Air craft surveillance & instrumental landing system


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Air craft surveillance & instrumental landing system

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  • Radar is an object detection system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft &ships.Radar uses include:Air traffic control:Precision approach and landing guidance to aircraft.Weather Forecasting / Severe weather detectionMeasuring ocean surface wavesPolice detection of speeding trafficSatellite
  • Super High FrequencySHF3 GHz - 30 GHz0.10m - 0.01m
  • The need to be able to identify aircraft more easily and reliably led to another radar development  SSR-Secondary Surveillance was developed in the late 1960s. It was another form of radar surveillance that receives transmission reflections every few seconds. However, these reflections provide much more data than in primary surveillance. These reflections are digitized messages that report each aircraft's identifications and altitude.These information are transmitted back by the Aircraft’s Transponder on the 1030 MHz back to the ground SSR’s Antennae
  • Radar operates on the 3,000 to 10,000 MHz frequency bands. (super high frequency SHF)Electromagnetic energy radiating outward from a source is reflected back by objects in its path.The time difference between transmission (trace) and reflection (echo) is measured giving an accurate indication of an objects distance.Distance, azimuth, and elevation can be used to fix the objects position in three dimensional space.Signal timing is critical to accuracy. (one microsecond error results in a distance error of almost 500ft.)As a result position accuracy is directly related to the accuracy of the timing device used.An enormous amount of energy must be transmitted in order for even a small amount to be reflected back.Radar must be very powerful as a transmitter and very sensitive as a receiver.This powerful transmitter would completely overpower the receiver. The problem is corrected by alternating the transmit and receive functions at very brief intervals (signal sharing) and at very high rates. (at a range of 40nm radar cycles between transmitting and receiving approx. 800 times/sec.) SHF waves are subject to line-of-sight limitations, which limit range and create problems with terrain masking.Radar has difficulty differentiating between different types of objects.It will show returns from aircraft, terrain, precipitation, flocks of birds, built up areas such as cities.-Primary Surveillance is a form of radar surveillance developed after World War II. It relies on the "skin effect," which is the reflection of the transmitted radar signal from the aircraft's metallic skins. Thus, air traffic controllers were able to observe the horizontal position of the aircraft.Determines the position of contacts by measuring and displaying reflected radio frequency signals from the contacts.The information is displayed to the user on an oscilloscope. (scope)Detects and reports reflections of aircraft, weather, flocks of birds, built-up areas, and terrain.It is a short range radar effective to 80nm.There is no way to tell one aircraft from another without having the pilots verify position.
  • The SSR interrogates aircraft by means of pulse trains forming questions (interrogation mode). Aircraft transponder interpret these questions and transmit back the pulse train which are replies that contain information relate to questions (interrogation). SSR receivers capture these signals and transform them for analysis and processing. SSR is complement to the primary radar as it provide ATC with additional info about aircraft such as aircraft’s call sign, altitude, speed and destination.SSR requires an aircraft to be fitted with transmitter/receiver called as transponder.Secondary Radar The principles of operation of primary radar and some of the factorswhich affect a radar’s performance have been illustrated. Some of the effects can beminimised by using Secondary Radar techniques. The principle of measuring range from atime delay is still applicable, but the target plays an active role.The interrogating radar unit sends out a pulse (interrogation pulse). When this pulse isdetected at the target, it triggers a transmitter to respond, sending a signal back to theinterrogator. This signal will be stronger than an echo, will not be dependent on how well thetarget has reflected the energy and could be coded with additional information.
  • -Secondary Surveillance was developed in the late 1960s. It was another form of radar surveillance that receives transmission reflections every few seconds. However, these reflections provide much more data than in primary surveillance. The transponder is a radio receiver and transmitter which receives on one frequency (1030 MHz) and transmits on another (1090 MHz).
  • Air craft surveillance & instrumental landing system

