This master thesis investigates different approaches to data compression on common types of signals in the context of localization by estimating time difference of arrival (TDOA). The thesis includes evaluation of the compression schemes using recorded data, collected as part of the thesis work. This evaluation shows that compression is possible while preserving localization accuracy. The recorded data is backed up with more extensive simulations using a free space propagation model without attenuation. The signals investigated are flat spectrum signals, signals using phase-shift keying and single side band speech signals. Signals with low bandwidth are given precedence over high bandwidth signals, since they require more data in order to get an accurate localization estimate. The compression methods used are transform based schemes. The transforms utilized are the Karhunen-Loéve transform and the discrete Fourier transform. Different approaches for quantization of the transform components are examined, one of them being zonal sampling. Localization is performed in the Fourier domain by calculating the steered response power from the cross-spectral density matrix. The simulations are performed in Matlab using three recording nodes in a symmetrical geometry. The performance of localization accuracy is compared with the Cramér-Rao bound for flat spectrum signals using the standard deviation of the localization error from the compressed signals.

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 Engineering / unrestricted

In this report metrics for jamming resistance and radar performance of waveform sets are described and developed, and different sets of waveforms are optimized, evaluated and compared. It is shown that without additional processing or PRI jitter, waveform sets can reach jamming resistance a few dB worse than what is provided by PRI jitter alone, and together with PRI jitter a few dB better. Waveforms with better jamming resistance tend to have worse range sidelobes and Doppler tolerance, but show less structure in their spectrograms, suggesting better LPI properties. The Doppler tolerance metric is new, as well as the comparative analysis of waveform sets on multiple metrics including jamming resistance. / Radar är fundamentalt i modern krigsföring. Med en radar kan man avfyra vapen från säkra avstånd och med precision mäta in mål. En radarstörare har som mål att förhindra en radar från att mäta in sitt mål. Då radarn fungerar genom att sända ut specifikt modulerade radiovågspulser och lyssna efter ekot från omgivningen kan störaren förhindra detta genom att antingen sända mycket starkt brus, eller genom att sända radiovågspulser med samma specifika modulation. Den senare metoden kallas för DRFM-störning, där förkortningen står för Digitalt RadioFrekvens-Minne, vilket antyder att störaren kan minnas radarns modulation och själv använda den. Om radarn använder en ny modulation (eng: waveform) för varje puls kan störaren inte använda modulationen den minns från förra pulsen utan måste vänta på att nästa puls träffar den innan den kan repetera pulsen, vilket begränsar dess störförmåga. Denna rapport tänker sig att radarn har en begränsad uppsättning av modulationer att byta mellan, och undersöker olika sådana uppsättningar och bedömer och jämför dem på olika mått av radarprestanda och störtålighet. Radioprestandamåtten inkluderar hur mycket förstärkning och hur fin upplösning man får av modulationen, hur väl modulationen kan hantera mycket snabba mål, och hur stora "sidolober" som uppstår runt starka mål. Sidolobsfenomenet är jämförbart med det optiska fenomenet där små men ljusstarka saker på natten kan se ut att ha en ljus halo eller ljusa utstrålningar runt sig. Störtålighetsmåtten kvantifierar hur distinkta de olika modulationerna i radarns uppsättning är, och på så vis hur väl radarn kan urskilja en modulation från de andra, tillsammans med hur liten sannolikheten är att störaren lyckas välja just den modulation vi kommer använda till nästa puls. Resultaten visar att metoden av modulationsbyten kan ge nästan lika stor störtålighet som en välkänd metod, PRI-jitter, ger själv och något högre i kombination med den metoden. Bättre störtålighet visas gå hand i hand med sämre mått på radarprestanda, men mindre strukturerade spektrogram vilket antyder att de kan vara svårare att upptäckas av radarspanare. Försämringen i måtten på radarprestanda innebär inte nödvändigtvis en lika stor försämring i faktisk radarprestanda, då sidoloberna tar an en brusartad karaktär vilket leder till praktiska fördelar gentemot de vanliga fixa sidoloberna.

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Approved for public release, distribution is unlimited / This thesis will address the planned configuration of Lockheed Martin's Flight Zero, Module Spiral Alpha Littoral Combat Ship (LCS) and the ongoing development of the SPARTAN SCOUT, one of the Navy's Unmanned Surface Vessels (USV). Technology currently available as well as developmental technologies will be recommended for implementation in order to make the LCS and SCOUT assets to Information Operations (IO) objectives. Specific technology will include Outboard, TARBS, HPM, Loudspeakers, LRAD and Air Magnet. This thesis will include an evaluation of the current policy for authorizing Information Operations missions, specifically in the areas of Psychological Operations (PSYOP) and Electronic Warfare (EW). / Lieutenant, United States Navy

