Analysis of an Optimisation-Based De-Pointing Measurement Method for LEO Satellite Terminal Characterisation

The next generation on-the-move LEO satellite communication terminals require new testing methods to ensure their performance and pointing accuracy remains consistent while under motion. This paper presents and analyses a method for measuring the pointing angle of an electronically steered satellite communication user terminal in real time. The method uses an array of measurement probes around the target direction to sample the power of the antenna array pattern. A local optimiser is used to match a gaussian function to the sampled amplitudes. Analysis of this algorithm is presented to demonstrate how the range and density of the measurement array can impact the accuracy of the system for antennas of various beamwidths. The algorithm is found to provide accuracy within 0.05° for antenna beamwidths of 0.6° to 25° where the measurement array covers an angular range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 5^{\circ}$</tex> around the desired pointing direction and has an element separation of 0.5°.