18 research outputs found

    A comprehensive investigation of retrodirective cross-eye jamming

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    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

    The practical implementation of a retrodirective cross-eye jammer by using software defined radio (SDR)

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    Dissertation (MEng (Electronic Engineering))--University of Pretoria, 2022.Radar-guided missiles have the potential to cause extreme damage to vital military assets. Although traditional deception techniques can deceive radars in range and Doppler shift, only a few methods can deceive them in angle. Cross-eye jamming was identified as a possible countermeasure against angular radar threats. This electronic attack (EA) method works by artificially creating the worst case of glint in angular radars. Numerous analyses of cross-eye jamming exist in the literature. The earlier analyses were derivative glint analyses that made two incorrect assumptions. The first was to use linear fits to the monopulse antenna patterns, which is only valid when the target platform is on broadside of the radar. The second was to assume that the target platform is an infinite distance from the radar, which is not possible. The analyses also did not consider retrodirectivity. It was only during a later cross-eye jamming analysis that the limitations were identified and corrected. The limitations in the analysis could have been identified much sooner if practical measurements were made. The extended cross-eye jamming analysis made fewer assumptions and was proven accurate by numerous simulations and some experimental results. However, the only available experiments where the radar rotation was considered did not implement true retrodirectivity but simulated it by combining isolated channel measurements. A need was identified for the development of a truly-retrodirective cross-eye jammer in a laboratory environment to expand the body of knowledge available about cross-eye jamming. The cost-effective jammer would be used to identify any real-world effects or anomalies that could not be predicted by the extended analysis or identified by simulation. This dissertation presents the development of a truly-retrodirective cross-eye jammer by using a software-defined radio (SDR). The development is accompanied by a method of calibrating the cross-eye jammer to obtain the ideal magnitude factor and phase difference between the retrodirective paths by minimising the magnitude of the sum-channel return of a monopulse radar. The developed system was tested in an anechoic environment against a self-implemented phase-comparison monopulse radar. It was shown that significant angular errors could be induced. The angular errors were larger than 10° at broadside of the radar. This equated to a minimum miss-distance of around 1 m at a range of 6 m. It was shown that a cross-eye gain of around ten was obtained, which resulted in the indicated angle of the radar never becoming zero, regardless of the radar rotation. This suggested that tracking radars, such as that used by active homing missiles, would lose lock on the target platform. Further experiments also proved the jammer to be retrodirective, with large angular errors for all rotations of the jammer antennas. All results correlated very well with that predicted by the extended analysis, with only minor deviations between radar rotations of 0° and 5°. After further investigation, it was concluded that the deviations were most likely caused by mutual coupling between the radar antennas and were not caused by a reduction in the performance of the jammer.Electrical, Electronic and Computer EngineeringMEng (Electronic Engineering)Unrestricte

    Implementation and testing of a retrodirective cross-eye jammer

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    One of the few electronic attack techniques that can deceive radars in angle is cross-eye jamming, which mimics the naturally-occurring phenomenon glint. The extreme tolerance requirements of cross-eye jamming mean that a retrodirective implementation is required, but published measurements of cross-eye jamming either ignore the retrodirective implementation or only simulate it. The implementation of a retrodirective cross-eye jammer and its testing against a monopulse radar are described. A procedure for calibrating the jammer is outlined and is shown to be effective by achieving large angular errors. The measured results agree well with the extended analysis of cross-eye jamming and confirm that the implemented jammer is retrodirective. Specifically, the ability of a cross-eye jammer to generate an indicated angle that never becomes zero, thereby potentially breaking a tracking lock, is confirmed.http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?reload=true&punumber=7hj2023Electrical, Electronic and Computer Engineerin

    Deception jamming against anti-ship missiles which use doppler beam sharpening modes

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    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

    Satellite Power System (SPS) concept definition study (Exhibit D). Volume 2: Systems/subsystems analyses

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    Modifications to the reference concept were studied and the best approaches defined. The impact of the high efficiency multibandgap solar array on the reference concept design is considered. System trade studies for several solid state concepts, including the sandwich concept and a separate antenna/solar concept, are described. Two solid state concepts were selected and a design definition is presented for each. Magnetrons as an alternative to the reference klystrons for dc/RF conversion are evaluated. System definitions are presented for the preferred klystron and solid state concepts. Supporting systems are analyzed, with major analysis in the microwave, structures, and power distribution areas. Results of studies for thermal control, attitude control, stationkeeping, and details of a multibandgap solar cell study are included. Advanced laser concepts and the meteorological effects of a laser beam power transmission concept are considered

    The Final Proceedings of the DOE/NASA Solar Power Satellite Program Review

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    The solar power satellite (SPS) concept defined as 'placing gigantic satellites in geosynchronous orbit to capture sunlight, changing the energy into an appropriate form for transmission to Earth, and introducing the energy into the electric power grid' is evaluated in terms of costs and benefits. The concept development and evaluation program is reviewed in four general areas: systems definition; environmental; societal; and comparative assessments. Specific factors addressed include: transportation, construction in space, methods of conversion of sunlight into energy, transmission to Earth, maintenance in orbit and decommissioning of satellites; environmental, political, and economic effects; and comparison of SPS to other forms of power generation, both terrestrial and in space

    Abstracts on Radio Direction Finding (1899 - 1995)

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    The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

    A Long-range Fine-scale RF Positioning System Using Tunneling Tags

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    Fine-scale positioning systems using inexpensive, low-power, and reliable smart tags enables numerous commercial and scientific applications. Internet of Things (IoT) applications, such as asset tracking, contact tracing, and autonomous driving, require wireless technologies with both the long ranges of conventional wireless links and the low power consumption of passive and semi-passive Radio Frequency Identification (RFID) tags. This dissertation proves that using the Received Signal Phase (RSP)-based positioning method and Tunneling tags at 5.8 GHz breaks the range limit of fine-scale RFID positioning systems. A frequency hopping reader operating in the 5.8 GHz Industrial, Scientific and Medical (ISM) band is designed and implemented in this work. Experimental results yield a one-dimensional distance estimation error of less than 1% at ranges of 100 m when a clear Line-of-Sight (LoS) is available in indoor and outdoor environments. Compared to Received Signal Strength (RSS)-based positioning techniques, the average positioning accuracy is improved by a factor of 51 at ranges of tens of meters. In Non-Line-of-Sight (NLoS) scenarios, the proposed system achieves an estimation error of less than 1.9%. Experimental results also demonstrate that the RSP-based positioning technique allows estimating a mobile reader's two-dimensional position with an average error of 0.17 m in an outdoor environment. Also, a channel sounder implementation using the same hardware configuration further increases the accuracy in multipath environments. Calculation based on the system specifications projects a sub-meter level accuracy at ranges of more than 1 km is feasible using the proposed method.Ph.D
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