Approved for public release; distribution in unlimited. / This is a study of abnormal refractive layer occurrence over the Amazon region and possible effects on radar and ESM systems, ground or airborne based. Climatologic data from three stations in that region are analyzed using computations from the Global Tropospheric Experiment (GTE), soundings and satellite imagery. The GTE data provide monthly occurrences and seasonality of atmospheric ducts and superrefractive layers. Further, individual soundings from the March-June 2003 period and the Advanced Refractive Effects Prediction Systems (AREPS) 2.1 software are used in a case study that analyzed these layers and, in addition, subrefractive and multiple layers. Selected soundings were used in simulations to explain the effects of different types of abnormal layers on the electromagnetic propagation. Although abnormal layers did not affect ground systems, airborne ones were. For radar, a region with low or no detection is created when an abnormal layer refracts the electromagnetic energy upwards or downwards. Some combinations of multiple layers may cause effects even stronger. It is concluded that knowledge of the abnormal layers occurrence is important for operations in the Amazon region. Further, airborne radar platforms should measure local refractive conditions, if possible. A comprehensive study in time and space is recommended to provide forecasting. / Lieutenant Colonel, Brazilian Air Force

UAV:er används frekvent i samhället och med detta har den kommersiella marknaden växt. Därför är det rimligt att de används i större utsträckning i konflikter, vilket innebär att konflikter där båda parter har UAV:er som kan klassas som relativt högteknologiska möts blir troligare. Ukraina och Rysslands användande av UAV i Ukraina kan räknas som denna typ av konflikt.  I uppsatsen är det UAV:er av den militära typen som diskuteras. Skillnaden mellan dessa och civila typer är framförallt räckvidd, flygtid och kvalitén på sensorerna.För att undersöka hur UAV:er nyttjas och taktiseras med i denna typ av konflikter har följande frågeställning använts: Hur påverkas nyttjandet av UAV:er i en konflikt mellan två högteknologiska motståndare?Genom att analysera beslutsprocessen med hjälp av OODA-loopen och bekämpningskedjan har författaren kunnat dra följande slutsatser om nyttjandet i denna typ av konflikt. Uppsatsen är genomförd som en fallstudie där metoderna kvalitativ textanalys och intervju använts Slutsatsen är att den multiplikator som UAV varit i Ukraina visar på att de kommer fortsätta användas i framtida konflikter. Trots att telekrig varit aktivt mot just UAV:erna och att de saknar motmedel mot störningen har de fortsatt att nyttjas, den multiplikatoreffekt de bidrar med kan motiveras stridsekonomiskt och väger tyngre än de problem som störningen innebär. / UAV: s are in more frequent use as a result of a growing commercial market. This increases the probability of UAV: s in conflicts. This means that conflicts where both sides have access to UAV: s that are relatively high-tech becomes more likely. Ukraine and Russia’s use of UAV: s in Ukraine can be described as this kind of conflict. In this paper it is primarily military UAV: s that are discussed. The difference between these and their civilian counterparts are range, flight time and the quality of the sensors. In order to understand how the use of UAV: s is being affected, the following question needs to be answered.  How is the use of UAV: s affected in a conflict between two high-tech opponents? This was answered by analysing the decision-making process using the OODA loop and the kill chain. The paper is a case study which uses qualitative text analysis and an interview.The conclusion of this paper is that UAV: s has acted as a force multiplier in Ukraine and they will be used in future conflicts. Despite the electronic warfare against the UAV: s and the fact that they are missing systems for counteracting the disturbance both sides continue to use UAV: s. The force multiplier that is gained from using UAV: s is justified from a battle economic standpoint despite being hindered by electronic warfare.

