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SAR Image Formation with Embedded QPSK Communications in LFM Guardbands and UAV Antenna Characterization
[Technical Report, Master's Thesis]
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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Synthetic aperture radar SAR imaging with the use of a small-sized unmanned aerial vehicle UAV isa fairly recent and very promising application. There are two main thrusts in this thesis a SAR imaging with radar-communications waveform, and b antenna characterizations with a UAV. Quadrature phase shift keying QPSK modulation is embedded to transmit data to a communications receiver via the guard bands of a linear frequency modulated LFM signal for SAR. Images are formed with the LFM-QPSK combined signal i.e., there is no need to filter out the communications signal in the radar receiver. We vary signal-to-noise power ratio and LFM to communications bandwidth ratio and investigate how each parameter affects the SAR images generated. We also look at the effect of shifting the communications carriers away from the LFM spectrum on the SAR image. The next step in developing and fielding a system is selecting an antenna and performing a pattern characterization with a UAV via radio frequency transmission to ground receiver. Antenna characterization is performed by transmitting a continuous wave signal from a UAV and measuring received power from a seven-element Yagi antenna on the ground.
[A, Approved For Public Release]