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Transcript of Rad 7.pptx
Advanced Radioand Radar
Part 7Types of Radar
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 PAR
is to plot the approach of an aircraft
and allow ATC to give accurate guidance
to achieve a safe landing.
The system can be used
in poor weather conditions (i.e. low cloud, limited visibility),
thus reducing interruptions
to a station’s flying programme.
PAR consists of a Radar Head cabin 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.
Precision Approach Radar (PAR)
Height
Bearing
Controlled by the ATC the beams are interlocked, and allows the aircraft to be
"captured" in the beam pattern.
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.
Using both displays the controller is able to guide the aircraft
down a safe "glide path" to approach the runwayon the correct course.
Elevation
Azimuth
Instrument Landing System (ILS)ILS is a runway guidance system
for a safe landing without a ground controllerand provides the pilot with:
a. A visual indication of the aircraft’s azimuth.(on a cockpit instrument)
b. A visual indication of the aircraft’s elevation.(on the same cockpit instrument)
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. Localiser Transmitter.
b. Glide Path Transmitter.
c. Outer, Middle & Inner Marker Beacons.
RUNWAY LTOM MM
GT
IM
Provides Azimuth to keep the aircraft on a central approach line.To give the pilot
elevation information.
Aircraft Passes Outer Marker (5 miles out)
Glide Path Beams Emitted
Passes Middle Marker (¾ mile out)
RUNWAY LTOM MM
GT
RUNWAY LTOM MM
GT
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.
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 centrethe pilot is on the correct glide-path and heading.
The instrument also has warning flags which remain "set" until there is sufficientsignal strength for the system to operate.
Flags Set Signed strength Low
Instrument Landing System (ILS)
Flags Set Signed strength Low
RUNWAY LT
90 Hz
150 Hz
The airfield Localiser Transmitter (LT) radiates two beams,
one at 90 Hz, the other at 150 Hz.
If the aircraft is ‘off’ course to the left, 90 Hz is dominant and the azimuth pointer
moves to the right.
If the aircraft is ‘off’ course to the right,150 Hz is dominant and the pointer moves left.
Instrument Landing System (ILS)
Above Glide-pathBelow Glide-pathOn Glide-path
Flags Retracted Signed strength OK
GTOM MM
90 Hz
150 Hz
RUNWAY
The glide path transmitter sends out 2 beamsmodulated at 90 Hz and 150 Hz
If the aircraft is ‘too high’ on approach, 90 Hz is dominant and the lateral pointer
moves downwards.
If the aircraft is ‘too low’ on approach,150 Hz dominates and the pointer moves upwards.
Digital Resolution Direction FindingGround-based DRDF equipment provides
a direction fix for aircraft, or as an auto-triangulation system.
DRDF provides the controller with information onaircraft 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 pulses from other installationsto 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.
There are two control centres in the UK, one at West Drayton and the other at Prestwick.
Check of UnderstandingWhat are the distinct elements of
a PAR assembly?
Radar cabin, Elevation antennaand Range finder
Radar cabin, Range scanner and Azimuth antenna
Radar cabin, Elevation antenna and Range finder
Radar cabin, Elevation antennaand Azimuth antenna
Check of Understanding
What does PAR stand for?
Primary aircraft radar
Pin-point approach radar
Portable aircraft radar
Precision approach radar
Distance
Elevation
Azimuth
Range
Check of UnderstandingWhat does this screen portray on PAR?
Check of UnderstandingWhat does ILS stand for?
Interim Landing System
Immediate Landing System
Indicator Lights System
Instrument Landing System
Far, Middle and Runway
First, Middle and Final
Outer, Middle and Inner
Distant, Middle and Inner
Check of UnderstandingWhat are the marker beacons in an ILS?
At 1 nautical mile only
Within 25 nautical miles
Under 5 nautical miles only
Over 50 nautical miles
Check of UnderstandingAt what distance could a pilot use ILS?
In this diagram, what state is displayed?
Check of Understanding
Flags set – signal strength high
Flags retracted – signal strength high
Flags set – signal strength high
Flags retracted – signal strength low
Runway bearing number
Azimuth approach angle
Azimuth descent angle
Height to touchdown
Check of UnderstandingWhich of the following
is information supplied to a pilot from ILS?
In this diagram what action should the pilot take?
Gain height
Move left
Lose height
Move right
Check of Understanding
Which three elements make up ILS?
Marker Beacons, Glide-path Transmitter
and Localiser Transmitter
Marker Buoys, Azimuth Antenna
and Localiser Transmitter
Marker Beacons, Azimuth Antenna
and Localiser Transmitter
Marker Buoys, Glide-path Transmitter
and Localiser Transmitter
Check of Understanding
In an aircraft using ILS the meter’s flags are set because . . .
The aircraft is not on beam
The meter needs re-calibration
Signal strength is adequate
Check of Understanding
Signal strength is inadequate
Direct Radar Direction Finding.
Digital Resolution Direction Finding.
Digital Radar Direction Finding.
Direct Resolution Direction Finding.
Check of UnderstandingWhat does DRDF stand for?
Check of UnderstandingDRDF provides the controller with data
in three forms, digital pulses, a DC voltage and which other?
A sinusoidal output
An AC voltage
A sawtooth waveform
Combined digital pulses
Advanced Radioand Radar
End of Presentation