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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_approach8/3/2019 Training Report Abhishek Gupta
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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_frequency8/3/2019 Training Report Abhishek Gupta
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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).
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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.
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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
http://en.wikipedia.org/wiki/Runway_visual_rangehttp://en.wikipedia.org/wiki/Runway_visual_rangehttp://en.wikipedia.org/wiki/Runway_visual_rangehttp://en.wikipedia.org/wiki/Aircraft_approach_categoryhttp://en.wikipedia.org/wiki/Aircraft_approach_categoryhttp://en.wikipedia.org/wiki/Aircraft_approach_categoryhttp://en.wikipedia.org/wiki/Aircraft_approach_categoryhttp://en.wikipedia.org/wiki/Runway_visual_range8/3/2019 Training Report Abhishek Gupta
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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/Top Related