Warren Paul du Plessis

Introduction of low probability of recognition to radar system classification

This paper proposes the addition of low probability of recognition (LPR) to the electronic warfare classification of radar systems. LPR radars focus on deceiving electronic support (ES) receivers by selecting waveforms which are agile in their parameter spaces, or by mimicking existing transmitters. LPR provides an additional mechanism to achieve covert operation in a way which builds on low probability of interception (LPI) and low probability of detection (LPD) techniques. The challenges and opportunities of LPR techniques are considered, and some examples of existing waveforms which are suitable for LPR radars are provided.

Cross-eye gain in multiloop retrodirective cross-eye jamming

The simultaneous use of multiple retrodirective cross-eye jammers is analyzed 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 requirements for each jammer loop.

Efficient Computation of Array Factor and Sidelobe Level of Linear Arrays [EM Programmer's Notebook]

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 in this article. 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 code-optimization techniques in MATLAB and Octave are evaluated, including vectorization, memory allocation, and the use of built-in functions. Finally, an efficient function that can be used for the computation of the array factor and SLL of linear arrays in MATLAB and Octave is presented.

Software-defined radio (SDR) as a mechanism for exploring cyber-electronic warfare (EW) collaboration

Cyber is concerned with networks of systems in all their possible forms. Electronic warfare (EW) is focused on the many different uses of the electromagnetic spectrum (EMS). Given that many networks make use of the EMS (wireless networks), there is clearly large scope for collaboration between the cyber-warfare and EW communities. Unfortunately, such collaboration is complicated by the significant differences between these two realms. Software-defined radio (SDR) systems are based on interfaces between the EMS and computers and thus offer tremendous potential for encouraging cyber-EW collaboration. The concept of SDR is reviewed along with some hardware and software SDR systems. These are then used to propose a number of projects where SDR systems allow collaboration between the cyber and EW realms to achieve effects which neither realm could achieve alone.

Path-Length Effects in Multiloop Retrodirective Cross-Eye Jamming

Cross-eye jammers are required to operate in their near-field regions, so path-length differences between the jammers comprising a multiloop retrodirective cross-eye jammer cannot be ignored. The effects of these path-length differences are investigated and are shown to be significant in realistic cross-eye jamming scenarios. Notably, path-length differences have the potential to cause a multiloop retrodirective cross-eye jammer to act as a beacon rather than a jammer when the path-length difference is approximately 180

Numerical Optimization of Compressive Array Feed Networks

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Case study on low probability of recognition (LPR) radar using GSM

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Jammer signal effectiveness against a conical-scan missile seeker

Compressive antenna arrays reduce the number of beamforming controls by taking a limited number of weighted combinations of the element signals. A compressive array sidelobe level (SLL)-minimization algorithm, inspired by coherence-optimization algorithms, is presented. Optimized compressive arrays are shown to obtain better SLLs than existing weighted thinned arrays and completely overlapped subarrays. The design of a compressive array with arbitrary sidelobe requirements shows that increasing the number of elements for a given number of beamforming controls improves the array performance over a conventional array. A compressive array with a hard null is proposed to suppress the interference before sampling. Where beamforming controls are the main cost drivers, the proposed approach promises to increase the array performance without a significant increase in cost.

Analysis of Path-Length Effects in Multiloop Cross-Eye Jamming

A practical investigation of the application of low probability of recognition (LPR) to Global System for Mobile Communications (GSM) systems within radar waveform design is provided. LPR radars focus on deceiving electronic support (ES) receivers by selecting waveforms which emulate the waveforms of communication transmitters and thus provide an additional mechanism to achieve covert operation. The advantages and drawbacks of different levels of LPR are analysed from both the radar and ES-receiver perspectives. Some LPR techniques have only a minor effect on radar performance while requiring vastly more complex ES systems to address, and vice versa. This means that both radar and ES systems must be considered when evaluating LPR techniques.

A Coherence-Based Algorithm for Optimizing Rank-1 Grassmannian Codebooks

Infrared (IR) guided missiles remain a threat to both military and civilian aircraft, and as such, the development of effective countermeasures against this threat remains vital. A simulation has been developed to assess the effectiveness of a jammer signal against a conical-scan seeker by testing critical jammer parameters. The critical parameters of a jammer signal are the jam-to-signal (J/S) ratio, the jammer frequency and the jammer duty cycle. It was found that the most effective jammer signal is one with a modulated envelope.