CONTENT

1. AN INTRODUCTION TO C.A.T.C.

2. VHF COMMUNICATION SYSTEMS

3. NAVIGATIONAL AIDS

4. AMSS(Automatic Switching System)

5. SECURITY EQUIPMENTS

6. RADAR SIMULATOR

AN INTRODUCTION TO CIVIL AVIATION TRAINING COLLEGEInternational aviation is undergoing the most dramatic changes in its history. The National Airport Authority; an agency of government of India is responsible for planning, development and management of Air Traffic Control, Communication, Navigation and Surveillance Service over Indian air space. It has to provide its Engineers and Air Traffic Controller with initial, refresher and specialized training designed to equip them with skills and knowledge to meet the organizational objectives.CATC has been created, since 1948, to meet that objective. The theoretical and practical content of its training program, its learning methodology, and its learning environment have all been planned to provide training to officers from within and outside NAA to enable them to discharge their duties at field station in a professional manner so as to ensure efficient, safe regular Air Traffic over Indian air space.CATC is situated in a superb area, called BAMRAULI at the distance of 10 km west from Allahabad.This organization is governed by the norms of International Civil Aviation Organization.

FUNCTIONS OF THE AIRPORTS AUTHORITY OFINDIA (AAI)1. To manage the aerodromes, the civil enclaves and the aeronautical communication station efficiently.2. To provide air traffic service at any aerodromes and civil enclaves.3. Without prejudice to the generality of the provisions contained in subsection (1) & (2), the authority may; Plan, develop, construct and maintain runway, taxiway, aprons and terminal and ancillary building at the aerodromes. Plan, procured, install and maintain navigational aids, aerodromes and at such location as may be considered necessary for safe navigation and operation of aircraft. Provide air safety service and rescue facilities in coordination with other agencies. Establish school or institute or training of its officers and employees in regard to any matter connected with the purpose of this Act. Construct residential building for its employee. Establish warehouse and cargo complexes at the aerodromes and civil enclaves. Establish and manage heliports. Such transport facility as are, the opinion of the authority necessary to the passengers traveling by air.

4. In the discharge of its function under this section the authority shall have due regard to the development of air transport service and to the efficiency, economy and safety of such service. 5.Nothing contained in this shall be constructed as:(a) Authorizing the disregard by the authority of any law for the time being in force ; or(b) Authorizing any person to institute any proceeding in respect of duty or liability to which the authority or its officers or other employees would not otherwise, be subject.

ORGANIZATION CHART

Very High Frequency(VHF)Communication System

1. Communication is the process of sending, receiving and processing of information by electric means. Radio communication employs the electromagnetic waves for carrying information from one place to another.2. The electromagnetic waves whose frequency is within the band 30 MHZ to 300MHZ are defined as Very High Frequency (VHF) radio waves. VHF frequencies are not affected by atmospheric noise. The main characteristics of the VHF communication system are as follow:-

VHF Transmitter A transmitter uses an oscillator to produce the desired radio frequency current. Crystal controlled oscillators are normally employed to provide better frequency stability. Thinner the crystal, higher will be the operating frequency. At present the limit of fundamental mode of operation of a crystal is at 20 MHZ. multiplier circuits. However, employing crystal overtone oscillators can reduce the number of such circuits. In a VHF Amplitude Modulation (AM) transmitter low-level modulation is normally employed. VHF Receiver VHF receiver must be capable of receiving weak signal of the order of 2 mV. Intermediate Frequency (IF) of 10.7 MHZ is employed to provide sufficient image rejection. In practice bandwidth of about 15 KHz to KHz are usually required. Good Automatic Gain Control (AGC) performance is essential for AM receiver used in mobile system since the input signal may vary by 100dB or so depending on distance. Radiation and Propagation of VHF Dipole antenna is used to radiate VHF radio signals. A folded dipole has following advantages:a) Higher input impedance.b) Greater bandwidth.

Space Wave Propagation The VHF radio waves radiated from an antenna propagate in the form of space waves travel in straight lines and hence they depend on Line of Sight (LOS) conditions. Because of this limitation of space waves, their range of propagation is limited by the curvature of the earth.

Factors affecting the design of VHF systemThere are a number of factor that affect the design of VHF communication system; some of these factors are:-a) Noise: External noise has no effect on the VHF signal. To receive weak VHF signals, the sensitivity of the receiver should be high, therefore RF amplification is required. Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is normally employed in the construction of Oscillator and Amplifier circuits.b) Skin Effect: The effective resistance offered by a conductor to Radio frequency (RF) current is considerably more than the ohmic resistance measured using direct current. This is because of a phenomenon known as the skin effect.c) Losses: Losses can occur in three ways in communication system. Radiation Losses Propagation Losses Dielectric Lossesd) Proximity Effect: When two or more adjacent conductors carrying current, as it happens in a coil, current distribution in any one conductor is affected by the magnetic flux produced by the adjacent conductor as well as the flux produced by the current in the conductor itself. This effect is termed as proximity effect.

