Advanced Radio and Radar Types of RADAR Lecture

Advanced Radio and Radar Types of RADAR Lecture Five

Introduction We have already looked at the general principle of operation of both radio communication and radar. We will now look more closely at a variety of different types of equipment used in the RAF, to see how and where they are used.

Precision Approach Radar (PAR) The purpose of Precision Approach Radar (PAR) is to reduce interruptions to a station's flying programme because of poor weather. It achieves this by using a cross shaped beam to guide aircraft to achieve a safe landing in poor weather conditions (i. e. low cloud, limited visibility etc).

Precision Approach Radar (PAR) PAR consists of a Radar Head connected to the ATCC. The Radar Head can rotate around a central point, so it can serve whichever runway is in use. The Radar Head itself has three distinct assemblies; The Radar Cabin, The Azimuth Antenna, The Elevation Antenna.

Precision Approach Radar (PAR) Narrow beams are transmitted from each antenna. One horizontal (2° wide by 0. 5° high) for height, the other vertical (0. 5° wide by 2° high) for bearing. Bearing Height

Precision Approach Radar (PAR) Controlled by Air Traffic Control the cross shaped beams are interlocked, and allows the aircraft to be "captured" in the beam pattern. Bearing Height

Precision Approach Radar (PAR) The cross beam information is shown on a screen with two displays. One display is of the elevation scan, the other shows the azimuth scan. Elevation Azimuth Using both displays the controller is able to guide the aircraft down a safe "glide path" to approach the runway on the correct course.

Instrument Landing System (ILS) The Instrument Landing System (ILS) is a runway guidance system for a safe landing without a ground controller, and provides the pilot with: a. A visual indication of the aircraft’s azimuth. b. A visual indication of the aircraft’s elevation. c. Both an audio and visual indication of the aircraft’s distance from touch down. d. An audio indication of the identity of the airfield (in Morse code), to confirm landing at the right airfield.

Instrument Landing System (ILS) This system has 3 separate elements: a. A Localiser Transmitter. Provides Azimuth to keep the aircraft b. A Glide-path Transmitter. on a central To giveapproach the pilot line. c. Three Markerelevation Beacons (Outer, Middle & Inner). information. OM MM RUNWAY IM GT LT

Instrument Landing System (ILS) To use the ILS a pilot must position the aircraft in line with the instrument runway at a range of some 20 to 25 miles. Aircraft Passes Outer Marker (5 miles out) The Glide-path Beams are emitted. Aircraft passes Middle Marker (¾ mile out) 20 to 25 miles and lands safely. from runway OM MM RUNWAY GT LT

Instrument Landing System (ILS) The pilot has a 2 -point meter. One gives the lateral direction to fly (left or right), the other gives the vertical direction (up or down). When the two pointers cross in the centre the pilot is on the correct glide-path and heading.

Instrument Landing System (ILS) The pilot has a 2 -point meter. The instrument also has warning flags which remain "set" until there is sufficient signal strength for the system to operate. Flags Set Signal strength Low

Instrument Landing System (ILS) The airfield Localiser Transmitter (LT) radiates two beams. If the aircraft is ‘off’ course to the left, the azimuth pointer moves to the right. If the aircraft is ‘off’ course to the right, the azimuth pointer moves left. Viewed from RUNWAY Aircraft isis. Right is onof Glide-path of. Glide-path Aircraft Left Flags Set Signal strength Low LT above

Instrument Landing System (ILS) The Glide-path Transmitter also sends out 2 beams. If the aircraft is ‘too high’ on approach, the lateral pointer moves downwards. If the aircraft is ‘too low’ on approach, the lateral pointer moves upwards. Viewed from the side OM MM Aircraftisisabove below on Glide-path NOTE Flags Retracted Signal strength OK GT RUNWAY

Digital Resolution Direction Finding equipment provides a direction fix for aircraft, or as an auto-triangulation system. DRDF provides the controller with information on aircraft bearings in the following forms: a. Digital pulses to give a digital read-out and a vector display. b. Direct Current (DC) voltage proportional to the angle of the bearing. c. Combined digital pulses from other installations to triangulate the aircraft’s position.

Digital Resolution Direction Finding DRDF is used primarily for aircraft in distress, by accurately pinpointing an aircraft. The ‘distressed’ aircraft transmits a code used to determine a directional bearing of the aircraft. Using similar information from other installations, the aircraft’s position is triangulated.

Digital Resolution Direction Finding DRDF is used primarily for aircraft in distress, by accurately pinpointing an aircraft. There are two control centres in the UK, one at West Drayton and the other at Prestwick.

Check of Understanding What is the purpose of PAR ? To allow flying at all times in the area of the airfield To reduce interruptions to a station's flying programme because of poor weather To allow flying in good visibility in the area of the airfield To reduce interruptions to a station's flying programme because of high cloud

Check of Understanding How many distinctive assemblies does PAR consist of: One Two Three Four

Check of Understanding What does PAR stand for? Pin-point approach radar Precision approach radar Portable aircraft radar Primary aircraft radar

Check of Understanding What are the distinct elements of a PAR assembly? Radar cabin, Elevation antenna and Azimuth antenna Radar cabin, Elevation antenna and Range finder Radar cabin, Range antenna and Azimuth antenna Radar cabin, Elevation scanner and Range finder

Check of Understanding Transmitters close to the runway let the pilot know when his aircraft is on the correct flight path. These signals are fed into the ILS which stands for? Immediate Landing System Interim Landing System Instrument Landing System Indicator Lights System

Check of Understanding Which of the following is information supplied to a pilot from ILS? Direction of prevailing wind Airfield's height above sea level Airfield identification Diversion airfields

Check of Understanding Which three elements make up ILS? Marker Buoys, Azimuth Antenna and Localiser Transmitter Marker Buoys, Glide-path Transmitter and Localiser Transmitter Marker Beacons, Azimuth Antenna and Localiser Transmitter Marker Beacons, Glide-path Transmitter and Localiser Transmitter

Check of Understanding What information comes from an ILS Localiser? Azimuth Height Elevation Range

Check of Understanding How many marker beacons are there in an ILS system? One Two Three Four What are these marker beacons called? First, Middle & Final Distant, Middle & Inner Outer, Middle & Inner Far, Middle & Runway

Check of Understanding In an aircraft using ILS the meter's flags are set because: The signal strength is inadequate The aircraft is too close to the airfield The signal strength is adequate The pilot has not calibrated the meter

Check of Understanding At what distance could a pilot use ILS? Over 50 nautical miles Within 25 nautical miles Under 5 nautical miles only At 1 nautical mile only

Check of Understanding In this diagram, what state is displayed? Flags retracted – signal strength high Flags set – signal strength high Flags retracted – signal strength low Flags set – signal strength high

Check of Understanding The RAF uses which equipment for direction finding? DRDF DFAC DADF DTAF

Check of Understanding What does DRDF stand for? Digital Resolution Direction Finding. Direct Resolution Direction Finding. Digital Radar Direction Finding. Direct Radar Direction Finding.

Check of Understanding DRDF provides the controller with data in three forms, digital pulses, a DC voltage and which other? An AC voltage Combined digital pulses A sawtooth waveform A sinusoidal output

Check of Understanding There are two main control centres used in the DRDF system one is Prestwick, the other is at? West Wycombe West Raynham West Drayton West Ham

Check of Understanding Which radar employed by the RAF can be rotated to serve the runway in use? DRDF ILS PAR Non of the above

Check of Understanding Which radar, employed in the RAF, uses a cross shaped beam to guide aircraft to a safe landing? DRDF ILS PAR None of the above

Advanced Radio and Radar End of Presentation