Simulations of Adaptive Filters of Antenna Systems Based on the Matlab/Simulink Tools

In order to make signals received by radio-telescope antenna systems more clearly recognizable, i.e. with system noise and electromagnetic interferences reduced to desired levels, we design a type of adaptive filters and numerically simulate their performances using the powerful Matlab/Simulink tools. Our adaptive filters are to meet the special requirements on radio-astronomy observations and deep-space explorations (of the Moon and Mars) at the Nanshan Station of the Xinjiang Astronomical Observatory, Chinese Academy of Sciences. In an earlier section of this paper we present signals from the pulsars 1910+0728 and 1913-0440 (Liu Qi, private communication), which serve as reference signals for testing the filters. We write an algorithm in a Matlab M-file realizing the adaptive filtering. The file is easily understandable and allows other people to study. Our simulation tests with the pulsar signals show that the filters can effectively reduce the noise. In addition, we use the Simulink in the Matlab for modeling and simulating antenna systems (including the filtering). By extensively changing the order and the iteration step size of a modeled filter, we find the optimal parameters for our adaptive filter: an order of eight and a step size of 0.005. In the process, we have also verified that filters of this type can effectively restore profiles of received signals and minimize errors while fast processing signals. The simulation results and subsequent analyses of these (particularly the results with the Simulink) show that our adaptive filters can practically result in fine outputs and meet the needs of radio astronomy. With the rapid development of radio astronomy in China and the progress of building the 110m radio telescope in Xinjiang, filters as ours will be widely used for deep-space explorations and astronomical observations.