Use of VHF in Civil Aviation: VHF communication is suitable for mobile application. Hence, civil Aviation employs VHF communication between aircraft and ground control station, for exchange of message related to air traffic service. VHF also finds application in the radio navigational aids. The frequency band 108MHz -137MHz has been allocated by the International Telecommunication Union (ITU), in consultation with the International Civil Aviation Organization (ICAO) for use in civil aviation.The two main application of VHF in civil aviation are:a) Aeronautical Radio Navigation service(ARNS)b) Aeronautical Mobile Service (AMS) Aeronautical Radio Navigation Service (ARNS) ARNS provides the route navigational facilities and instrument approach facilities to the aircraft. The VHF frequency band 108 to 117.975MHz has been allocated for this purpose. Aeronautical Mobile Service (AMS) AMS which is provided in the form of Radio Telephony (RT) is the mean by which pilot and ground Air Traffic Control (ATC) personnel communicate with each other. The VHF frequency band 117.137MHz has been allocated for this purpose.

Air Ground VHF Communication System Characteristics System Characteristics: The characteristics of the Air-Ground VHF communication system used in the instrument AMS have to be conformity with the following specification:a) RF emission have to be continuous wave (CW) amplitude modulated (AM) carriers, mode A3E.b) Spurious emissions have to be kept at the lowest level.c) The radio frequencies used have to be kept at lowest level.d) The polarization of emission has to be vertical.e) Single simplex operation has to be used.

Ground Installation Transmitting Function The VHF transmitter installed on the ground for the AMS should have the following specifications:-a) Frequency Stability: The radio frequency of operation should not vary more than 0.002% from the assigned frequency for 25 KHz channel separation. For 50 KHz or more channel separation, the variation should not exceed 0.005%.b) Power: The effective radiation power should be such that it produces field strength of at least 75V per meter within the operational coverage of the facility, on the basis of space wave propagation.c) Modulation: A peak modulation factor of at least 0.85 should be achieved. Mean should be provided to maintain the average modulation factor at the highest practical value without over modulation. Ground Installation Receiving Function:-a) Sensitivity: The receiver should be capable of producing an audio output with wanted/unwanted ratio of 15dB when 50% amplitude modulation (A3E) ratio signal having field strength of 20v per meter or more intercept the receiving aerial.

b) Effective Acceptance Bandwidth: The receiver should provide an adequate and intelligible audio output when the radio in (a) above has a carrier frequency within 0.005% of the assigned frequency. c) Adjacent Channel Rejection: The receiving system should ensure an effective rejection of 60dB or more at the next assignable frequency channel.VHF Transmitter specification:- The DT100 comprises independent modules, each of them dedicated to a specific function. The equipment can be provided in different configurations according to the type of fitted modules. The following block diagram highlights the modularity of DT100BLOCK DIAGRAM OF DT100

Modular Architecture allows for:a) Easy reconfiguration for transaction to any VDL modes application.b) Availability of a wide range of interface options toward external transport networks.c) Low MTTR, and easy on-field maintenance, carried out by modules direct replacing.

A set of main modules composes the transmitter (radio section). These modules are:a) Transmitter module(TX)b) Base band Module (BB)c) Power Supply Unit (PSU) The operation and maintenance and local management function are carried out by means of specific management modules, Which are available in different configurations: i. IMC/MSIC cardsii. Control Panel (standard and enhanced HMI) The interface to external voice switching device (for analogue Operating modes), or data link external network, modems or Station controllers (for VDL modes), are carried out by means Of specific line interfacing cards i.e. Line Barrier card (e.g. ALB-S, ALB-M).

. Analogue Line Barrier (ALB): They are used in AM-DSB and AM- DATA mode, when the equipment must process analogue speech Communication and analogue interfacing with external Voice Communication Switching Systems or external ACARS modem.I. The ALB-S (ALB system The ALB-M (ALB minimal) is a basic Line Barrier card. It provides speech conversion from analogue to PCM format for both TX and RX. The local/remote switching is operated by ALB-M on IMC/MSIC command, after the local mode selection operated through HMI relevant command.II. ) is an extended and more flexible Line Barrier card. It is more complex than ALB-M, and features a microprocessor operating on the RCB bus, to control and manage local board activity and interfacing with the O&M functions within IMC/MSIC. ALB-S can manage two separate audio and signaling lines toward the external, supporting redundancy.. Digital Line Barrier (DLB): It may be used either in AM-DSB, AM-DATA, or VDL modes, when the equipment must be interfaced in digital format with external controllers or transport network. Digital Line Barrier card may cover a wide range of connectivity solution when used in any of VDL modes. The ratio section is arranged onto a RF- motherboard allowing for the distribution and exchange of signal, busses and operating supplies, while the management and line-barrier cards are arranged onto the cards-motherboard (with the exception of control panel that is fitted on the front side). The connection between motherboards is given by the interconnection board suitable to route toward radio-section the relevant signals and busses (e.g. RCB).