Modern applications are required to handle and communicate an increasing amount of data. Meanwhile, distributed systems containing multiple computationally weak components becomes more common, resulting in a problematic situation. Choosing among communication strategies, used for delivering message between entities, therefore becomes crucial in order to efficiently utilize available resources. Systems where identical data is delivered to many recipients are common nowadays, but may apply an underlying communication strategy based on direct interaction between sender and receiver which is insufficient. Multicasting refers to a technique for group communication where messages can be distributed to participating nodes in a single transmission. This technique is developed to circumvent the problem of high workload on sender side and redundant traffic in the network, and constitutes the focus for this thesis. Within the area of Electronic Warfare and self-protection systems, time constitutes a critical aspect in order to provide relevant information for decision making. Self-protection systems developed by Saab, used in military aircrafts, must provide situational awareness to guarantee that correct decisions can be made at the right time. With more advanced systems, where the amount of data needed to be transmitted increases, the need of fast communication is essential to achieve quality of service. This thesis investigates how the deployment of multicast, in a distributed data-intensive system, could prepare a system for increased data exchange. The result is a communication design which allows for the system to distribute messages to a group of receivers with less effort from the sender and with reduced redundant traffic transferred over the same link. Comparative measurements are conducted between the new implementation and the old system. The result of the evaluation shows that the multicast solution both can decrease the time for message handling as well as the workload on endpoints significantly. / Nutidens applikationer måste kunna hantera och kommunicera en ökad datamängd. Samtidigt har distribuerade system bestående av många beräkningsmässigt svaga enheter blivit allt mer vanligt, vilket är problematiskt. Valet av kommunikationsstrategi, för att leverera data mellan enheter i ett system, är därför av stor betydelse för att uppnå effektivt utnyttjande av tillgängliga resurser. System där identisk information ska distribueras till flertalet mottagare är vanligt förekommande idag. Den underliggande kommunikationsstrategin som används kan dock baseras på direkt interaktion mellan sändare och mottagare vilket är ineffektivt. Multicast (Flersändning) syftar till ett samlingsbegrepp inom datorkommunikation baserat på gruppsändning av information. Denna teknik är utvecklad för att kringgå problematiken med hög belastning på sändarsidan och dessutom minska belastningen på nätverket, och utgör fokus för detta arbete. Inom telekrigföring och självskyddssystem utgör tiden en betydande faktor för att kunna tillhandahålla relevant information som kan stödja beslutsfattning. För självskyddssystem utvecklade av Saab, vilka används i militärflygplan, är situationsmedvetenhet av stor betydelse då det möjliggör för att korrekta beslut kan tas vid rätt tidpunkt. Genom utvecklingen av mer avancerade system, där mängden meddelanden som måste passera genom nätverket ökar, tillkommer höga krav på snabb kommunikation för att kunna åstadkomma kvalité. Denna uppsatsrapport undersöker hur införandet av multicast, i ett dataintensivt distribuerat system, kan förbereda ett system för ökat datautbyte. Arbetet har resulterat i en kommunikationsdesign som gör det möjligt för systemet att distribuera meddelanden till grupp av mottagare med minskad belastning på sändarsidan och mindre redundant trafik på de utgående länkarna. Jämförandet mätningar har gjorts mellan den nya implementationen och det gamla systemet. Resultaten visar att multicast-lösningen både kan reducera tiden för meddelande hantering samt belastningen på ändnoder avsevärt.

This Master’s Thesis is an evaluation of the software Xilinx System Generator (XSG) and blockset for Matlab. XSG is a module to simulink developed by Xilinx in order to generate VHDL code directly from functions implemented in Matlab. The evaluation was made at Saab Avionics AB in Järfälla, north of Stockholm. In order to investigate the performance of this new module XSG to simulink, a model of a frequency estimator often used in digital radar receivers were implemented in Matlab using XSG. Engineers working at SAAB Avionics implemented the same application directly in VHDL, without using Matlab and the XSG. After generating code the results were synthesised, analysed and compared. The frequency estimator basically contains an FFT, a windowing function and a sorting algorithm used to enable analyse of two real signals simultaneously. There were however problems during generation of the VHDL code and the model had to be broken into smaller parts containing only a 16-point FFT. The results of comparison in this report are based on models containing only this 16-point FFT and they show a small advantage for the System Generator according to the resource usage report generated during synthesis. Designing models for generation using Xilinx Blockset can create a lot of wiring between components. The reason for this is that the System Generator and Xilinx Blockset today is a new tool, not completely developed. There are many components found in simulink, Matlab that could not be found in Xilinx Blockset, this is however being improved. Another problem is long time for simulation and errors during generation. My opinion is that when used for smaller systems and with further development the System Generator can be a useful facility in designing digital electronics.

<p>This Master’s Thesis is an evaluation of the software Xilinx System Generator (XSG) and blockset for Matlab. XSG is a module to simulink developed by Xilinx in order to generate VHDL code directly from functions implemented in Matlab. The evaluation was made at Saab Avionics AB in Järfälla, north of Stockholm. </p><p>In order to investigate the performance of this new module XSG to simulink, a model of a frequency estimator often used in digital radar receivers were implemented in Matlab using XSG. Engineers working at SAAB Avionics implemented the same application directly in VHDL, without using Matlab and the XSG. After generating code the results were synthesised, analysed and compared. </p><p>The frequency estimator basically contains an FFT, a windowing function and a sorting algorithm used to enable analyse of two real signals simultaneously. There were however problems during generation of the VHDL code and the model had to be broken into smaller parts containing only a 16-point FFT. The results of comparison in this report are based on models containing only this 16-point FFT and they show a small advantage for the System Generator according to the resource usage report generated during synthesis. </p><p>Designing models for generation using Xilinx Blockset can create a lot of wiring between components. The reason for this is that the System Generator and Xilinx Blockset today is a new tool, not completely developed. There are many components found in simulink, Matlab that could not be found in Xilinx Blockset, this is however being improved. Another problem is long time for simulation and errors during generation. </p><p>My opinion is that when used for smaller systems and with further development the System Generator can be a useful facility in designing digital electronics.</p>