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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluation of CNN in ESM Data Classification by Perspective of  Military Utility / Utvärdering av convolutional neural networks för ESM-dataklassifikation genom perspektivet av militär nytta

Johansson, Jimmy January 2020 (has links)
Modern society has seen an increase in automation using AI in a variety of applications. To keep up with recent development, it is therefore logical to investigate the application of AI programs to military tasks. The great advantage with automation lies in the possible increase in efficiency and possible relocation of resources of personnel to other tasks. Therefore, this study aims to evaluate the use of Convolutional Neural Networks (CNN) in classification of communication and radar emitters based on collected Electronic Support Measures (ESM) data and to estimate to what extent human analysts could be replaced. The evaluation was performed by applying the concept of military Utility as a framework for evaluation with the addition of Technology Readiness Level (TRL) to survey how far the technology has developed. Data was collected using two methods: Firstly, through a literature review of research done on the application of CNNs in classifying information such as spectrograms and images. Secondly, by interviewing a subject matter expert from SAAB, who mainly helped estimate the TRL of the technology’s components. The study found that CNN appears suitable to apply on the proposed task and that the program could potentially replace human analysts to a great extent, at least when doing routine classifications. Full automation seems unlikely as analysts would be required with more challenging classifications, especially those outside the range of the training data used in teaching the CNN. Finally, challenges involved with deep learning programs inherent structure, demands and application to military tasks are discussed and subjects for future research are proposed. / Det moderna samhället har sett en ökad automatisering med AI i en mängd olika applikationer och för att hålla jämna steg med den senaste utvecklingen är det därför logiskt att undersöka tillämpningen av AI-program på militära uppgifter. Den stora fördelen med automatisering ligger i den möjliga ökningen av effektivitet och möjlig flytt av personalresurser till andra uppgifter. Därför syftar denna studie till att utvärdera användningen av convolutional neural networks (CNN) vid klassificering av kommunikations- och radarsändare baserat på insamlade data från elektronisk stödverksamhet (sv. ES motsvara eng. ESM) och att uppskatta i vilken utsträckning mänskliga analytiker kan ersättas. Utvärderingen genomfördes genom att använda konceptet militär nytta som ett ramverk för utvärdering med tillägg av technology readiness level (TRL) för att kartlägga hur långt tekniken har utvecklats. Data samlades in med två metoder: För det första genom en litteraturöversikt av forskning som gjorts om tillämpningen av CNN för att klassificera information såsom spektrogram och bilder. För det andra genom att intervjua en ämnesexpert från SAAB, som främst hjälpte till att uppskatta TRL för teknikens komponenter. Studien fann att CNN verkar lämplig att använda till den föreslagna uppgiften och att programmet potentiellt skulle kunna ersätta mänskliga analytiker i stor utsträckning, åtminstone for rutinklassificeringar. En fullständig automatisering verkar osannolik eftersom analytiker skulle krävas med mer utmanande klassificeringar, särskilt de som ligger utanför utbildningsdata som används för att lära upp programmet. Slutligen diskuteras utmaningar kopplade till djup-inlärningsprogrammens struktur, krav och tillämpning på militära uppgifter samt att ämnen för framtida forskning föreslås.
2

Dataset Drift in Radar Warning Receivers : Out-of-Distribution Detection for Radar Emitter Classification using an RNN-based Deep Ensemble

Coleman, Kevin January 2023 (has links)
Changes to the signal environment of a radar warning receiver (RWR) over time through dataset drift can negatively affect a machine learning (ML) model, deployed for radar emitter classification (REC). The training data comes from a simulator at Saab AB, in the form of pulsed radar in a time-series. In order to investigate this phenomenon on a neural network (NN), this study first implements an underlying classifier (UC) in the form of a deep ensemble (DE), where each ensemble member consists of an NN with two independently trained bidirectional LSTM channels for each of the signal features pulse repetition interval (PRI), pulse width (PW) and carrier frequency (CF). From tests, the UC performs best for REC when using all three features. Because dataset drift can be treated as detecting out-of-distribution (OOD) samples over time, the aim is to reduce NN overconfidence on data from unseen radar emitters in order to enable OOD detection. The method estimates uncertainty with predictive entropy and classifies samples reaching an entropy larger than a threshold as OOD. In the first set of tests, OOD is defined from holding out one feature modulation from the training dataset, and choosing this as the only modulation in the OOD dataset used during testing. With this definition, Stagger and Jitter are most difficult to detect as OOD. Moreover, using DEs with 6 ensemble members and implementing LogitNorm to the architecture improves the OOD detection performance. Furthermore, the OOD detection method performs well for up to 300 emitter classes and predictive entropy outperforms the baseline for almost all tests. Finally, the model performs worse when OOD is simply defined as signals from unseen emitters, because of a precision decrease. In conclusion, the implemented changes managed to reduce the overconfidence for this particular NN, and improve OOD detection for REC.

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