VHF Receiver specifications:- The DR100 comprises independent modules, each of them accomplishing a different and specific function. The equipment can be provided in different configurations according to the type of fitted modules.

NAVIGATIONAL AIDS Navigation is the art of determining the position of an aircraft over earths surface and guiding its movement in the air, from one place to another. Equipment, system, devices, charts, or methods intended to assist in the navigation of an aircraft are called Navigation Aids. . Civil Aviation employees the following four types of navigation Aids. . Very High Frequency Range (VOR) . Non Directional Beacon (NDB) . Instrument Landing System (ILS) . Distance Measuring Equipment (DME) The above Navigational Aids are also called Radio Navigational Aids because They provide guidance using Radio Waves.VHF OMNI RANGE It means a very high frequency Omni directional radio range. It is basically a transmitter. It operates in the VHF band of 108 to 118 MHz. When it operates in the frequency range 108-112 MHz then it is used for flying aircraft from one place to another and called an route VOR. It provides azimuth information to the flying aircraft from particular VOR station with respect to the magnetic north. It works on the principal of phase comparison.Purpose of VOR and Uses: The main purpose of the VOR is to provide the navigational signals for an aircraft receiver, which allow the pilot to determine the bearing of the a aircraft to a VOR facility. It enables the air traffic controller in the area controller radar and air surveillance for identifying the aircrafts in their scope easily. They can monitor aircrafts are following the signals correctly or not. VOR located outside the airfields on the extended centre line of the runway would be useful for the aircrafts making a straights VOR approach. With the help of the autopilot aircraft can be guided to approach airport for the landing. VOR located Enroute would be useful for air traffic to maintain their predetermined routes and are also used at reporting points VOR located at riddle distance of about 40 miles in different directions along international airports can be used as holding VOR for regulating the aircrafts for their landing for quickest time. They would be immense help to the aircrafts for holding overhead and also to the ATCO. For handling the traffic conveniently.Principle of operation Aircrafts determines its bearing by comparing a face of reference 30Hz and variables 30Hz signals. Reference 30Hz signals has the same face at all the 360 pts around VOR whereas face of 30Hz signals changes at the rate of 1 for one degree deviation of azimuth angle. The reference 30Hz signal and variable 30Hz signal are in the same phase in the direction of magnetic north in fact this direction taken as 0 for VOR and other azimuth angles are measured in clockwise direction in figures. The VHF radio range transmitter radiates to patterns distinguishable by different modulations, one of which is omni-directional And carries the modulation of reference signals.

Magnetic north

The 30Hz signals cannot be directly radiated into space. These signals modulate carrier frequency 113 MHz in a specific manner and aircraft receiver processes the signal and derived the desired information beside station identification and voice signals are also radiated. The signals radiated from the VOR are as follows Reference 30Hz Variable 30Hz Station Identification Voice signal The above mentioned signals modulate the carrier and following RF signals are radiated from the antenna systems. Reference carrier Variable carriersReference Carrier Reference 30Hz sinusoidal signal frequency modulates 9960Hz signal. This 996Hz signal will be referred as sub carrier VOR system. This sub carrier amplitude modulates the carrier.Station Identification and Voice Signal Every VOR station radiates on its identification. This signal indicates pilot to VOR to which he has tuned. The station code is a combination of English alphabets, these alphabets are Morse coded and in these the code audio frequency of 1020Hz is generated. This coded audio signal amplitude modulates. Audio signal corresponding to voice meant for communicating with aircrafts also modulates the carrier. The carrier modulates by all the above signals is called reference carrier And is fed to aural systems, which has Omni radiation pattern.

Variable carrier Variable 30Hz sinusoidal signal modulates the carrier and the variable carrier is obtained. An earlier version of VOR does it by rotating fed with pure carrier at the rate of 30rev/sec. The radiation pattern is dipole is shown in figure.

RADIATION PATTERN OF A DIPOLE

And the dipole is rotated, so this pattern also rotates. The plus radiation adds the Omni reference carrier and minus radiation subtracts. The resultants radiation is a Limacine as shown in fig.

Audio phase relationship of reference of 30Hz and variable 30Hz at different direction is shown in fig.

Types of VOR: there are two types of VOR, namely Conventional VOR (C-VOR) Doppler VOR(D-VOR)

Even though both the serve the same purpose as far as the aircrafts are concerned, the selection of C-VOR and D-VOR depends upon various sides conditions and airfields. D-VOR is more accurate than C-VOR but is complex and costlier than C-VOR. In C-VOR only one antenna is used but in D-0VOR normally 49 or 51 antenna are used. In the D-VOR systems the reference signals is transmitted from the from a central aerial called reference antenna and it is amplitude modulated. The variable signal is transmitted from a system of 50 or 48 aerials encircling the central and it is frequency modulated. These aerials are called sideband antennas.

