Transmitters & Receivers Flashcards

1
Q

What devices are used in the Modulator in a HPO

A

Pulse forming network

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2
Q

What device is used in the RF oscillator in a HPO

A

Multi cavity Magnatron

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3
Q

Characteristics of a HPO

A

Large in amplitude
Rectangular
Precise in width

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4
Q

Advantages of MOPA over HPO

A

Low power modulator
Frequency stability
Phase coherence

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5
Q

What is the function of a video detector

A

Demodulates the bi-polar pulse

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6
Q

Func of a Video amp

A

Provides sufficient gain for pulse waveform to drive display

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7
Q

Techniques to reduce clutter

A

Fast time constant
Swept gain
Logarithmic IF amps

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8
Q

Explain staggered tuning

A

By tuning each stage of the IF amp to a different frequency the bandwidth is widened without reducing voltage output

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9
Q

Explain operation of swept gain

A

Reduces Rx gain to reduce near ground clutter

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10
Q

Explain operation of logarithmic IF amplifiers

A

Small signals maximum gain
Large signals minimum gain

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11
Q

Noise reduction techniques that reduce noise in radar receiver

A

Adaptive noise reduction
Matched filter

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12
Q

Explain adaptive noise reduction

A

Automatic changes to set noise level to prevent false targets

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13
Q

Matched filter noise reduction

A

BW = 1/PW

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14
Q

What devices are used to produce frequency agility

A

FAMOPA
Spin disc magnetron

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15
Q

Advantages of frequency agile radar over fixed freq radar

A

Less interference
Less clutter
Eliminates 2nd time around echoes

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16
Q

Function of MO and LO in FAMOPA

A

MO - Runs continually - variable output
LO - runs at a constant frequency

17
Q

Radar that use monopulse techniques

A

Terrain following radar
Ground mapping radar
Airborne interception AI

18
Q

What information is obtained from monopulse ranging

A

Slant range
Depression angle

19
Q

Explain the principle of MTI

A

Uses Doppler effect
Identifies moving target on the ground
Can suffer from blind speeds

20
Q

Principle of pulse compression

A

Wide pulses are transmitted to give more energy for long range

Processed as narrow pulses

Good target discrimination

Effects minimum range

21
Q

Advantages of pulse compression in primary pulsed radar systems

A

Some resistance to ECM jamming
Better target discrimination
Longer range
Improved s/n ratio

22
Q

How could pulse compression be improved

A

If more frequencies were used in the transmitted pulse, this would result in a narrower pulse with a higher amplitude

23
Q

What will give good target velocity info in pulsed Doppler radar

24
Q

What will give good target range information in pulsed Doppler radar

25
What is Eclipsing
Received signal coming in while still transmitting Some of target cut off
26
What is blind ranges
Received signal coming in while still transmitting All target cut off
27
Explain the purpose of S.A.R
Used to produce High resolution image used for ground mapping
28
Advantages of S.A.R over aerial photography
Operational day or night All weather High quality radar map produced
29
Explain ISAR
Generates a 2D high res image The image allows the operator to detect missiles and aircraft Used in shop surveillance as the movement of sea improves the image