158 research outputs found
Limiting apparent target position in skin-return influenced cross-eye jamming
It is desirable to limit the apparent target to one side of a retrodirective cross-eye jammer despite the variation
caused by platform skin return. The relationship between the jammer parameters and the jammer-to-signal ratio
(JSR) to ensure that this occurs is investigated. When this relationship is not satisfied, the proportion of the
apparent targets generated on the opposite side of the jammer is determined.This work was supported by the Armaments Corporation of South
Africa (Armscor) under Contract KT521896.http://ieeexplore.ieee.org/arnumber=6558044hb201
Statistical skin-return results for retrodirective cross-eye jamming
The effect of the radar skin return from the platform on which a cross-eye jammer is mounted is significant in many practical cross-eye jamming scenarios. However, all published analyses of skin-return affected cross-eye jamming have significant limitations. These limitations are addressed by deriving equations for the distribution of the cross-eye gain in the presence of skin return. The values of these results are demonstrated by using them to gain insight into how skin return affects cross-eye jamming.The National Research Foundation of South Africa (Grant number 119151).http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?reload=true&punumber=7hj2019Electrical, Electronic and Computer Engineerin
Path-length compensation in multi-loop retrodirective cross-eye jamming
Multiloop retrodirective cross-eye jammers offer the possibility of both simplifying system implementation and improving system performance. However, the signals for each jammer loop propagate along different paths, leading to potentially detrimental effects on system performance. Static and dynamic compensation for path-length differences are introduced and analyzed. Of the two, static compensation is simpler but is only effective for limited engagement geometries. Dynamic compensation is more general but requires an accurate estimate of the engagement geometry.http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?reload=true&punumber=7hj2019Electrical, Electronic and Computer Engineerin
Efficient computation of array factor and sidelobe level of linear arrays
The implementation of code to efficiently compute the array
factor and sidelobe level (SLL) of linear antenna arrays in MATLAB and
GNU Octave is considered. The use of a fast Fourier transform (FFT)
to compute the array factor is shown to be more efficient than other
approaches. The automatic determination of the sidelobe region as a
necessary step to computing the SLL is addressed. A number of codeoptimsation
techniques in MATLAB and Octave are evaluated, including
vectorisation, memory allocation and the use of built-in functions. Finally,
an efficient function which can be used for the computation of the array
factor and SLL of linear arrays in MATLAB and Octave is presented.This work is based on the research supported
in part by the National Research
Foundation (NRF) of South Africa
(grant-specific unique reference number
85845).http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=74hb2017Electrical, Electronic and Computer Engineerin
Analysis of path-length effects in multiloop cross-eye jamming
The effect of path-length differences on multiloop retrodirective cross-eye jammers is evaluated. It is shown that such jammers may act as beacons, and the conditions under which this occurs are investigated for two-loop jammers. The sensitivity of the two-loop cross-eye gain to path-length differences is also studied and is found to be small for small path-length differences, but to increase rapidly. The effect of the two-loop cross-eye jammer parameters on path-length effects is also considered.The National Research Foundation of South Africa (NRF) [85845http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?reload=true&punumber=7hj2017Electrical, Electronic and Computer Engineerin
Cross-eye gain in multiloop retrodirective cross-eye jamming
The simultaneous use of multiple retrodirective
cross-eye jammers is analysed for both the case
where the jammer loops point in different directions and
when they point in the same direction. In both cases, the
use of multiple cross-eye jammer loops is shown to lead to
significantly increased angular errors in the threat radar
under certain conditions. Alternatively, the sum-channel
return can be increased to reduce the jammer-to-signal
ratio (JSR) requirements for each jammer loop.http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?reload=true&punumber=7hb2016Electrical, Electronic and Computer Engineerin
Phaseâconjugating retrodirective crossâeye jamming
A crossâeye jammer based on a phaseâconjugating (PC) retrodirective array is proposed. Such PC crossâeye jammers eliminate the delay inherent in traditional VanâAtta (VA) crossâeye jammers and induce errors in radars that use the same antenna beam for transmission and reception, while VA crossâeye jammers do not. Validated simulations are provided to confirm the effectiveness and retrodirective properties of the PC crossâeye jammer.https://ietresearch.onlinelibrary.wiley.com/journal/1350911xhj2021Industrial and Systems Engineerin
Statistical skin-return results for retrodirective cross-eye jamming
The effect of the return from the platform
on which a cross-eye jammer is mounted is significant
in many practical cross-eye jamming scenarios. However,
all published analyses of skin-return affected cross-eye
jamming have significant limitations. These limitations are
addressed by deriving equations for the distribution of the
cross-eye gain in the presence of skin return. The value of
these results is demonstrated by using them to gain insight
into how skin return affects cross-eye jamming.http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?reload=true&punumber=7hb2017Electrical, Electronic and Computer Engineerin
A comprehensive investigation of retrodirective cross-eye jamming
Cross-eye jamming is an Electronic Attack (EA) technique that induces an angular error in the radar being jammed. The main benefit of cross-eye jamming is that it is effective against monopulse tracking radars, which are largely immune to other forms of jamming. The objective of this research is to gain a complete understanding of cross-eye jamming so that systems that might be developed in future can be properly specied. The main contribution of this work is a comprehensive mathematical and experimental study of retrodirective cross-eye jamming. The mathematical analysis considers all aspects of an isolated, single-loop, retrodirective cross-eye jamming engagement, thereby avoiding the approximations inherent in other cross-eye jamming analyses. Laboratory experiments that accurately represent reality by using the radar for both transmission and reception, and simulating a true retrodirective cross-eye jammer were performed to validate the theoretical analysis. Lastly, the relationship between the angular error induced in the radar being jammed and the matching required from a cross-eye jammer system is explored. The most important conclusion of this work is that the traditional analyses of cross- eye jamming are inaccurate for the conditions under which cross-eye jammers operate. These inaccuracies mean that the traditional analyses are overly conservative, particularly at short ranges and for high cross-eye gains, suggesting that practical cross-eye jammers can be realised more easily than is generally believed.Thesis (PhD)--University of Pretoria, 2010.Electrical, Electronic and Computer Engineeringunrestricte
Specific emitter identification for enhanced access control security
This paper presents the application of specific emitter
identification (SEI) to access control and points out the security
caveats of current radio-based access remotes. Specifically,
SEI is applied to radio frequency (RF) access remotes used to
open and close motorised gates in residential housing complexes
for the purposes of access control. A proof-of-concept SEI system
was developed to investigate whether it is possible to distinguish
between the RF signals produced by two nominally-identical
access remotes. It was determined that it is possible to distinguish
between the remotes with an accuracy of 98%.The National
Research Foundation (NRF) (Grant specific unique reference number (UID)
85845).http://www.saiee.org.za/DirectoryDisplay/DirectoryCMSPages.aspx?name=Publications#id=1588&dirname=ARJ&dirid=337hb2017Electrical, Electronic and Computer Engineerin
- âŠ