Browsing by Author "Frazer, Gareth"

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    Deception jamming against anti-ship missiles which use doppler beam sharpening modes
    (2020-02) Frazer, Gareth; Balleri, Alessio; ;
    Missile seekers are becoming increasingly more capable of using Doppler Beam Sharpening (DBS) modes as part of the homing cycle, which requires new countermeasures against this mode. One type of countermeasure, is to create false targets within the seeker DBS image. This thesis presents two implementation methods to insert false targets into DBS images. Both methods are used to create false targets at a precise location within a seeker DBS image, but are implemented in different ways. The first method proposes repeat jamming with a time-varying delay, whilst the second proposes a fixed delay and adding a specific Doppler shift to received waveforms. The effects of tracking errors on the position of the false target are analysed, both analytically and with simulations and used to assess the practical implementation of the jamming scheme. An experimental DBS system was built to test the effectiveness of the jamming scheme against a platform moving in steps and assess errors caused by incorrectly estimating the seeker trajectory. The overall result of the thesis is that using the derived jamming methods, false targets can be created at specific locations in the DBS image of the victim radar, providing the trajectory of the victim radar is known.
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    Deception jamming against doppler beam sharpening radars
    (IEEE, 2020-02-11) Frazer, Gareth; Balleri, Alessio; Jacob, George
    Missile seekers are becoming increasingly more capable of using Doppler Beam Sharpening (DBS) modes as part of the homing cycle, which requires new countermeasures against this mode. One type of countermeasure, is to create false targets within the seeker DBS image. This paper proposes a jamming technique to generate false targets at a precise location within a seeker DBS image, by both delaying and adding a Doppler shift to received waveforms. The effects of tracking errors on the position of the false target are analysed, both analytically and with simulations and used to assess the practical implementation of the jamming scheme. An experimental DBS system was built to test the effectiveness of the jamming scheme against a platform moving in steps and assess errors caused by incorrectly estimating the seeker trajectory.
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    Deception jamming against doppler beam sharpening radars
    (IEEE, 2019-09-16) Frazer, Gareth; Balleri, Alessio; Jacob, George S.
    Missile seekers are becoming increasingly more capable of using Doppler Beam Sharpening (DBS) modes as part of the homing cycle. This paper develops jamming theory and uses it for practical implementation of inserting false targets into a DBS image. The theory is also developed for how incorrect estimations of the seeker trajectory can affect the quality and location of the false target. The simulated and experimental results show how received missile seeker waveforms can be modified to create false targets at desired locations.
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    Jamming Anti-Ship Missile Seekers Which Use Doppler Beam Sharpening Modes
    (Cranfield University, 2017-11-15 12:03) Frazer, Gareth
    3MT presented at the 2017 Defence and Security Doctoral Symposium.This PhD investigates the concept of jamming missile seekers which use a Doppler Beam Sharpening (DBS) mode for target detection and homing. DBS provides a computationally efficient way of improving the cross-range resolution by using the Doppler domain to resolve targets that could not otherwise be resolved with a typical real beamed pulsed radar system. The PhD explores how to use low cost jammers to accurately place false targets in a desired location in the DBS image and the problems which arise when there is a lack of knowledge about seeker trajectory, velocity, waveforms used, etc.
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    Simulations of Repeat Jamming Against Anti-ship Missile Seekers Which Use Doppler Beam Sharpening Modes
    (Cranfield University, 2018-11-19 14:09) Frazer, Gareth
    Poster presented at the 2018 Defence and Security Doctoral Symposium.Doppler Beam Sharpening (DBS) provides a computationally efficient way of improving the cross-range resolution of a radar by using the Doppler domain to resolve targets rather than just using the real beam of the radar. Missile seekers are becoming increasingly more capable of using DBS to home onto targets and this gives rise to the need to jam such systems. This paper presents a set of initial simulations that show how a jammer can interfere with a DBS image. The effects and implications of velocity estimation errors in the jamming module are discussed with respect to a practical implementation of the jammer on a low-cost transceiver.