NON-DIRECTIONAL BEACONIt is simple amplitude modulated low power transmitter. It operates in the frequency range 190 KHz to 1750 KHz. For Indian NDB it is 190 KHz to 450KHz. NDB provides relative bearing. Relative bearing may be defend as an angular relationship between nose of aircraft and direction of NDB station taken clockwise.Power of Transmitter: High power (up to 10Kw) Medium power(250-500w) Low power (10-50w)Service provided by NDB: Homing Holding Enroute Position fixing

1. Homing : when the relative bearing is zero then direction of nose of the is towards NDB station, this is called homing2. Holding: when the relative bearing is 90 and the aircrafts maintains this position then the aircraft revolves in a circular path around the NDB station, this is called holding.3. Enroute: facility provides the route between the different stations. Which are situated at a long distance.4. Position fixing: aircrafts is able to establish angular relationship between at least two or more NDB station mapping on its real map, this is called position fixing.BLOCK DIAGRAM OF NDB TRANSMITER:

NDB navigation actually consists of two parts, the Automatic Direction, Finding (or ADF) equipment on the aircrafts that detects and NDBs signals, and the NDB transmitter itself. The ADF can also locate transmitters in the standards AM medium wave broadcast band (530KHz to 1700KHz at 10KHz increments in the America, 531KHz to 1602KHz at 9KHz increments in the rest world. ADF equipment determines the direction to the NDB station relative to the aircrafts. They may be displayed on a relative bearing indicator (RBI). This display look like a campus card with a needle superimposed, except that the card is order to the track towards and NDB with no wind the aircraft is flown so that the needle points to the zero position, the aircraft will then fly directly to the NDB. Similarly aircraft will track directly away from the NDB if the needle is maintained on the 180 degree mark. With a crosswind the needle must be maintained to the left or right of the zero or 180 position by an amount corresponding to drift due to the crosswind.

INSTRUMENT LANDING SYSTEM (ILS)Instrument landing system (ILS) is the international standard for approach and landing guidance. ILS was adopted by International Civil Aviation Organization (ICAO) in 1947. The instrument landing system (ILS) is a grounded based instrument approach system which provides precise guidance to an aircraft approaching a runway, using a combination of radio signals and, in many cases high intensity lightening arrays to enable a safe landing during instrument visibility, fog, rain. or blowing snow.Components of ILSTo provide correct approach path information to the pilot, three different signals are required to the transmitted. The first signal gives the information to the pilot indicating the aircraft position relative to the central line of the runway.The second signal gives the info indicting the aircraft position relative to the required signal of the descent, where as the third signal provide distance info from some specified points. The three parameters which are essential for a safe landing are azimuth approach guidance, elevation approach guidance and range from the touchdown point. These are provided to the pilot by the component of the ILS namely localizer, glide path and maker beacons respectively. At some airports, the maker beacons are replaced distance measuring (DME). This info summarized in the following table ILS parameterILS component

Azimuth approach guidanceProvided by localizer

Elevation approach guidanceProvided by glide path

Fixed distance from thresholdProvided by marker becomes

Range from touchdown pointsProvided by DME

Principle of operation ; an ILS consists of two independents sub systems, one providing lateral guidance (localizer), the other vertical guidance(Glide slope or path) to aircraft approaching a runway.

A localizer (LOC or LLZ in Europe) antenna array is normally located beyond the departure end of the runway and generally consists of several [airs of directional antennas. Two signals are transmitted on a carrier frequency between 108.10MHz and 111.975MHz. one is modulated at 90Hz , the other at 150Hz and these are transmitted from separate but co located antennas each antennas transmits of freely, narrow beam, one slightly to the left of the runway central line, to other to the right. The localizer receiver on the aircrafts measures the difference in the depth of modulation (DDM) of the 90Hz and the 150Hz signals. For the localizer, the depth of modulation for each of the modulating frequencies 20%. The difference between the two signals varies depending on the position s of the approaching of the aircrafts from the central line. If there is a predominance of either of 90 or 150Hz modulation. The aircrafts is of the central line. In the cockpit, the needle of the horizontal situation indicator or HIS (the instrument part of the ILS) , will show that the aircrafts needs to the fly left or right to correct the positional error to the fly down the centre of the runway. If the DDM is 0 the receiver aerial and therefore, the aircraft is on the centre line of the localizer coinciding with the physical runway centre line. A glide slope or glide path GP antenna array is sited to one side of the runway touchdown zone. The GP signal is transmitted on a carrier between 329.15 and 335 MHz using a technique similar to that of the localizer. The centre line of the glide slope signal is arranged to define a glide slope of approximately three above the horizon. Localizer and glide slope carrier frequencies are paired so that only selection is required to tune both receivers These signals are displayed on an instrument in the cockpit. The pilot controls the aircraft so that the indications on the instrument remain centre on the display. This ensures the aircraft is following the ILS centre line. Some aircraft posses the ability to route signals into the auto pilot, which allows the app[roach to be flown automatically by the autopilot. In addition to the previously mentioned navigational, the localizer provides for ILS facility identification by periodically transmitted are 1020Hz morse code identification.Maker beacons:Almost installations maker beacons operating at a carrier frequency of 75MHz are provided. When the transmutation from a marker beacon is received it activates indicator on the pilot instrument panel and the modulating two of the beacon is audible to the pilot. The correct height the aircraft should be at when the signal is received in an aircraft is promulgated.

