Radar Transmission And Processing

Question 1

What are the two many ways of removing unwanted returns on Radar?

Answer 1

Moving Target Indicator (MTI)

Circular Polarisation

Question 2

What type of clutter does circular polarisation remove?

Answer 2

Weather clutter

Question 3

Is circular polarisation switched on continuously?

Answer 3

No because it can mask some returns.

Question 4

Is it possible to stop circular polarisation from masking returns?

Answer 4

Yes. The receiver can be gated to ignore such returns and allow a/c to be seen.

Question 5

What is PSR fitted with in order to help move Ground Clutter?

Answer 5

Moving Target Indicator (MTI)

Question 6

What does MTI remove from the radar screen?

Answer 6

Ground clutter

Question 7

How does MTI work?

Answer 7

It displays echoes from moving targets(aircraft) and rejects echoes from fixed Targets (Permanent Echoes (PE))

Question 8

What is the problem with MTI?

Answer 8

It’s dependent on radial moment of the aircraft between Successive pulses.

If the a/c is flying tangentially/perpendicular to the radar beam the aircraft movement will not have a radial component.

Question 9

If the radar fails to display the radial component of an aircraft on the screen what is called?

Answer 9

Tangential Fading

Question 10

What will happen if the aircraft changes its radial distance by half a
Wave length?

Answer 10

There will be no

Doppler effect and cancellation of the blip will occur. Known as Blind Velocity fading

Question 11

How does Blind Velocity Fading Occur?

Answer 11

When aircraft fly directly towards or away from the radar scanner

Question 12

Blind Velocity fading will also occur when the distance is a multiple of half a wavelength true or False?

Answer 12

True.

Question 13

The speed at which blind Velocity fading occurs is known as

Answer 13

Blind velocities

Question 14

List the 4 ways of data being transmitted.

Answer 14

1) Microwave link
2) Satellite
3) Line of site
4) Telephone/fibre optic cable

Question 15

The method of Transmitting data will depend on 2 factors.

Answer 15

1) The nature of the signals (analogue or digital)

2) The distance to be covered

Question 16

Describe Coaxial cables

Answer 16

1) Limited to Shirt Distance
2) Expensive
3) signal deteriorates rapidly

Question 17

Describe Radio Link

Answer 17

1) Operates in SHF + UHF frequency band
2) for long distance radar information must be monitored and repeated at various stages along the route.
3) To avoid Interference the frequency is changed at each radio link repeater

Question 18

Fibre Optics

Answer 18

Used for relatively short distances (e.g. between radar site and control tower)

Question 19

Can telephones be used for data transmission?

Answer 19

If they are sufficiently high grade and if the information being sent in a processed form (digital Forma plot extractor)

Question 20

Use of plot extractors at radar sites

Answer 20

High grade transmission line la and suitable error checking process enables a high standard of reliability to be maintained.

Question 21

How can caps in radar coverage be reduced/eliminated?

Answer 21

If information from a variety of sources can be presented on display.

Question 22

To achieve reducing gaps in radar display the airspace is divided into a grid of squares. What are the size of the squares? What do they form?

Answer 22

16nm x 16nm

Columns of air from the ground upwards called Radar sort boxes

Question 23

How many radar systems can be in a Radar Sort Box?

Answer 23

Up to 4

Depending on the number of systems which can provide a service.

Question 24

The radar giving the best cover in the Radar Sort Boxes is nominated the?

Answer 24

Preferred

Question 25

The radar providing the next best cover in the Radar Sort Boxes is the

Answer 25

Supplementary

Question 26

The remainder radars in the Radar Sort Box which is neither the preferred or Supplementary make up the?

Answer 26

Reserve

Question 27

If the preferred radar fails the Supplementary radar can be upgraded either manually or automatically to “preferred” and a reserve upgrades to “Supplementary”.
True or False?

Answer 27

True.

Question 28

List the 8 things the Plot Extractor does

Answer 28

1) Decides validity of Targets
2) Calculates correct azimuth and range data
3) Decides is target is primary, secondary or a combination
4) Correlates code data in both identity and height modes
5) Checks for emergency/radio fails and SPI indicators
6) Produces one complete target report per a/c per aerial revolution and outputs this in digital form
7) Produces synchronised message
8) Produces North Mark messages

Question 29

Data from the flight plan database can be processed with radar signal date, enabling useful information to be presented on the radar screen. This includes:

Answer 29

1) conversion of SQK to a/c callsign

2) A/C destination included in radar response label

Question 30

By examining the past movement of radar returns the signal processor can calculate and display ground speed.

True or False?

Answer 30

True.

Question 31

The process of flight can be displayed as trail dots and predictions of the future position of the aircraft can also be displayed by the signal processor.
True or False?

Answer 31

True.

Question 32

List all 5 moveable data

Answer 32

1) DF Bearing Lines
2) Electronic Range n Bearing Marker (ERBM)
3) Electronic cursor
4) Symbols
5) Alpha Numerics

Question 33

List all 7 items in display of information (video map)

Answer 33

1) significant points (nav aids)
2) Final approach Track with ranges
3) Airspace restrictions
4) CAS Boundaries
5) Coastlines and Rivers
6) FIR n National Boundaries
7) Latitude and longitude

Question 34

What is Track Fusion?

Answer 34

It is data from several antennae combined in all parts of the screen. processor determines an average position for each aircraft based on returns from Antenna.
Reduces inaccuracies in displayed position.

Question 35

With Track Fusion it can produce an uninterrupted display of aircraft even if one radar fails. True or False.

Answer 35

True.

Question 36

What does Surveillance Radar Networking do?

Answer 36

Shares radar data with all units in the network.

Provides enhance coverage and extra redundancy and allows multi Radar processing and track fusion.