Studying On Narrowband Interference Suppression In LEO Satellite Spread Spectrum Communication Systems

Micro-satellite technology and system has a good application outlook in communication, remote sensing, science research, technique demonstration, interstellar exploration, education, and so on. The availability of low orbit satellite spread-spectrum communications is impacted by the complicated radio environment in China and Southeast Asia. To improve the availability of satellite spread-spectrum communication systems, the radio environment in China is surveyed by a certain low orbit satellite. The result indicated that the radio interference of UHF is mainly dominated by the narrowband interference. Where, the narrowband interference is defined as the signal which bandwidth is less than the bandwidth of the received spread-spectrum signal very much, including mono-tone, multi-tone, pulse Cosine Wave interference and some others.In this dissertation, some methods in time/frequency-domain for narrowband interference suppression in the low orbit satellite spread spectrum communication are studied. Some modified algorithms are put forward as follow:1 , A new non-linear LTJ filter is presented in time-domain and a developed simple non-linear function, which almost has the same error performance for narrowband interference, is used to modify the LTJ filter. On the other hand, the convergence and error performance of the lattice and LMS parts in the modified filter are researched and the expression of filtered error power by theory is concluded in this paper to analyze the performance of interference suppression quantificationally.2, A simplified algorithm for estimating threshold between interference and others and attenuating the interference magnitude linearly are advanced in frequency-domain. These methods can suppress the narrowband interference...