    1. 1. Air Craft Surveillance & Instrumental Landing System Bikas Chandra Sadashiv ECE – I GNIT 3rd Year
    2. 2. Air Craft Surveillance Through RADAR
    3. 3. Introduction RADAR Frequencies RADAR Applications Types of RADAR Topics To Be Covered
    4. 4. Introduction  RADAR is stand for Radio Detection And Ranging and was developed prior to World War II.  Today RADAR is extremely important in civil aviation.  It is used by ATC to monitor and control numbers of aircrafts in airspace as well as by pilot for weather warning and navigation.
    5. 5. Radar Frequencies  Radar operates on UHF and SHF - Super High Frequency (1 GHz - 30 GHz).  RADAR systems are in SHF bands because: a) These frequencies are free from disturbance. b) Higher frequency, shorter wavelength, RADAR more effective.(shorter wavelengths are reflected more efficiently.)
    6. 6. RADAR Applications RADAR has a wide range applications including 1. Ground RADAR : extensively used by Air Traffic Control to separate aircrafts. 2. Airborne Weather RADAR: used by pilots. It provide pilots with information regarding weather ahead.
    7. 7. Types of RADAR (RSR) En-Route Surveillance Radar TAR- Terminal Approach Radar (PSR & SSR) SMR (Surface Movement Radar) Classifications of RADAR
    8. 8. 1) En-Route Surveillance Radar (RSR)  En-Route Surveillance Radars (RSR) are long range radars which the signal goes to 300 NM.  It operates with frequency between 1 to 2 GHZ.  It used for airway surveillance to provide range and bearing of aircraft. **Surveillance: close observation, especially of a suspected spy or criminal.
    9. 9. 2) Terminal Approach Radar (TAR)  TAR is a high definition radio detection device which provides information on identification, air speed, direction and altitude of aircraft to assist air traffic controllers to track the position of aircraft in the air within the vicinity of the airport.  This radar gives the air traffic controller a better or true picture of all aircraft flying in his control zone.
    10. 10. 2) Terminal Approach Radar (TAR) PSR SSR
    11. 11. Working of PSR :  Primary Surveillance Radar (PSR) transmits a high power signal.  When a signal strikes an object or target, some signal energy is reflected back and is received by the radar receiver.  RADAR receiver will plot the direction and the distance of the target (aircraft) from the radar station.  Thus, the ATC could know the position of aircraft. through the RADAR display. Primary Surveillance Radar (PSR)
    12. 12. Primary Surveillance Radar (PSR) Antenna Transmitted Pulse Target Cross Section Propagation Reflected Pulse (“echo”) Radar observable: • Target range • Target angles (azimuth & elevation) • Target size (radar cross section) • Target speed (Doppler)
    13. 13. Secondary Surveillance Radar (SSR) Working of SSR :  Secondary Surveillance Radar (SSR) transmits an interrogation signal which is received by the target aircraft.  The aircraft transponder sends back a coded reply to the ground radar equipment.  From the coded signal, information of the aircraft’s call sign, altitude, speed and destination.  SSR requires an aircraft to be fitted with transmitter/receiver called as
    14. 14. How SSR Works?  The ground secondary radar transmits 1030MHz signal.  The aircraft radar receives on 1030MHz and transmits back 0n 1090MHz.  The transponder reply is more powerful than the
    15. 15. 3) Surface Movement Radar (SMR)  SMR installed at airport (at top of ATC tower building) to provide a very accurate radar display in all weathers and conditions of visibility. (operate with frequency 18- 40Ghz)  SMR radar display can show all of airfield infrastructure including aircraft movements on runway, taxiway and apron.  It is designed to provide clear display of all aircraft on runway or taxiway so that ATC can ensure runway are clear for take- off/landing and also guide aircraft to apron
    16. 16. 3) Surface Movement Radar (SMR)
    17. 17. RADARS USED IN ATC  Airport Surveillance Radar (ASR)  Air Route Surveillance Radar (ARSR)  Airport Surface movement Detection Equipment (ASDE)/Advanced Surface Movement Guidance & Control System (ASMGCS)  Precision Approach Radar (PAR)  Mono-pulse Secondary Surveillance Radar (MSSR)
    19. 19.  Introduction  The Uses of ILS  ILS Components  How Localizer Works  How Glide Path Works  Marker Beacons Topics To Be Covered
    20. 20. INTRODUCTION Radio beam transmitter that provides a direction for approaching aircraft that tune their receiver to the ILS frequency
    21. 21. The Uses of ILS  To guide the pilot during the approach and landing. ◦ Very helpful when visibility is limited  To provide an aircraft with a precision final approach.  To provide an aircraft guidance to the runway both in the horizontal and vertical planes.
    22. 22. ILS Components  ILS consists of Ground Installations and Airborne Equipments  There are 3 equipments for Ground Installations, which are: 1. Ground Localizer (LLZ) Antenna – To provide horizontal navigation 2. Ground Glide path (GP) Antenna – To provide vertical navigation 3. Marker Beacons – To enable the pilot cross check the aircraft’s height.  There are 2 equipments for Airborne Equipments, which are: 1. LLZ and GP antennas located on the aircraft nose. 2. ILS indicator inside the cockpit
    23. 23. Localizer  Localizer is the horizontal antenna array located at the opposite end of the runway.  Localizer operates in VHF band between 108 to 111.975 MHz
    24. 24. Transmit two signals which overlap at the centre. The left side has a 90 Hz & right has a 150 Hz modulation. The overlap area provides the on-track signal. Right Left How Localizer Works
    25. 25. Localizer Needle indicates direction of runway. Centered Needle = Correct Alignment
    26. 26. Glide Path Antenna Array  Glide Path is the vertical antenna located on one side of the runway about 300 m to the end of runway.  Glide Path operates in UHF band between 329.15 and 335 MHz
    27. 27. How Glide Path Works Glide path produces two signals in the vertical plane. The upper has a 90 Hz modulation and the bottom has a 150 Hz modulation.
    28. 28. Glide Path Needle indicates above/below glide path. Centered Needle = Correct Glide path
    29. 29. Marker Beacons  Marker beacons operating at a carrier frequency of 75 MHz are provided.  When the transmission from a marker beacon is received it activates an indicator on the pilot's instrument panel.  The correct height the aircraft should be at when the signal is received in an aircraft.
    30. 30. Runway Approach Non-Instrument Runway (NI) Non-Precision Runway (NP) Precision Runway (P) Threshold Touchdown zone Aiming point
    31. 31. Types of Runway Approach 1.Non-Instrument Runway (NI) ◦ A runway intended for the operation of aircraft using visual approach procedure 2. Instrument Runway ◦ A runway intended for the operation of aircraft using instrument approach procedures a) Non-Precision Runway (NP) • An instrument runway served by visual aids and a non-visual aid providing at least lateral guidance adequate for a straight-in approach b) Precision Runway (P) • Allow operations with a decision height and visibility
    32. 32. How ILS works?  Ground localizer antenna transmit VHF signal in direction opposite of runway to horizontally guide aircraft to the runway centre line.  Ground Glide Path antenna transmit UHF signal in vertical direction to vertically guide aircraft to the touchdown point.  Localizer and Glide Path antenna located at aircraft nose receives both signals and sends it to ILS indicator in the cockpit.  These signals activate the vertical and horizontal needles inside the ILS indicator to tell the pilot either go left/right or go up/down.  By keeping both needles centered, the pilot can guide his aircraft down to end of landing runway aligned with the runway center line and aiming the touch down.