Outer marker:The outer marker should be located 7.2Km (3.9NM) from the threshold except the , their these distance from practicable , the outer marker may be operated between 6.5 and 11.1 KM (3.5 and 6NM) from the threshold the modulation is repeated morse style dashes of a 400Hz tuned. The cockpit indicator is a blue lamp that fleshes in unison with the received of audio code. The purpose of this beacon is to provide height, distance and equipment functioning checks to aircrafts intermediate and final approach. In the US, an NDB is often combined with the outer marker beacon in the ILS approach (called a lector outer marker or LOM ) in Canada low powered have replaced marker beacons entirely. Middle marker:The middle marker ,when installed, shall be located so as to indicate low visibility conditions the immense of arrival at the runway threshold this is typically position of an aircraft on the ILS at it reach category 11 minima. The modulation is Morse D- style dots at 3000Hz. The cockpit indicator is a white lamp that flashes in unison with the received audio code.

DISTANCE MEASURING EQUIPMENTAs the name indicates is electronic equipment used to measure slant range distance between aircraft and a ground. TX- DME operates in UHF range between 960MHz to 1215MHz. it is a transponder based radio navigation technology generally co located at VORs. DME transponder transmits on 962 MHz to 115MHz and receiver on 962 MHz to 1213MHz. Aircrafts use DME to determine their distance from a land based transponder by sending to pulses with a random time interval between them. The transponder echoes the pulses. The DME receivers then search for two pulses with correct time interval and measure the delay between the pulses transmission and the pulses receptionApplication of DME: The DME is used for A navigational aid in conjunction with the VOR. A component of ILS where DME is also alternate to marker beacons. A component of microwave landing system (MLS) Expedite the RADAR identification of aircraft.Principle of operation: The operating principle of DME system is based on the radar principle e.g. the time required for a radio pulse signal to travel to a given point and return. In fact it is secondary radar. In secondary radar system the target active participation is necessary for its detection as against primary radar where the target role is passive. Secondary radar system basically consists of two principle component namely the interrogator which is ground based and the transponder which is carried on the target. Each of these components of a set of one pulse transmitted and one corresponding transponder on a target will initiate reply from that transponder. These replies are then collected by the interrogator about the targets.

BASIC BLOCK DIAGRAM OF DME SYSTEM

DME is secondary radar with the location of the transponder and interrogator reversed. Fig shows the elements of the DME systems. Referring to fig the air bond transmitter repeatedly initiate 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. These reply pulses are collected by the airborne receivers. Timing circuits automatically measure the round trip travel time or interval between interrogation and reply pulses, and concern this time into electrical signal, which operates the distance indicator.

SECURITY EQUIPMENTS

Security equipment are used for security purpose at the airports. Security equipment are used to check the luggage and passengers at the airport so that no one can bring illegal and harmful things such as metallic weapons and explosive materials inside the airport region. The various types of security equipment used by the Airport Authority of India (AAI) are as follows: Hand Held Metal Detector (HHMD) Door Frame Metal Detector (DFMD)/Walk Through Metal Detector(WTMD) X-Ray Baggage Inspection System (X-BIS) Hand Held Metal Detector: Old metal detectors worked on energy absorption principal used two coils as search coils; these were forming two loops of a blocking oscillator. When any person carrying a metallic object or weapons stepped through the door carrying coils, some energy was absorbed and the equilibrium of the blocking oscillator got disrupted. This change was converted into audio and visual indication. Size and weight of the metallic object was determined by proper sensitivity settings. The hand held metal detectors used the same technique. These types of metal detectors carried various shortcomings and they have been superseded by new generation multi zone equipments.

RADARIntroduction RADAR is basically a means of gathering information about distant objects called targets by sending electromagnetic waves at them and analyzing the returns call the ;echoes. It was evolved during the Second World War independently and mover or less simultaneously by USA, Great Britain, Germany and the France. The work RADAR is an acronym coined by the US Navy from the works Radio Detection and Ranging.Basic PrinciplesRadar is a radio device capable of providing information on rage and bearing, in azimuth an elevation of objects. In principal, the radar can be compared with a beam of light. If a ray of light shines on an object it is reflected in all directions, some of its back to the eye. This makes the object visible. If the beam of light is moved away, the object will fall into darkness, i.e. no light transmitted to the object therefore none is reflected back and the object is then invisible. Therefore, the direction of the beam gives a good idea of the object. Radar is based on the principal of transmission of high power energy and its reflected by a object encountered in its patch and the reception and display of this reflected energy in a visual form. Most of the modem pulse radar systems use measured bursts of radio energy called pulsed , which after transmission are reflected by the objects, e.g. aircraft, moisture laden clouds, rain drops etc.Classification of RadarsThese are two different types of radar used for ATC namely:- Primary RADAR Secondary RADAR

