Outlines of Lecture • Introduction • RADAR Frequencies • RADAR Applications • Types of RADAR
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.
Radar Frequencies • Radar operates on UHF and SHF - Super High Frequency (1 GHz - 30 GHz). • RADAR systems are in SHF bands because: • These frequencies are free from disturbance. • Higher frequency, shorter wavelength, RADAR more effective.(shorter wavelengths are reflected more efficiently.)
RADAR Applications RADAR has a wide range applications including • Ground RADAR : extensively used by ATC to separate aircrafts. • Airborne Weather RADAR: used by pilots. It provide pilots with information regarding weather ahead.
A) RADAR used by ATC • Ground RADAR used by ATC are used to fix an aircrafts position which allows ATC to separate aircraft and guide the pilot. • Three ground RADAR systems used by ATC include 1. En-Route Surveillance Radar (RSR) 2. Terminal Approach Radar (TAR) • Primary Surveillance Radar (SSR) • Secondary Surveillance Radar (SSR) 3. Surface Movement Radar (SMR)
En-RouteSurveillanceRadar(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.
2) TerminalApproachRadar(TAR) • TAR is a high definition radio detection device which provides information on • Identification • Air speed • Direction • Altitude of aircraft • It is use to assist ATC to track the position of aircraft in the air within the vicinity of the airport. Vicinity = Surrounding region / neighborhood.
2) TerminalApproachRadar(TAR) • This radar gives the ATC a better or true picture of all aircraft flying in his control zone . • Enable him to effect separation of aircraft to a finer degree than possible with information exchange by voice communication between the pilot and the controller.
2) TerminalApproachRadar(TAR) SSR PSR
a) Primary Surveillance Radar (PSR) HOW PSR works • 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.
a) Primary Surveillance Radar (PSR) • 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
Advantages of PSR • The advantage PSR is that it operates totally independently of the target aircraft. • Means that no action from the aircraft is required for it to provide a radar return. • But PSR only provide direction and distance of aircraft.
Disadvantages of PSR • First, the signal can be interruptedby buildings, hills & mountains. • Second, more power must be radiated to ensure returns from the target. • Third, because of the small amount of energy returned at the receiver, reflected signals may be easily disrupted. This may cause the displayed target to 'fade‘ (not clear).
b) Secondary Surveillance Radar (SSR) HOW SSR works • 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 transponder.
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 reflected radar signal allowing for far greater range. (250nm).
Secondary Radar Display What appear on secondary radar display? • Aircraft Identity. • Altitude • Speed • Direction/Destination • Example MH092 FL280 585 • Meaning: Flight Malaysian 092 cruising at 28’000ft with speed of 585knots
Advantages of SSR • Requires much less transmitting power to provide coverage up to 200 to 250NM. • Provides more information: aircraft’s identity (its code & call sign), indicates aircraft’s altitude, speed & destination. • Reply signal is much stronger as it does not rely on returning reflected signals.
3) SurfaceMovementRadar(SMR) • SMR installed at airport (at top of ATC tower building). • SMR provide a very accurate radar display in all weathers and conditions of visibility. • SMR radar display can show all of airfield infrastructure including aircraft movements on runway, taxiway and apron.
3) SurfaceMovementRadar(SMR) • 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 • guide aircraft to apron in order.
3) Surface Movement Radar (SMR) • The surface movement radar (SMR) allows the Air Traffic Controller to 'see' in real time the aircraft and vehicles movements into the airport control area. • Surface movement radar can improve both safety and efficiency of airport traffic by providing the ground controller with a clear picture of the areas or under poor visibility conditions.