s)

Line Drivers

Windows-2000 Adv. Ser for Database Server

Windows-2000 professional for workstation

Different workstations (NODES)

Audio Visual Alarm (AVA)

Drop Printers

Report Printers

Workstation Printers.


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AMSS SERVER:-It receives messages, analyses routes, stores messages in duplicate

schedules and transmits messages. It gives health signals to SOLC and monitor its own sub-

systems for generating console messages. It also takes a snap shot of the System Status from

which the system can roll back in case of failure.

AMSS SWITCH SERVER H/W CONFIGURATION

AMSS is based on Intel PIII 1.13MHz microprocessor and the main system is fully

duplicated and each server consists of

Intel SDS2 Mother board integrated with 2 serial and 1 parallel port, 1GB memory, ultra2

SCSI controller, 52XIDE CD ROM , 2Ethernet NIC adapters, 1.44MB FDD,40GB disk

drive. DAT DRIVE 12GB, 24GB, Color monitor, key board and mouse.

64 port communication controller card

Disk switch

SOLC card

SCSI Active termination LVD.

AMSS SERVER HOT-STANDBY (HSB)

It receives the messages, preprocesses it and buffers received blocks with message

identification. It also gives health signals to SOLC. Hot standby on receiving signal from

SOLC, that online server has failed, it initiate recovery from the roll back point ledger by

ONL server in the last successful batch of operations. It then analyses the buffer of received

block to re-input into the system. The reception in HSB continues during all these activities.


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SYSTEM CONSOLE PRINTER

The system console is a VDU, which is used for booting, loading the OS, start up, date time

input and recovery. The console is basically a UNIX Terminal which can be used for any

program development activities also thro user friendly shell commands e.g. Editing source

program, Copying of programs, Diagnostics running etc.,

The system console printer attached with both the servers printers all the commands used by

the supervisor terminal and also logs the server activity, which helps the system administrator

to analyze the trouble.

DATABASE SERVER/ADC-FIC SERVER

The dual redundant servers supports the required data base support for the AMSS System for

various applications like ASBS, NOTAM office automation, HFRT, OPMET Data bank, YA

automation, ADC/FIC application etc., These servers are fully redundant and work in fail safe

mode. The database gets replicated in the Hot standby system based on events. Back end

software running on these servers supports the replication and transmission of messages

from/to the AMSS system and also supports the Workflow and automation application.

Supports the query and report request generated from the front-end GUI applications.

COMMUNICATION SERVER

This server supports various line protocols like X.25, HDLC, PPP, SLIP, TCP/IP etc.,

basically this server works as a gateway to remove stations connected in the X.25 and TCP/IP

cloud. All the messages received from the remote stations will be passed to the AMSS switch

through Ethernet connectivity and vice-versa. This server supports a minimum of four-eight

channels and both servers put together supports 8-16 channels.


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HW CONFIGURATION OF APP. FIC/ADC & COM SERVERS

These servers consist of

Intel SDS2 mother board with 2serial and one parallel port 1GB memory, integrated dual

ultra2 SCSI controller, dual channel RAID SCSI controller.

3 x 36GB Hot swappable disk drives

Color monitor, with key board and mouse

52 X IDE CD ROM

3.5,1.44MB FDD

X.25 Card ( for comm. Server)

NIC(Ethernet adapter)

Dual channel RAID SCSI controller( for App and FIC/ADC Servers)

LINE TERMINATION UNIT (LTU)

LTU rack with a capacity to support 64 channels is provided in view of the future expansion.

By adding additional line termination cards (LTU-B/C) and associate communication

multiplexers the system capacity can be enhanced. The software supplied supports up to 128lines. By simple updating the database, routing directory, the system capacity can be

enhanced to 128 channels.

