Estimation of the direction of arrival of signals from Nano-satellites

This book presents an investigation of various signal processing algorithms for estimating the direction of arrival (DOA) of an HF radio signal from a CubeSat in space to ground. The DOA of the signal is expressed in terms of two angles azimuth and elevation. The azimuth and elevation angles are derived from the phase differences between signals observed by an array of three crossed-loop elements arranged in an L-shaped configuration. The DOA of the signal will be determined by processing the signals received by the array. We investigate and compare four algorithms. These algorithms are Zero Crossing (ZC), Cross Correlation (CC), Fast Fourier transform (FFT) and Cross Power Spectral Density (CPSD). These algorithms are tested using simulated signals. The algorithms were implemented in MATLAB and a comparison of two figures of merit: accuracy and speed was conducted. The simulations indicate that the FFT and CPSD algorithms outperform the CC and ZC algorithms in terms of accuracy. However, the FFT algorithm was selected as an optimum algorithm due to it is better computation time.