Calibration of the OLFAR space-based radio telescope using an alternating least squares approach

摘要

Radio astronomy below 30 MHz has never been properly performed because the ionosphere inhibits this on Earth. The Orbiting Low-Frequency Antennas for Radio Astronomy (OLFAR) project aims to build a radio telescope consisting of 50 or more nano-satellites in space, forming a swarm-like array. The observational antenna systems need to be calibrated to successfully detect astronomical signals. However, a satellite swarm presents a unique calibration challenge, which is outlined in this paper. An approach is proposed for the calibration of several important system parameters, based on alternating least squares (ALS). In the proposed method, polarization is taken into account without the common simplifications, such as only considering fully linear polarization, and a good convergence rate is achieved. For validation, Monte Carlo simulations are compared with the Cramer-Rao bound.