EW4 - Electronic Attack - Deception Flashcards

1
Q

Define Deception jamming.

A

The deliberate radiation, re-radiation, alteration, absorption, or
reflection of electromagnetic energy in a manner intended to
mislead the enemy in the interpretation or use of information
received by their electronic systems.

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2
Q

Describe Range Gate Stealing.
(Range Gate Pull Off)

A
  • Early & late tracking gates straddle target echo.
  • AGC circuits set to the desired level for echo strength.
  • Signal amplified & re-transmitted with minimum delay;
  • Strong signal causes the AGC to adjust:
    – Radar then starts to track the false target.
  • Repeated signal successively delayed or advanced on a pulse to-pulse basis away from the true target echo.
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3
Q

Describe Velocity Gate Stealing.

A
  • Works in relation to frequency (Doppler).
  • To steal locking gate, deception signal is shifted in frequency.
  • Captures Doppler filters through the AGC of victim.
  • The false signal is successively increased or decreased in frequency away from the target frequency.
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4
Q

Describe Flare employment

A
  • Designed to decoy IR missiles in terminal phase.
  • Composed of magnesium, teflon & viton (MTV).
  • Composition determines characteristics:
    – Rise time
    – Burn time
    – Energy output
    – Spectral power distribution &;
    – Peak temperature
  • Wavelengths produced must be close to A/C:
  • Current generation flares maximised at 1-3 microns.
  • Countermeasure is to sample the short & long bands;
    – Discard targets with high radiance in lower band.
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5
Q

Describe Flare limitations.

A
  • Only limited number can be carried;
  • Flare flight path & separation may not suit threat;
  • Flare dispensing interval may allow target re-acquisition between flares;
  • Weapons can discriminate against flares on basis of temporal and/or spectral characteristics;
  • Once loaded, flare characteristics cannot be adjusted to match
    aircraft power changes &,
  • Flares not intense enough to protect aircraft using afterburning.
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6
Q

What are the three main types of deception jammers

A

3 Main devices:
* Repeater.
* Transponder.
* Digital Radar Frequency Memory (DRFM).

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7
Q

Describe Repeater Jammer

A
  • Receives, stores, delays & repeats after amplifying.
  • Only responds to pulses & therefore;
  • Only produce false targets at greater distances than true
    target.
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8
Q

Describe Transponder Jammer

A
  • Receives, stores & processes to predict PRI & agility.
  • Is able to pre-empt incoming pulses & therefore;
  • Generate false targets at greater or smaller ranges than true target.
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9
Q

Describe Digital Radar Frequency Memory (DRFM)

A
  • Intercepts and analyses the incoming pulse.
  • Adds:
    – Delays &,
    – Varying Doppler shifts.
  • Therefore can jam coherent Doppler radars.
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10
Q

What is False Target Generation

A
  • Appears on screen as a set of returns which look like targets.
  • Re-transmits signal with slight
    delay:
    – Deceives in range & azimuth (if in side lobes).
  • Overcome by varying PRF (PRI).
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