Primary Radar The receiver of the primary radar detects that small fraction of the reflected signal, which travels back from aircraft to receiver. This radar consists of three basic block of equipment, Transmitter block, received block, and Display Block.DisadvantagesThe efficiency of a primary Radar is poor because the echo signals depend on the target size, materials etc.The transmitter power has to be high because the same energy has to return after getting reflected from the target. The received has to be highly sensitivity because the strength of echoes may be very weak.The critical alignment of the transmitter and receiver frequency is very much essential.The selection response of target is not possible.The echoes from target will cause disturbance in detecting moving targets.Radar frequenciesFrequencies for modem radars are normally selected from approximately 500Mhz to about 100Ghz. Earlier during the development of radars a letter code such as L,S,C,X etc, was employed to designate the radar frequency bands.Secondary RadarHere the active cooperation of target is very much required for finding the range and other details, of the targets. Hence the role of the target is said to be active. Secondary radar system basically consists of two principal components namely the Interrogator, which is ground, based on the Transponder, which carried on the targets. Each of these components consists of a set of pulse transmitter and receiver. The Interrogator radiates pulses which when received by corresponding transponder on a target will initiate a reply from the transponder. The interrogator to extract information about the targets then collects these replies. By suitable coding, some useful information can be conveyed from the target to the ground station.Disadvantages: It can be used for friendly targets only. The system operation depends upon the equipment on the target remaining serviceable. All secondary radars are to be saturatedPulse Radar The most widely used radar which uses pulse modulated microwave signals for their transmission. The pulsed radars can designed for either moving target detection or for radial velocity measurements.Application of Radar:Radar has been employed on the ground, in the air, on the sea and in space. Ground based radar has been used primarily for the detection, location and tracking aircrafts or spacecrafts. Shipboard radar are used n navigational aid and safety device to locate Buoys, shorelines and other ships. Airborne radars are used to detect other aircrafts, ships for land mapping, for weather indication etc. In space radar has assisted in the guidance of guidance of spacecraft and for remote sensing. The major user of radar has been the military, although there have been increasingly important civil application, chiefly for air and marine navigation. The major areas of radar application are briefly described below.Air Traffic Control:Radar are employed throughout the world for the purpose of safe controlling of the always be thought of as radar, altimeter is also a form of radar. Ground mapping radars of moderately high resolution are used extensively these days.AWACS, airborne warning and control system used by USAF are also an airborne radar system.Maritime NavigationRadar is used for enhancing the safety of ship travel by warning of potential collision with other ships and for detecting navigation buoys, especially in poor visibility. Shore based radars of moderately high resolution area used for the surveillance of harbors as an aid to navigation.

Military ApplicationMany of the civilian applications of are also employed by the military. The traditional uses of radar for military application, however, have been to identify enemy aircraft and to control and guide the anti- aircraft guns and surface to air missiles.