There is one LTU for each line. LTU B/C interface supports two types of channels. LTUB

serves the function of converting Baudot code interface to RS232C interface. This unit also

provides line isolation, over voltage, current protection etc; LTU-C is basically RS232 to

RS232 with functions of line isolation TX signal selection (online systems TX signal only

allowed to the external line) and other protection facilities.


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MULTI-CHANNEL COMMUNICATION CONTROLLER MULTIPLEXER

( M-CCM)

The basic job of CP is to multiplex characters received from serial lines and informs the main

processor about reception of a fixed (256) number of characters or when a fixed string

(NNNN) has been detected.

The CP is provided with 64 Channel multiplexes (16/32/64CCM) cards in the On-line and

Hot-standby systems for supporting up to 64 asynchronous channels of different speeds from

50BPS to 9600BPS. Also reject printer for diagnostic report and report printer for activity log

is also connected to communication sub system. The dial up and COPB circuits are supported

through these communication controllers only. Since the communication controllers are

available in both on-line and hot-standby systems, the failure of any communication

multiplexes forces that switch over and hence does not hamper the availability of AMSS.

POWER SUPPLY UNITS

Dual power supply units for supply of (+/- 60V, +/-12V and +5V) is provided in LTU

rack. 60V is provided for remote lines, 12V for RS232C serial communication and 5V for

supply to LTU cards.

MODEM

MODEM is used as external or internal device to interface with low speed lines in the

AMSS system to communicate with the remote terminals. In ECIL system external

MODEM is used at very few stations. Modems are property of the service provider, in

this case MTNL.


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ROUTERS

In AMSS routers are used to connect the Delhi station to some of the neighboring stations

according to the TCP/IP protocol. The connectivity between these stations is provided by

MTNL. MTNL modems are installed at the end of the router which provides direct link to

the other stations. Stations like Jaipur, Allahabad, Lucknow are connected using router

connection.

At present AMSS uses 16 port routers manufactured by TECHROUTERS.

ETHERNET SWITCH

This intelligent device is used to form the LAN in the AMSS department. The sixteen

port switch from TYCO includes plug and play support. This allows the operation of the

switch without the need of configuration. The switch has a embedded software which

checks and stores the MAC address of the connected computer in its tables. However

these switches can be configured using hyperterminal using the RS-232 terminal attached

at the back of the switch.

LINE DRIVERS

Line drivers are used as a device to make long distance connectivity where the capacity of

a line fails to transfer the data from one terminal to another terminal. The line drivers are

fixed in between two points of a serial line RS232 (one at output end and other at input

end).

VOICE OVER INTERNET PROTOCOL (VOIP)

This device is used to transmit real time voice telephone conversations over the network in

TCP/IP encapsulated packets. Each VOIP processor has 8 ports for RJ-11 telephone lines

from the ordinary telephone.


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DIFFERENT WORKSTATIONS (NODES)

Supervisor, HFRT, Booking, NOTAM, MET, Briefing, Area etc are connected through

Ethernet switch or Hub.

All the WS are built around Intel P-III 700 MHz working under Windows 2000 &WIN-

XP operating system. Any WS can be enabled to work as AMSS supervisor, NOTAM

work station, ATC Workstation, MET Workstation etc. for example: ATC Workstations

are used to run required applications in various units like Workstation provides different

message templates for generating FPL, DEP, ARR, CNL, DLA, EST and CHG messages.

AUDIO VISUAL ALARM (AVA)

The Audio Visual Alarm (AVA) software monitors and displays the status of the entire

message switching system including its various allied sub-systems. The AVA displays

Switch status- MS1 and MS2

Device Status-Disks and Tapes

Power Supply status

Real time

Channel status

The AVA obtains all the status information from the ONLINE AMSS system through LAN

and displays them graphically. The graphical representation enables quicker and easier

interpretation of current status of the entire network.The status of all systems and sub-systems

are displayed in the form of rectangular blocks. The background color of a block indicates the

current status


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of the system/sub-system concerned. The date and time of failure are shown wherever they

are relevant.

