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Math!!!! > EO-4 > Flashcards

EO-4 Flashcards

1
Q

Modulator

A

A switch used to trigger the transmitter on and off to release bursts of DC energy.

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2
Q

Timer

A

Provides a stable timing source for the entire radar system. AKA the “synchronizer”.

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3
Q

Transmitter

A

High-power oscillator, generates a high-power radio frequency wave for the duration of the input pulse from the modulator. (Converts DC energy into RF energy)

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4
Q

Oscillator

A

An electronic circuit that generates periodic, oscillating signals. (Convert DC from a power supply to AC signal)

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5
Q

Amplifier

A

A device used to increase the power of a signal. (Increases the strength of the RF before transmission)

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6
Q

Duplexer

A

Protects the receiver from the high-power signals that the transmitter produces.

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7
Q

Reciever

A

Converts RF energy into electrical current to be processed. (Can consist of many different components)

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8
Q

Signal Processor

A

The part of the system which separates targets from clutter on the basis of Doppler content and amplitude characteristics.

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9
Q

Matched Filter

A

Maximizes the SNR ratio by filtering out returned energy that does not match what was transmitted.

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10
Q

Low-Noise Amplifier

A

Located at the first stage of the receiver, Increases amplitude level of the target, Sets the noise floor of the radar system.

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11
Q

Antenna

A

Focuses radio waves in a desired direction, provides the ability to measure angle to a target, gives transmitted waves a boost (Gain).

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12
Q

What are the 2 basic/major types of Transmitters?

A

Coherent, Non-Coherent

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13
Q

What are the 2 common categories of oscillators?

A

Magnetron, Solid-State

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14
Q

Coherent Pulse Train

A

The pulses generated are made from a common, underlying waveform. (All pulses are in phase with each other)

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15
Q

Non-Coherent Pulse Train

A

Do not have a common underlying sine wave, the starting phase of each recurring pulse is completely random and not influenced by previous pulses

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16
Q

Magnetron

A

Has the ability to generate high-amplitude RF signals due to the amount of electrical current they can handle.

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17
Q

What are the drawbacks of using magnetrons?

A

Generally non-coherent, systems employing them cannot use certain kinds of specialized signal processing

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18
Q

Exciter

A

A unit that generates wave forms used in the transmitted signal. (Typically don’t generate RF with enough power for radar use and, usually, must be boosted with an amplifier)

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19
Q

What are the 2 parts of a radar exciter?

A

Waveform generator, upconverter

20
Q

Waveform Generator

A

Creates and shapes the waveform modulation

21
Q

Upconverter

A

Translates the waveform to the transmitted carrier frequency

22
Q

Name some types of amplifiers.

A

cross-field amplifiers, klystrons, traveling wave tubes (TWT)

23
Q

What are some considerations in choosing the right amplifier for a radar system?

A

Power requirements, bandwidth limitations, stability, cost, size, weight, and application.

24
Q

What could happen if power from the transmitter “leaked” into the receiver?

A

The receiver would likely be damaged or cease to function.

25
Q

Duplexers are necessary in what type of radars?

A

They are necessary in radars using a single antenna for both transmission and reception, called “monostatic” radars.

26
Q

Bistatic radars

A

Radars with separate antennas for transmit and receive functions.

27
Q

Moving Target Indicator (MTI) Processor

A

System processor to display echoes from moving targets (i.e. aircraft) and to reject echoes from fixed targets (i.e. permanent echoes)

28
Q

Pulse Integrator

A

Processing method that can achieve target detection where individual signal returns would be too low in power to be identified as a target.

29
Q

Pulse Doppler (PD) Processing

A

Primary wat that radar systems measure relative velocity of targets.

30
Q

Target Detector

A

Determines if a target is present in each range or Doppler bin.

31
Q

Display

A

Component of the radar system that enables the operator to read the output of the radar

32
Q

Impedance

A

opposition to the flow of energy

33
Q

Electrical Impedance

A

The measure of the opposition that a circuit presents to a current when a voltage is applied.

34
Q

Inductance

A

The induction of voltages in conductors self-induced by the magnetic fields of currents.

35
Q

Capacitance

A

the ability of a conductor to store energy in the form of electrically separated charges

36
Q

A standing wave occurs when

A

a wave reflects upon itself. (the effects resemble those of jitter)

37
Q

Transmission Lines

A

The wires (overhead or underground) that take electrical current between components.

38
Q

What are the 2 most common types of transmission lines?

A

Coaxial cables, Waveguides

39
Q

Coaxial cable (coax)

A

Cable consisting of a hollow outer cylindrical conductor that surrounds a single inner wire conductor.

40
Q

Waveguide

A

A thin layer or hollow structure in which electromagnetic waves are “guided” from one place to another.

41
Q

What is the most common method for generating timing pulses?

A

The use of a crystal-controlled timer

42
Q

Crystal-controlled Timer

A

A timer that generates the “clock ticking” with an oscillating quartz crystal.

43
Q

Crystal frequency

A

The rate of the crystal’s oscillation, the rate of output “ticks”.

44
Q

Crystal Countdown

A

The number of crystal periods used to create the Pulse Repetition Interval (PRI)

45
Q

Master Oscillator-Power Amplifier (MOPA)

A

Refers to a configuration that uses an oscillator to generate a RF, followed by an amplifier to increase the power of the RF to the required output level.

46
Q

False Alarm

A

Caused by a target detector’s threshold being set too low. (the system perceived a target when none was present)

47
Q

Missed Detection

A

Caused by the target detector’s threshold being set too high. (the system did not perceive a target when one was present)

Math!!!! (7 decks)

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