Automatic Message Switching System(AMSS) AMSS stands for Automatic Message Switching System. The AFTN (Aeronautical Fixed Telecommunication Network) is a worldwide system of aeronautical fixed circuits provided for the exchange of messages and or digital data between aeronautical fixed stations. These messages are related primarily to the safety of air navigation and regular, efficient, and economic operation of air services. Some circuits of the AFTN are within one state and others are provided as international circuits. In the AFTN, messages are required to be transmitted to a number of addresses. It is impractical for each aeronautical fixed station to be connected physically to all other such stations. Therefore, the AFTN is organized ground a system of relay stations, where in messages and/or digital data are transmitted forward circuits by successive communication centers until they reach their destinations. ECIL AMSS is a computer based AFTN, running on UNIX and windows NT network operating system in which different offices/section of an airport (like AMSS supervisor, HFRT, Booking, ATC, MET etc.) are connected through a Local Area Network (LAN). The local area network of different airports is connected through dedicated leased lines provided by BSNL. The system is meant for automatic establishments. It is more users friendly and faster than TULAMSS and also incorporates additional features like Automatic Self Briefing System (ABSS) and X.25 high speed data link. The ECIL AMSS software can support up to 128 channels.System Configuration:The ECIL AMSS consists of the following components: Ethernet Switch/Hub Workstations/Nodes AMSS Server(s) Disk Switch Database Server(s) X.25/Communication Server Communication Channel Multiplexer (CCM) Adaptor Line Termination Unit (LTU) Rack Patch Panel Rack Remote Printers Uninterrupted Power Supply (UPS) Ethernet Switch /HubEthernet Switch or Hub is a central unit through which all the server and workstation/ nodes are interconnected by LAN cables. The advantage of Ethernet Switch over Hub is that the improved client server response time can be achieved by means of bandwidth sharing when more number of workstations is used.Workstation/Node:Each position (like Supervisor, NOTAM booking, HFRT etc.)is having a personal computer referred as Workstation or Node which consist of Main System Unit, 15 color monitor, TVSE Keyboard, two button mouse and serial printer. The workstations are running on window NT Workstation 4.0 operating system. Any position wants to use ECIL AMSS must run appropriate application program (e.g. supervisor.exe for supervisor position or hfrt.exe for HFRT position) on his workstation.AMSS Server:The AMSS servers are running on SCO UNIX 5.05 operating system. The ECIL AMSS is having two servers; one is configured as SYSTEM A and other as SYSTEM B. At one time only one of the servers can be made online and the other HOT Standby. This is done by running appropriate Unix Shell Scripts (.In or .Ir or .Ih) in respective servers. Both of the AMSS servers are installed with switch over logic control (SOLC) cards. Depending upon which server is online ( SYS A or SYS B); both SOLC cards provide SOLC logic to the LUT rack. The online and Hot Standby server communicate health to each through SLOC cards. The AMSS server is installed with Station card as communication controller module to server multiple numbers of channels. Both the AMSS server is installed with station card as channels. Both the AMSS servers are individually connected to parallel printers. The system generated health/activity information is printed on these printers.Disk Switch: Both the AMSS servers, System A and System B are connected to two SCSI (small computer system interface) disks are referred as DISK 0 and DISK 1. Each SCIS disk and its corresponding connector are housed in a single cabinet and as a whole referred as Disk switch. The SCSI Disk 0 is housed in Disk Switch 01 and Disk 1 is housed in Disk Switch 02 respectively. Each SCSI disk is logically divided into seven logical areas. These are Message area, Incoming MOP area, Outgoing MCP area. Online server stores outgoing & incoming messages on the message areas of both the disks for 30 days. The Ledger area of each disks i.e. Disk 0 and Disk 1 IS Divided into two partitions which are referred as File 0 and File 1. The information that is needed for recovery is stored in this Ledger Area. The online server stores the information required for recovery on these four partitions (File 0, 1Disk0 & File 0, 1 of Disk 1) in sequence in the interval of 30 seconds.The discussion on other areas is beyond the scope of this course. These are discussed in detail in the ECIL AMSS system administrator course.

Data base Server:The data base server is running on Windows NT Server 4.0 operating system. The purpose of this server is to maintain a database of transmitted/received NOTAM/MET/ATC/FIC message traffic is high, more than one-database servers are used for storage of ATC, FIC and MET/NOTAM messages.The RAID controller card is installed in the Database server to connect more than one SCSI disks in an array, called Redundant Array of Inexpensive/Independent Disks (RAID). The advantages of using RAID are manifold. If any one of the disks in the array becomes unserviceable, it can be removed without affecting the functionality of the system. Disk mirroring is also possible if even numbers of disks are used, to enhance data security.

X.25 Server:In airports where traffic is very it is required to send data over a high-speed line and for this purpose X.25 server is used. This server acts as an interface between LAN of any particular airport and X.25 line. The X.25 server is connected to X.25 line through a high speed modem or PAD (Packet Assembler & Dissembler). The X.25 server is also running on Windows NT Server 4.0 operating system and having additional hardware (EICON card) to incorporate X.25 communication interface. CCM Adapters:The CCM adapters are used as the interface between of the UNIX server and the LTU rack. It works in coordination with installation card for multiplexing of messages through different channels.Line Termination Unit (LTU) Rack:The LTU rack consists of its own power supply modules and three types of line termination unit LTU-C, LTU-B/C/M, and LTU-D. The term BICIM refers to the modus of LTU operation. All of these LTU cards are terminated on the same back plane motherboard in the LTU rack.Patch Panel Rack:The Patch Panel, Modems and Line Drivers are housed in this rack.Panel: the output of LTU B/C is connected to TP lines at patch panel using U LINK. Each patch panel module is capable of connected 16 channels. The loop back test for the system side as well as TP lines side can be done by changing the position of Patch U LINK.Modem: Any remote computer can be connected to the ECIL AMSS using Dial up modems.Line Drivers: the line drivers are used to connect remote printers, which are far away from the system site line drivers can drive the line up to a distance of 15kms a 300bps, 12kms at 1200 bps and 8kms at 9600bps, and up to a distance of 2kms at 9.2kbps.REMOTE PRINTERSThe ECIL AMSS is incorporated with Report Printer; Reject Printer located in supervisor position and drop printers located in other position as required. These printers are referred as Remote Printers. The remote printers are connected to UNIX server through LTU C. Report Printer: System generated hourly, half hourly reports and other system information are automatically printers on this on this printer. Rejects Printer: Messages rejected by the system and channel check and miss-chock messages are automatically printer on this printer. Drop Printer: As per the requirement of the station, drop printers can be provided to any location through LTU C.UNINTERRUPTED POWER SUPPLY (UPS)The ECIL AMSS is equipped with a VINTEC Alpha series UPS to supply uninterrupted AC power of high quality to the system, even when the incoming main is cut off completely. The capacity of the UPS depends upon the load. A battery back does the necessary shortage of electric energy. The UPS consists of following basic elements: Rectifier Charger Inverter Battery BankThe rectifier is supplied by the electric utility network AC power. The DC output of the rectifier in turn supplies the inverter and float charges the battery. In the event of failure of the mains supply the inverter is keyed into the system. Being supplied either the rectifier (or so indirectly by the mains) or the Battery; it generates an uninterrupted AC output to feed the critical load. The inverter is protected against overloads, short circuits and overheating etc.