In case of failure of message switches or disks which are critical, the software

Comes to the foreground if it had been minimized

Gives visual effect to the block concerned (in red color)

Generates alarm sound

The AVA software can also be run in any WS running Windows NT. The AVA terminal will

have special hardware to monitor LTU power status. If it is run on a WS other than AVA

terminal, then the status of all systems/sub-systems except LTU power status can be

monitored.

System Printer (SRP/SRJ) & DROP PRINTERS


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SRP- This printer is used for auto printing of various reports generated by the system.

SRJ- This printer is used for printing logging details of rejected messages by the system.

Also it logs the header summary of the messages transacted through LTU.

DROP printer (RS-232) used as a drop circuit through LTU. Printer is used for printing

messages to drop messages directly to an addressee as per address indicator for the drop

printer.

WORK STATION PRINTER

This printer is connected through the COM port of workstation and messages are

printed according to the address of the workstation. Messages can also be printed by

selecting the particular message and executing print command.

AMSS Software Configuration

AMSS switch servers:

Operating system: switch server works on UNIX operating system. The advantage of using

UNIX is the stability of the system. Since the two servers are the heart of the AMSS,

uninterrupted working is necessary in every case. Also the chance of virus attack is less as

compared to WINDOWS based system. UNIX version 5.05 is currently being used here.

Application: application for the switch servers are written in C language. The application

presently used is designed by ECIL and maintained by AAI.


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The application manages four files used in routing the messages to desired channel. These

being :

Ai8.data: maps address to route.

Gi8.data: maps group address to route.

Route.data: maps rote to logical address.

Line.data: maps logical to physical address.

Database server:

Operating server: database servers work on WINDOWS 2000.

Application: SQL 2000 is used for the database application. Databases contain tables

which hold the messages received from various inputs. A copy is retained for 30 days.

Workstations:

Operating server: workstations are loaded with windows XP OS.

Application: applications based on visual Care run on these stations.


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VHF

Very High frequency

Very high frequency (VHF) is theradio frequencyrange from 30MHzto 300MHz.

Propagation characteristics

VHFpropagationcharacteristics are ideal for short-distance terrestrial communication, with a

range generally somewhat farther than line-of-sight from the transmitter. Unlike high

frequencies (HF), theionospheredoes not usually reflect VHF radio and thus transmissionsare restricted to the local area. VHF is also less affected by atmospheric noise and

interference from electrical equipment than lower frequencies. Whilst it is more easily

blocked by land features than HF and lower frequencies, it is less affected by buildings and

other less substantial objects than UHF frequencies.

Universal Use

Certain subparts of the VHF band have the same use around the world. Some national uses

are detailed below.

108118 MHz: Air navigation beaconsVORandInstrument Landing Systemlocaliser. 118137 MHz:Airbandforair traffic control,AM, 121.5 MHz is emergency frequency

Modulation

Inelectronics, modulation is the process of varying one or more properties of a high-

frequency periodicwaveform, called thecarrier signal, with a modulating signal which

typically contains information to be transmitted.The three key parameters of a periodic

waveform are itsamplitude, itsphaseand itsfrequency. Any of these properties can be

modified in accordance with a low frequency signal to obtain the modulated signal. Typically

ahigh-frequencysinusoidwaveform is used ascarrier signal, but a square wave pulse train

