Research On Wideband Angle Tracking Techniques For The High-speed Satellite-ground Data Link

With increasing demand in the transmission speed, which may be as high as several hundred megabits even to gigabit, the bandwidth also becomes larger and larger, so that high transmission rate has become a trend for satellite-ground data link. For the sake of reducing the volume and weight of the satellite-borne equipment, the transmission link needs to rid of any additional beacon signal, which means that the receiving system on the ground must be able to track the downlink wide-band signal directly. So it is an important application research issue for the high-speed satellite-ground data link how to make the receiving system to track the target with high sensibility and high accuracy in angle measurement.This paper mainly discusses the wideband angle tracking and measuring techniques, as well as the applications to practical engineering in the high-speed satellite-ground data link. During the development of the wideband tracking receiver, this thesis proposes a general scheme for the tracking equipment in a receiver. Basing on the theoretical analysis and deduction about angle tracking principle, the thesis proposes a small-part-energy angle tracking method, which aims at demodulating the angle error information of low frequency with only a part of the energy spectrum of the wideband signal.The tracking system is implemented by means of IF digitizing technique, where the single channel QPSK modulation signal, with a bandwidth of 12MHz and IF of 70MHz, is processed via band-pass sampling and digital down-converting. The author has designed the main units of the system; deduced the principle of the digital signal processing units; tested the performance and validated the feasibility of the system by computer simulation experiments.Finally, some suggestions about further research in this area is put forward to combine with practical use in the engineering applications.