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

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

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

Implementation and testing of a retrodirective cross-eye jammer

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

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

Modulated Microwave Retro-reflectors and Their Applications

This work seeks to investigate the viability of establishing communications links using modulated microwave reflectors, and explores potential application areas. A primary and underlying objective has been to combine modulation of radar cross section (RCS) with the wide-angle RCS response of a microwave retro-reflector so as to yield a transponder which imparts information content on the reflected spectrum. Since the RCS is electrically large, the communications link is directive and yet the transponder is not a transmitter of microwave energy and hence has modest power needs. The microwave retro-array was quickly identified as the most promising structure to achieve these aims, and hence the further objectives of the work have been to investigate this structure and fabricate working prototypes so as to: • achieve a manufacturable structure. • perform measurements to compare with theoretical models of behaviour. • explore the limits of performance, and seek to expand them. • identify applications and markets. • explore and pursue such related discoveries that may occur. All the above aims have been explored to some extent, and the findings have been reported in the body of the thesis. The background and historical context is discussed in chapter 1, while chapter 2 reports on the construction and characterisation of 16- element modulated retro-array prototypes operating at a 2.5 GHz carrier frequency. The applied nature of this work is extended in chapters 3 and 4 to printed integrated circuits for passive transponders, and the scaling of these methods to frequencies around 9.2 GHz. Theoretical models for the properties of much larger arrays are presented in chapter 5, and range finding applications and results presented in chapter 6. Two applications are then discussed for which the required array dimensions are estimated, before closing with conclusions and suggestions for future work

NASA Thesaurus. Volume 2: Access vocabulary

The NASA Thesaurus -- Volume 2, Access Vocabulary -- contains an alphabetical listing of all Thesaurus terms (postable and nonpostable) and permutations of all multiword and pseudo-multiword terms. Also included are Other Words (non-Thesaurus terms) consisting of abbreviations, chemical symbols, etc. The permutations and Other Words provide 'access' to the appropriate postable entries in the Thesaurus

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

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

NASA thesaurus. Volume 2: Access vocabulary

The Access Vocabulary, which is essentially a permuted index, provides access to any word or number in authorized postable and nonpostable terms. Additional entries include postable and nonpostable terms, other word entries, and pseudo-multiword terms that are permutations of words that contain words within words. The Access Vocabulary contains 40,738 entries that give increased access to the hierarchies in Volume 1 - Hierarchical Listing

Abstracts on Radio Direction Finding (1899 - 1995)

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

NASA thesaurus. Volume 1: Hierarchical Listing

There are over 17,000 postable terms and nearly 4,000 nonpostable terms approved for use in the NASA scientific and technical information system in the Hierarchical Listing of the NASA Thesaurus. The generic structure is presented for many terms. The broader term and narrower term relationships are shown in an indented fashion that illustrates the generic structure better than the more widely used BT and NT listings. Related terms are generously applied, thus enhancing the usefulness of the Hierarchical Listing. Greater access to the Hierarchical Listing may be achieved with the collateral use of Volume 2 - Access Vocabulary and Volume 3 - Definitions