may also be used.
http://en.wikipedia.org/wiki/Radio_frequencyhttp://en.wikipedia.org/wiki/Radio_frequencyhttp://en.wikipedia.org/wiki/Radio_frequencyhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Radio_propagationhttp://en.wikipedia.org/wiki/Radio_propagationhttp://en.wikipedia.org/wiki/Radio_propagationhttp://en.wikipedia.org/wiki/Ionospherehttp://en.wikipedia.org/wiki/Ionospherehttp://en.wikipedia.org/wiki/Ionospherehttp://en.wikipedia.org/wiki/VHF_omnidirectional_rangehttp://en.wikipedia.org/wiki/VHF_omnidirectional_rangehttp://en.wikipedia.org/wiki/VHF_omnidirectional_rangehttp://en.wikipedia.org/wiki/Instrument_Landing_Systemhttp://en.wikipedia.org/wiki/Instrument_Landing_Systemhttp://en.wikipedia.org/wiki/Instrument_Landing_Systemhttp://en.wikipedia.org/wiki/Airbandhttp://en.wikipedia.org/wiki/Airbandhttp://en.wikipedia.org/wiki/Airbandhttp://en.wikipedia.org/wiki/Air_traffic_controlhttp://en.wikipedia.org/wiki/Air_traffic_controlhttp://en.wikipedia.org/wiki/Air_traffic_controlhttp://en.wikipedia.org/wiki/Amplitude_modulationhttp://en.wikipedia.org/wiki/Amplitude_modulationhttp://en.wikipedia.org/wiki/Amplitude_modulationhttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Waveformhttp://en.wikipedia.org/wiki/Waveformhttp://en.wikipedia.org/wiki/Waveformhttp://en.wikipedia.org/wiki/Carrier_wavehttp://en.wikipedia.org/wiki/Carrier_wavehttp://en.wikipedia.org/wiki/Carrier_wavehttp://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/High-frequencyhttp://en.wikipedia.org/wiki/High-frequencyhttp://en.wikipedia.org/wiki/Sinusoidhttp://en.wikipedia.org/wiki/Sinusoidhttp://en.wikipedia.org/wiki/Sinusoidhttp://en.wikipedia.org/wiki/Carrier_wavehttp://en.wikipedia.org/wiki/Carrier_wavehttp://en.wikipedia.org/wiki/Carrier_wavehttp://en.wikipedia.org/wiki/Carrier_wavehttp://en.wikipedia.org/wiki/Sinusoidhttp://en.wikipedia.org/wiki/High-frequencyhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Carrier_wavehttp://en.wikipedia.org/wiki/Waveformhttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Amplitude_modulationhttp://en.wikipedia.org/wiki/Air_traffic_controlhttp://en.wikipedia.org/wiki/Airbandhttp://en.wikipedia.org/wiki/Instrument_Landing_Systemhttp://en.wikipedia.org/wiki/VHF_omnidirectional_rangehttp://en.wikipedia.org/wiki/Ionospherehttp://en.wikipedia.org/wiki/Radio_propagationhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Radio_frequency


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Need for Modulation

To reduce the antenna height and make it practical. To remove interference. Reduction of noise.

Superheterodyne Receiver

Inelectronics, a superheterodyne receiver (sometimes shortened to superhet) usesfrequency

mixingorheterodyningto convert a received signal to a fixedintermediate frequency, which

can be more conveniently processed than the original radio carrier frequency.

Design and principle of Operation

The principle of operation of the superheterodyne receiver depends on the use

ofheterodyningorfrequency mixing. The signal from the antenna is filtered sufficiently at

least to reject theimage frequencyand possibly amplified. Alocal oscillatorin the receiver

produces a sine wave whichmixeswith that signal, shifting it to a specificintermediate

frequency(IF), usually a lower frequency. The IF signal is itself filtered and amplified and

possibly processed in additional ways. The demodulator uses the IF signal rather than the

original radio frequency to recreate a copy of the original modulation (such as audio).
http://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Heterodyninghttp://en.wikipedia.org/wiki/Heterodyninghttp://en.wikipedia.org/wiki/Heterodyninghttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Heterodyninghttp://en.wikipedia.org/wiki/Heterodyninghttp://en.wikipedia.org/wiki/Heterodyninghttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Image_frequencyhttp://en.wikipedia.org/wiki/Image_frequencyhttp://en.wikipedia.org/wiki/Image_frequencyhttp://en.wikipedia.org/wiki/Local_oscillatorhttp://en.wikipedia.org/wiki/Local_oscillatorhttp://en.wikipedia.org/wiki/Local_oscillatorhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Local_oscillatorhttp://en.wikipedia.org/wiki/Image_frequencyhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Heterodyninghttp://en.wikipedia.org/wiki/Intermediate_frequencyhttp://en.wikipedia.org/wiki/Heterodyninghttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Frequency_mixerhttp://en.wikipedia.org/wiki/Electronics