Detailed Block Diagram Description Of HHMD: The coil is part of the oscillation circuit which operation frequency is 23.5 KHz. When a metal object is inside the sensing area of the coil, it will effect to amplitude of the oscillation signal. After a while the integrating control will set the amplitude a constant value. Output of oscillator is rectified and it is connected through the filter section to comparator. When the signal is lower than the adjusted reference level (sensitivity setting) comparator generates alarm signal. It activates the alarm oscillator and audible alarm I the red alarm light. Battery voltage is controlled with a low voltage circuit and constant alarm is activated when the battery voltage is under 7 V. The connector in the rear of the unit operates as headphone and charger connections. The charger idle voltage is between 14 and 24V DC. During charging operation the green light is blinking and with full battery it light constantly. If head phone is connected, audible alarm is not operational.

BLOCK DIAGRAM OF HHMD

Door Frame Metal Detector (DFMD): Almost all airport metal detectors are based on pulse induction (PI). Typical PI systems use a coil of wire on one side of the arch as the transmitter and receiver. This technology sends powerful, short bursts (Pulses) of current through the coil of wire. Each pulse generates a brief magnetic field. When the pulse ends, the magnetic field reverses polarity and collapses very suddenly, resulting in a sharp electrical spike. This spike lasts a few microseconds (millionths of second) and causes another current to run through the coil. This subsequent current is called the reflected pulse and lasts only about 30microseconds. Another pulse is then sent and the process repeats. A typing PI based metal detector greatly based on the manufacturer and model, ranging from about 25 pulses per second to over 1,000. If a metal object passes through the metal detector, the pulse creates an opposite magnetic field in the object. When the pulses magnetic field collapses, causing the reflected pulse, the magnetic field of the object makes it take longer for the reflected pulse to completely disappear. This process works something like echoes: If you yell in a room with only a few hard surfaces, you probably hear only a very brief echo, or you may not hear one at all. But if you yell into a room with a lot of hard surface, the echo lasts longer. In a PI metal detector, the magnetic fields from target objects add their echo to the reflected pulse, making it last a fraction longer than it would without them. A sampling circuit in the metal detector is set to monitor the length of the reflected pulse, by comparing it to the expected length, the circuits can determine if another magnetic field has caused the reflected pulse to take longer to decay. If the decay of the reflected pulse takes more than a few microseconds longer than normal, there is probably a metal objects interfering with it. The sampling circuit sends the tiny, weak signals that it monitors to a device call an integrator. The integrator reads the signals from the sampling circuits, amplifying and converting them to direct currents (DC). The DCs voltage is connected to an audio circuits, where it is changed into a tone that the metal detector uses to indicate a target objects has been founds. If an items is founds, you are asked to remove any metal objects from your person and step through again. If the metal detector continues to indicator the presence of metal, the attends uses a handheld detector, based on the same PI technology, to isolate the cause. Many of the newer metal detectors on the market are multi-zone. This means that they have multiple transmit and receive coils, and each one at a different height. Basically its like having several metal detectors in a single unit.

X-Ray Baggage Inspection System: X-ray Baggage Inspection System is a computer enabled portable equipment to identify any offensive material such as weapon in a sealed baggage. This unit consists of a conveyor belt, which is used to carry the object through the inspection tunnel, where X-ray are incident on the object. This signal is fed to Data Acquisition Card (DAQ), fitted to PC. An analog to digital converter, the part of the DAQ, converts the signal to an 8-bit digital signal. The PC captures digital data produced by the analog to digital converter fitted to the DAQ. This data is then displayed on the monitor screen as the image. The image thus obtained is refined, filtered using different kinds of the images processing techniques. The images edges look. Filters like Embossing filters (north embossed and south embossed), Palladian Filter is applied for the enhancing and detecting the edges that makes the images of the inspected item more discernible. Also, the proposal is a scheme for adaptive Image Contrast Enhancement based on a generalization of Histogram Equalization (HE). HE is useful technique for improving the image contrast, but its effect is too severe for many purposes.

BIBLIOGRAPHY1. Manuals provided by CATC Bamrauli.2. www.google.com3. www.AAI.AERO.com4. www.Wikipedia.com