Week 1

Question 1

What is the formula that converts numbers to dB’s?

Answer 1

(Log X Number) X 10 = dB

Question 2

What is the number that converts dB’s to numbers?

Answer 2

dB/10 = Ans. 10 to the power of Ans = Number

Question 3

Define bandwidth

Answer 3

Bandwidth is the difference between the upper and lower frequencies of the signal. (In Hz)

Question 4

List the four external factors effecting SNR.

Answer 4

Distance from source
Jamming
No LOS/Multi-path interference
Atmospheric conditions.

Question 5

In a Raster Scan, what is a Bar and what is a Frame?

Answer 5

Bar: line of search
Frame: Complete cycle of bars (search area).

Question 6

What are the two types of sector scan?

Answer 6

Bi-directional

Uni-directional

Question 7

Tracking scans include what?

Answer 7

Lobe switching
Monopause
Conical

Question 8

What are the two types of phased array?

Answer 8

Passive

Active

Question 9

What would you expect to see in an antenna design?

Answer 9

Feed
Reflector
Transmitting Medium:
Waveguide & Coaxle

Question 10

Define Beamwidth

Answer 10

The 1/2 power points on the main lobe (-3dB)

Question 11

Benefits small beamwidth

Answer 11

Angular location

Angular discrimination

Question 12

List the types of lobes

Answer 12

Main/major lobe
Side/minor lobe
Back lobe

Question 13

List the types of array/beam steering:

Answer 13

Mechanical

Electrical - Changing Freq & Phase.

Question 14

What does DOA stand for?

Answer 14

Direction of Arrival

Question 15

Describe the term Ellipse.

Answer 15

Very rarely is the DF pinpoint so the position is described as an ellipse.

Question 16

What is an Ellipse?

Answer 16

The length of its major axis
The length of its minor axis
It’s orientation
The position of the centre

Question 17

List the two types of DOA measurements?

Answer 17

Amplitude Comparison

Phase Comparison

Question 18

Differences between phase and amplitude comparison.

Answer 18

Phase can be accurate to 1.5 degrees.

Amplitude is not very accurate - to about 10 degrees.

Question 19

What do most RWRs use?

Answer 19

Power measurement.

Question 20

What is the RWR detection sequence?

Answer 20

Identifies 
Measures received PWR
Compares to the known transmitter PWR 
Range calculated
Warning given.

Question 21

What does RWR rely on?

Answer 21

ELINT gathering

Ability of MA (EW) operators

Question 22

What four things should ES receivers do?

Answer 22

Intercept
Measure
Identify
Display

Question 23

Define Unintentional Pulse Modulation

Answer 23

Unintentional Pulse Modulation is caused by system noise & different operation. It helps with Specific Emitter Identification (SEI)

Question 24

List in order an ES receiver system.

Answer 24

Antennae - Amplifier - Receiver -Processor - Outputs.

Between Receiver & Outputs - DOA Resolver.

Question 25

3 types of ES Receiver

Answer 25

Threat Warning Tactical systems Strategic systems

Question 26

List the 3 types of radar display.

Answer 26

PPI B-scope A-scope

Question 27

List the 6 types of target information

Answer 27

``` Range Bearing Height Course Speed Shape/size/outline ```

Question 28

What are the factors effecting radar?

Answer 28

``` Frequency PRF PW Power Beamwidth ARP Antenna Weight ```

Question 29

Define Isotropic Source

Answer 29

Waves go in all directions equally

Question 30

Label Transmit and Receive Diagram

Answer 30

Synchroniser - Modulator - Transmitter - Switch - Antenna - Receiver - Display

Question 31

List the 3 types of Pulse Modulation

Answer 31

Amplitude Frequency Phase

Question 32

List the 3 Transmission Devices

Answer 32

Magnetron Travelling Wave Tube Field Effect Transistor

Question 33

3 uses of Radar Systems

Answer 33

Military uses Weather Nav Aids

Question 34

What are the 2 main things in a Radar System

Answer 34

Transmitter | Receiver

Question 35

3 types of fading

Answer 35

Skip Fade Multi path Fade Polarisation Fade

Question 36

What two layers of the Earths Atmosphere have most major effect on EM waves?

Answer 36

Ionosphere | Troposphere

Question 37

What does MUF stand for?

Answer 37

Max usable frequency

Question 38

What is a Temperature Inversion caused by?

Answer 38

Warm air moving over cold air. The sea keeping lower layers cooler than the air above it The earth at night cooling and conducting heat away from the air above it.

Question 39

List 3 prime areas for temperature inversions to occur

Answer 39

North Africa Middle Easy Mediterranean

Question 40

Where to atmospheric anomalies take place?

Answer 40

Troposphere

Question 41

List the 4 wave types

Answer 41

Ground waves Surface waves Space waves Sky waves

Question 42

Define Reflection

Answer 42

Angle of incidence = angle of reflection, as measured from the normal to the surface. The incident ray & reflected ray lie in the same plane.

Question 43

Reducing what is important for stealth aircrafts?

Answer 43

Glint & Scintillation

Question 44

What are the 2 types of attenuation?

Answer 44

Absorption | Scattering

Question 45

Define atmospheric attenuation

Answer 45

The weakening of signal at is propagates through the atmosphere

Question 46

Define power density

Answer 46

The amount of energy per unit area

Question 47

What are the 3 types of Polarisation?

Answer 47

Random Linear Circular & Elliptical

Question 48

What form a square wave?

Answer 48

Odd harmonics

Question 49

How far does an EM wave travel in 1 microsecond?

Answer 49

300m 984ft 0.162NM

Question 50

Define Analogue System

Answer 50

Some sources consist of a variable quantity which changes continuously through time.

Question 51

Define Digital Signal

Answer 51

Consists of a series of discrete permitted values with time.

Question 52

To convert GHz to MHz what do you do?

Answer 52

Take away 6 zeroes.

Question 53

What are the 3 measurements for the speed of light

Answer 53

3 X 10 to the 8 162000 Nm/s 186000 M/s

Question 54

What does RADAR stand for?

Answer 54

Radio Detection and Ranging

Question 55

What two fields are there in terms of EM waves?

Answer 55

H-Field | E-Field

Question 56

What is SNR

Answer 56

Signal to Noise Ratio. | The ratio that describes a radars ability to see targets in presence of noise.

Question 57

List 3 types of internal noise

Answer 57

Equipment noise Antenna noise Transmission noise

Question 58

What is an advantage of an active phased array over a passive phased array?

Answer 58

Active is multifunction, if damaged you can turn off damaged cells and the rest will carry on working.

Question 59

What function would you expect a radar with the following parameters to have? Freq 1.3GHz PRF 300 PW 9 ARP 8

Answer 59

LREW