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Frequency band

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 MHz300 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

TYPES OF ANTENNA IN VHF COMMUNICATION

1) DIPOLE ANTENNA

A dipole antenna is a radio antenna that can be made of a simple wire, with a center-fed

driven element. It consists of two metal conductors of rod or wire, oriented parallel and

collinear with each other (in line with each other), with a small space between them. The

radio frequency voltage is applied to the antenna at the center, between the two conductors.


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2) FOLDED DIPOLE

Another common place one can see dipoles is as antennas for the FM band - these are folded

dipoles. The tips of the antenna are folded back until they almost meet at the feedpoint, such

that the antenna comprises one entire wavelength. This arrangement has a greater bandwidth

than a standard half-wave dipole. If the conductor has a constant radius and cross-section, at

resonance the input impedance is four times that of a half-wave dipole.


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RADIATION PATTERN (OMNIDIRECTIONAL)

In the field of antenna design the term radiation pattern most commonly refers to the

directional (angular) dependence of the strength of the radio waves from the antenna or other

source.

Since electromagnetic radiation is dipole radiation, it is not possible to build an antenna that

radiates equally in all directions, although such a hypothetical isotropic antenna is used as a

reference to calculate antenna gain. The simplest antennas, monopole and dipole antennas,

consist of one or two straight metal rods along a common axis. These axially symmetric

antennas have radiation patterns with a similar symmetry, calledomnidirectionalpatterns;

they radiate equal power in all directions perpendicular to the antenna, with the power

varying only with the angle to the axis, dropping off to zero on the antenna's axis. This

illustrates the general principle that if the shape of an antenna is symmetrical, its radiation

pattern will have the same symmetry.
http://en.wikipedia.org/wiki/Omnidirectional_antennahttp://en.wikipedia.org/wiki/Omnidirectional_antennahttp://en.wikipedia.org/wiki/Omnidirectional_antennahttp://en.wikipedia.org/wiki/Omnidirectional_antenna


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3) YAGI UDA ANTENNA

A Yagi-Uda array, commonly known simply as a Yagi antenna, is a directional antenna

consisting of a driven element (typically a dipole or folded dipole) and additional parasitic

elements (usually a so-called reflectorand one or more directors). The reflector element is

slightly longer (typically 5% longer) than the driven dipole, whereas the so-called directors

are a little bit shorter. This design achieves a very substantial increase in the antenna's

directionality and gain compared to a simple dipole.

Highly directional antennas such as the Yagi-Uda are commonly referred to as "beam

antennas" due to their high gain. However the Yagi-Uda design only achieves this high gain

over a rather narrow bandwidth, making it more useful for various communications bands

(including amateur radio) but less suitable for traditional radio and television broadcast

bands.

Stacking Yagi Antennas:

The capture area of an antenna - usually known to professionals as its effective apperture-

is roughly defined as the area covered by a planar or aperture array with the same gain and

beamwidth characteristics.


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For example, if we built a giant horn antenna with the same gain and beamwidth as the yagi

that we're viewing head-on in the diagram below, the front aperture of the horn would be the

same as the effective aperture of the yagi.

The effective aperture of a yagi is roughly elliptical, with its longer axis along the length of

the elements. Note that the effective aperture extends symmetrically above and below the

plane of the elements, and also extends symmetrically out beyond the physical length of the

elements.

