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EW > EW1 - Electronic Support Systems > Flashcards

EW1 - Electronic Support Systems Flashcards

1
Q

State the stages of the ES process.

(SIIL)

A
  • Search
  • Intercept
  • Identify
  • Locate
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2
Q

State the four ES receiver groups of a conventional system.

A
  • ESM System (SIGINT)
  • Radar Warning Receivers (RWR)
  • Missile Approach Warning Systems (MAWS)
  • Laser Warning Receivers (LWR)
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3
Q

Describe the function of the following ES components: Antennas

A
  • Provide Gain & Directivity.
  • Angular coverage, gain, polarisation, physical size & shape is application dependant.
  • May be an array to provide required angular coverage, polarisation & frequency bandwidth.
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4
Q

Describe the function of the following ES components: Receivers

A
  • Receiver - a device that intercepts transmitted electromagnetic energy and transforms it into useable intelligence.
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5
Q

Describe the function of the following ES components: Signal Processors

A
  • Must deal with many signals (millions of pulses per second)
  • Tasks performed by ES systems include:
    – Deinterleaving Signals.
    – Signal Processing
    – LOB and Fix
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6
Q

Describe the function of the following ES components: Emitter Library

A
  • Produced by EW Support units of platform such as JEWOSU
  • Lists all known emitters in Area of Operations or a refined list to match the required Search Strategy based off the:
    – Electronic Order of Battle (EOB).
  • The library is loaded into the PDS Host Processor via a drive.
    – Also known as ‘Pre-Flight Message’ (PFM)
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7
Q

Describe the Heterodyne principle.

A

** Convert high frequency (GHz) signals into lower frequency (MHz) - Intermediate Frequency or IF.
– Referred as Heterodyning.

  • 2 Signals are mixed in a non-linear device:
    – Received RF input combined &,
    – Oscillator RF input.
  • 2 New frequencies are produced:
    – Sum & Difference of combined inputs.
  • ‘Difference’ frequency used in Superheterodyne Receiver:
    – Lower frequency is normally used as the intermediate-frequency (IF).
    – Other 3 frequencies are filtered out.
  • Multiple stage mixing referred as Super-heterodyning.
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8
Q

Describe the following ES receiver terminology - Frequency coverage

A

The frequency range through which the receiver is able to tune.

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9
Q

Describe the following ES receiver terminology - Selectivity

A

Ability to discriminate signals of close but different frequencies, and amplify only desired signal.

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10
Q

Describe the following ES receiver terminology - Dynamic range

A

The range of signal amplitudes that a device can process without
distortion of the output signal.

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11
Q

Describe the following ES receiver terminology - Sensitivity

A

The smallest detectable signal power a receiver needs to receive in order to distinguish the signal from the noise.

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12
Q

Describe the following ES receiver terminology - Signal to noise ratio

A

The ratio of signal voltage to noise voltage at receiver input or output.

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13
Q

Describe the following ES receiver terminology - Fidelity

Accurate

A

The accurate reproduction of the intelligence. A flat, neutral frequency response

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14
Q

WFHGRSHP

State the requirements of ES receivers.

A
  • have a wide input bandwidth
  • have fine frequency resolution (selectivity)
  • be highly sensitive (able to detect very weak signals)
  • have a good dynamic range (able to detect very strong and very weak signals).
  • receive all polarity signals
  • scan all directions
  • be able to process simultaneous signals
  • have a high POI.
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15
Q

Describe the operation of Scanning Superheterodyne receivers.

A
  • Is a narrow bandwidth receiver.
  • Is swept over frequency range of interest.
  • Sweep stopped on detected signals for analysis.
  • Limited by POI of emitters with scanning antennas
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16
Q

Describe the operation of Channelised Superheterodyne receivers.

A

**Channelised **
* Receiver divides frequency range to be covered into contiguous channels by filters

  • Channel bandwidth determines frequency resolution:
    – i.e., a measure of minimum amount two signals must be separated to resolve them in frequency.
17
Q

Describe signal de-interleaving.

A
  • Extraction of signal of interest from mix of all signals present.
  • Applied in:
    – Time, Frequency & AOA domains.
18
Q

List the parameters that can be measured by ES Systems.

(ARTPPPPSI)

A

– Angle of Arrival (AOA),
– Radio Frequency (RF) and bandwidth (BW),
– Time of Arrival (TOA),
– Pulse Amplitude (PA),
– Pulse Repetition Interval (PRI) / Pulse Repetition Frequency (PRF),
– Pulse Width (PW),
– Polarisation,
– Scan Type and Scan Rate &,
– Intra Pulse and Inter Pulse modulation.

19
Q

Describe Probability of Intercept (POI).

A

** the likelihood that a radar signal emitted by a radar system will intersect (or intercept) with a target object

20
Q

Describe Probability of Report (POR).

A

** POR is the probability that a target signal once detected
will be processed, correctly identified & presented to the
operator within a specified time.

21
Q

EEP

List the factors determining POR.

A
  • Emitter library needs to ensure inclusion of emitter;
  • Emitter library needs to minimise ambiguity &;
  • Processing power in dense signal environments.
22
Q

List the four main methods of direction finding.

A
  • Enables avoidance, EA and engagement with weapons

4 main methods:
– Directional Antenna;
– Amplitude Comparison;
– Phase Comparison (Interferometry) &;
– Time Difference of Arrival (TDOA).

23
Q

Explain the following direction finding methods: Amplitude Comparison

A

Detects the difference in signal amplitude (strength) between
antennas

  • By comparing the Amplitude of the signal at multiple antennas
    you can then calculate the DOA of the signal.
  • Used for both Pulsed & CW signals.
24
Q

Explain the following direction finding methods: Phase Comparison (Interferometry)

A
  • Measures phase difference of incoming signal in each
    antenna;
    – Caused by path distance difference between different antennas.
  • AOA calculated from phase difference.
25
Q

Explain the following direction finding methods: Time Difference of Arrival

A
  • Need ≥ 3 receivers.
  • Measures time of intercept of the signal at each receiver.
  • Calculates Angle of Arrival based on the time difference.
  • Used on Pulse Signals
26
Q

Describe Emitter fixing

A
  • By using multiple bearings we can determine a position of
    emission.
  • This is performed by Passive Detection Systems where as RWR Systems are generally LOB only.
  • Direction measured from 2 separate vantage points:
    – From ≥ 2 separate receivers (Potentially multiple assets)
    – Single receiver as the receiver moves.
  • This leads to an Area of Probability (AOP).
27
Q

What is super heterodyning

A

Multiple stage mixing referred as Superheterodyning

EW (7 decks)

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