| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 103 === In this thesis, we propose a blind direction of arrival (DOA) estimation of a frequency hopping signal source without a priori information of its hopping pattern.
The DOA estimation can be divided into 3 stages, including frequency hopping signal detection, preliminary DOA estimation, and accurate DOA estimation. First, we use low complexity short-time Fourier transform (STFT) time-frequency analysis to detect the hopping pattern of a frequency hopping signal, and then applying the estimated hopping pattern to a quick pseudo Doppler direction finder to perform the preliminary DOA estimation. Finally, we substitute the preliminary estimation result into a maximum likelihood (ML) scheme as the initial value and obtain the accurate estimation result.
Computer simulations are used to verify the performance of the hybrid DOA estimation, where Bluetooth signals generated by Simulink software are used as sources. After comparing the maximum likelihood estimation with or without pseudo Doppler scheme, the results show that hybrid DOA estimation not only can accelerate the convergence speed of maximum likelihood estimation, but also prevent the maximum likelihood estimation from converging to a local minimum problem. Consequently, the hybrid DOA estimation can effectively improve the accuracy of DOA estimation of a frequency hopping signal.
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