More Capture Area = More Gain

The bigger the capture area of any antenna, the higher is its gain. A longer yagi - if it's well

designed - will have more gain and a larger capture area than a shorter yagi; roughly, the gain

and capture area of a yagi are both proportional to the boom length (in wavelengths).

RADAR

Introduction

Radar is basically means of gathering information about distant objects, or targets (aircraft

etc), by sending electromagnetic waves (generally the UHF or Microwaves) at them and

analyzing the echoes. It was evolved during the World War II. At, first, it was used as an all

weather method of detecting approaching aircraft, and later for many other purposes. The

word itself is an acronym from the words RADIO DETECTION AND RANGING.


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Principle of RADAR

The electronic principle on which radar operates is very similar to the principle of sound-

wave reflection. If you shout in the direction of a sound-reflecting object (like a rocky canyon

or cave), you will hear an echo. If you know the speed of sound in air, you can then estimate

the distance and general direction of the object. The time required for an echo to return can be

roughly converted to distance if the speed of sound is known. Radar uses electromagnetic

energy pulses in much the same way. The radio-frequency (RF) energy is transmitted to and

reflected from the reflecting object. A small portion of the reflected energy returns to the

radar set. This returned energy is called an ECHO, just as it is in sound terminology. Radar

sets use the echo to determine the direction and distance of the reflecting object.

Radar consists of transmitter and receiver, each connected to a directional power through the

antenna. The receiver collects as much energy as possible from the echoes reflected to it from

the target and then processes and displays the image in a suitable way. Now a days the

receiving and transmitting are same which is accomplished by the use of duplexer and time

division multiplexing arrangement, since the radio energy is very often sent out in the form of

pulses. The function of duplexer is to isolate the transmitter and receiver during reception, to

protect the receiver from high power transmitter, to help use a single transmitter/receiver

antenna.


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A master timer controls the pulse repetition frequency (PRF) or pulse repetition rate (PRR).

A highly directional parabolic antenna at the target transmits these pulses, which can reflect

(echo) some of the energy back to the same antenna. This antenna has been switched from a

transmit mode to receive mode by a duplexer. This reflected energy is received, and the

measurements are made, to determine the distance of the target.

Band DesignationsNominal Frequency Range

(GHz)Used In

UHF 0.3 - 1 Data communication

LBand 1.02.0 ARSR

SBand 2.04.0 ASR

CBand 4.08.0 Weather

XBand 8.012.5 ASMGCS

KuBand 12.518.0


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Factors affecting Range of Radar

Transmitter power: Range of the radar is directly proportional to the power of the pulse

transmitted by the transmitter.

Frequency:

range of the radar

RADAR DISPLAYS

The output of a radar receiver may be displayed in any of a number of ways, the following

three being the most common: deflection modulation of a cathode-ray-tube screen as in A-

scope, intensity modulation of a CRT as in plan position indicator (PPI) or direct feeding to

computer.

A-Scope: This is the most popular of the deflection modulation type display systems, which

indicates the range of the target. Its operation is similar to that of an ordinary CRO. A beam is

made to scan the CRT screen horizontally by applying a linear saw tooth voltage to the

horizontal deflection plates in synchronism with the transmitted pulses. The demodulated

echo signal from the receiver is applied to the vertical deflection plates so as to cause vertical

deflection from the horizontal line. In absence of any echo signal, the display is simply is a

horizontal line.


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IMPORTANT RADARS

Continuous Wave RADAR

It is a simple Doppler radar, transmitter of which generates a continuous sine wave of

frequency fo which is radiated by the antenna. This radaruses the Doppler Effect to detect

the frequency change caused by a moving target and displays this as the relative velocity. If a

target is in motion with a velocity (Vr) relative to the radar, the received signal will be shifted

in the frequency from the transmitted frequency fo by an amount fd. The plus sign denotes

an approaching target and minus sign denotes a receding target. The received echo signal (fo

d ) enters the radar via the antenna and is mixed in a detector mixer with a portion of the

transmitter signal fo to produce the Doppler frequency fd. The purpose of using a beat

frequency amplifier is to eliminate echo from stationary targets and to amplify the Doppler

echo signal to level where it can operate an indicating device as a frequency meter. However

practical application of the CW radar is limited by the fact that several targets at given

bearing tend to cause confusion. Also, it is not capable of indicating the range of the target


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and can show only its velocity. The other improved system of radar that uses this method is

Moving Target Indicator (MTI) radar.

