The use of spread spectrum signals has increased dramatically in military applications. Finding methods for detecting and positioning of these signals have become interesting research areas for signal intelligence purposes. One method is to measure the time difference of arrival (TDOA) that occurs when two receivers are synchronous and spatially separated. Based on the TDOA-technique an audio-demonstrator has been developed and implemented. This report describes the theory for how sound received in microphones can be used to extract information about the transmitter’s position from the measured time difference. The technique has been implemented and tested in a non-silencing room where sound from a loudspeaker has been recorded into MATLAB through the use of microphones. By correlating the received signals, an estimation of the time difference can be made. A hyperbolic function represents all possible transmitter positions for the given time difference. With three of more receivers a single position can be estimated. With an accuracy within a couple of hundreds of a degree, a direction can be estimated with simulated signals for a given SNR (usually 25dB) or a position within a few centimetres when the transmitter is a couple of meters away. Tests with real audio signals show less satisfying results. The position can at best be estimated with an accuracy of 5% of the distance to the receiver when the microphones are spread out 0.7m apart. The performance of the audio-demonstrator can be improved by using better methods for finding the points of intersection between hyperbolas and by weighting the estimated time differences.

<p>The use of spread spectrum signals has increased dramatically in military applications. Finding methods for detecting and positioning of these signals have become interesting research areas for signal intelligence purposes. One method is to measure the time difference of arrival (TDOA) that occurs when two receivers are synchronous and spatially separated. Based on the TDOA-technique an audio-demonstrator has been developed and implemented. This report describes the theory for how sound received in microphones can be used to extract information about the transmitter’s position from the measured time difference. The technique has been implemented and tested in a non-silencing room where sound from a loudspeaker has been recorded into MATLAB through the use of microphones. By correlating the received signals, an estimation of the time difference can be made. A hyperbolic function represents all possible transmitter positions for the given time difference. With three of more receivers a single position can be estimated. With an accuracy within a couple of hundreds of a degree, a direction can be estimated with simulated signals for a given SNR (usually 25dB) or a position within a few centimetres when the transmitter is a couple of meters away. Tests with real audio signals show less satisfying results. The position can at best be estimated with an accuracy of 5% of the distance to the receiver when the microphones are spread out 0.7m apart. The performance of the audio-demonstrator can be improved by using better methods for finding the points of intersection between hyperbolas and by weighting the estimated time differences.</p>

I arbetet undersöks, utifrån ett telekrigperspektiv med inriktning från ett signalspaningshot, riskerna med nyttjandet av smarta mobiltelefoner i svenska markförband. Undersökningen baseras på ett fiktivt scenario i en nationell kontext och utgår ifrån två aktörer där ena aktören nyttjar smarta mobiltelefoner och andra aktören nyttjar högteknologiska telekrigsystem för att exploatera dess risker. Utifrån, i arbetet framtagna riskindikatorer, skapas olika händelseutvecklingar vilka undersöks utifrån en kvalitativ metod med inslag av kvantitativa beräkningar. Resultatet påvisar att smarta mobiltelefoner, nyttjade inom ramen för svenska markförband, riskerar utsätta såväl individer som hela förband för risker. Riskerna vilka undersöks är avlyssning, lägesbestämning och avslöjande av information genom mobiltelefonernas GNSS-förmåga och geotaggningsfunktioner. Användning av smarta mobiltelefoner riskerar således oavsiktligt röja information varför nyttjandet kräver förståelse för de risker dessa genererar. Riskerna kan inte undvikas varför nyttan med smarta mobiltelefoner måste vägas mot risken i varje situation. / In this thesis, the risks of smartphones in Swedish land forces are analysed from anElectronic Warfare perspective, focusing on Signals Intelligence. The analysis is based on a fictitious scenario in a national context involving two differentactors. One actor uses smartphones and the other actor uses high technology ElectronicWarfare systems to exploit the phones. Based on risk indicators developed in the thesis, twodifferent cases are created, which are then analysed using a qualitative method with elementsof quantitative calculations. The results reveal that smartphones, used in Swedish land forces, put both individuals andunits at risk. The risks, analysed, are interception, location and revealing information fromthe phone’s Global Navigation Satellite System geotagging and functions. Therefore, the useof smartphones might unintentionally reveal information. Consequently, the use ofsmartphones requires an understanding of the risks generated. It is not possible to avoid risks,so the benefit of using smartphones must be weighed against the risk in each situation.