MOVING TARGET INDICATOR (MTI) RADAR

This radar also uses the principle of Doppler effect. Many a times it is not possible to

distinguish a moving target in the presence of static or permanent echoes of comparable

appearance on the radar screen.

As we know there is lot clutter in a PPI display, there is a lot of clutter due to these stationary

target echoes. Also it is quite possible that a moving target has a range and bearing such that

the echo from the moving target gets superimposed on the ground clutter. Such a condition

can exist in mountainous region or in close vicinity of modern cities cluttered with tall

buildings. Another example could be when a moving airplane seeks o hide behind other

airplanes as in wartime, when deliberately, pilot less airplanes at lower height provide cover

for bombers racing above. This is done so that radar cannot pick the bombers and to avoid

antiaircraft action.

Principle: When it is desired to remove the clutter due to stationary targets, MTI radar is

employed. The basic principle of MTI radar is to compare a set of received echoes with those

received during the previous sweep and canceling out those whose phase has remained

unchanged. Moving targets will give change of phase and are not cancelled. Thus clutter due

to stationary targets both man-made and natural are removed from the displays and this

allows easier detection of moving targets (whose echoes are normally 100 times smaller than

those of nearby stationary targets.


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CONCLUSION :

Under the supervision of Mr. S.K Tomar, training at AIRPORTS AUTHORITY OF INDIA

has been completed successfully.

During the course of training I learnt about various navigational-aids and studied Instrument

Landing System (ILS) in detail.


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APPENDIX

ILS categories

There are three categories of ILS which support similarly named categories of operation.

Information below is based on ICAO; certain states may have filed differences.

Category I (CAT I)A precision instrument approach and landing with a decisionheight not lower than 200 feet (61 m) above touchdown zone elevation and with either

a visibility not less than 800 meters (2,600 ft) or arunway visual rangenot less than

550 meters (1,800 ft).

Category II (CAT II)A precision instrument approach and landing with a decisionheight lower than 200 feet (61 m) above touchdown zone elevation but not lower than

100 feet (30 m), and a runway visual range not less than 300 meters (980 ft) for

aircraftapproach categoryA, B, C and not less than 350 meters (1,150 ft) for aircraft

approach category D.

Category III (CAT III) is subdivided into three sections:

o Category III AA precision instrument approach and landing with: a) a decision height lower than 100 feet (30 m) above touchdown zone

elevation, or no decision height (alert height); and

b) a runway visual range not less than 200 meters (660 ft).o Category III BA precision instrument approach and landing with:

a) a decision height lower than 50 feet (15 m) above touchdown zoneelevation, or no decision height (alert height); and

b) a runway visual range less than 200 meters (660 ft) but not less than75 meters (246 ft). Autopilot is used until taxi-speed. In the United

States, FAA criteria for CAT III B runway visual range allows

readings as low as 150 ft (46 m).

o Category III CA precision instrument approach and landing with nodecision height and no runway visual range limitations. This category is not

yet in operation anywhere in the world, as it requires guidance to taxi in zero
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visibility as well. "Category III C" is not mentioned in EU-OPS. Category III

B is currently the best available system.


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BIBLIOGRAPHY :

www.wikipedia.org www.aai.aero.in References from supervisors
http://www.wikipedia.org/http://www.wikipedia.org/http://www.aai.aero.in/http://www.aai.aero.in/http://www.aai.aero.in/http://www.wikipedia.org/

Documents

Training Report Abhishek Gupta