Research On Satellite Navigation Anti-jamming Receiving System

Along with the rapid development of modern technology, satellite navigation, as a new satellite-based radio navigation method, is widely used in military field. However, problems of weak signals and vulnerable to interference of satellite navigation systems are becoming more and more serious, thus it is needed to study the satellite navigation receiving system with anti-jamming ability.This paper systematically summarizes the present situation of research on the anti-jamming technology for satellite navigation domestic and overseas, analyzes and discusses the advantages and disadvantages of different implementations.In allusion to characteristics of the satellite navigation signals, the Least Mean-Square (LMS) algorithm and the Recursive Least Squares (RLS) algorithm are applied to satellite navigation receiving systems in this paper, and the effects are simulated and analyzed that the different snapshot numbers and different ratio of jamming to noise impact on the null steering produced by LMS and RLS algorithms at the directions of interferences. Monte-Carlo experiments are used to analyze the interference suppression performances under the conditions of array mutual coupling exists or the amplitudes and phases of channels are inconsistent. The algorithm complexity, convergence and anti-jamming performance of these two algorithms are analyzed and compared, which provide a theoretical basis and design reference for designing satellite navigation anti-jamming systems.Based on summarized the structure of GPS signal and its frequency characteristics, in this paper, the effects that interferences impact on the GPS receiving system are analyzed. A GPS anti-jamming receiving system based on the software radio technology is proposed, and the sensitivity, noise figure, dynamic range required by the system is analyzed. The frequency selectivity, gain budget, noise figure budget of the RF module is simulated, and RF system architecture suitable for this system is chosen. The relationship between the A/D conversion bits and sampling frequency in the signal processing module and the system performance is analyzed, and the effects of the quantization bits in the signal processing module impact on the system anti-jamming performance are simulated and analyzed. And the interference sources and sensitivity sources in the electromagnetic compatibility of system are analyzed.On the basis of theoretical analysis and simulation, a mini microstrip antenna array of GPS and RF modules are designed in this paper, which include low noise amplifiers, mixers, intermediate frequency amplifiers, automatic gain amplifiers, and frequency synthesizers. High performance signal processing modules are designed, of which two improved designs of miniaturization and low power are made. The anti-jamming algorithm procedures in hardware are achieved. Electromagnetic compatible GPS anti-jamming receiving systems are designed and implemented, and system tests are made.For multi-mode satellite navigation, the signal characteristics and frequency characteristics of various modes of satellite navigation systems are summarized in this paper. Two system structures of multi-mode anti-jamming receiving systems are proposed. Sub-modules of anti-jamming signal processing for GPS/GLONASS are designed. The DDS frequency sources with multiple outputs are designed for multi-mode satellite navigation anti-jamming receiving systems.As one of the key components of multi-mode satellite navigation anti-jamming systems, dual-frequency/multi-frequency power dividers are researched and designed in this paper. For dual-frequency power dividers, compact planar dual-frequency two way and three way power dividers are proposed, two planar dual-frequency power divider using umbrella-shaped resonator is presented, the structure of them are analyzed, some of the designed equations are deduced to obtained the parameters. In order to certify the effectiveness, the proposed power dividers are fabricated. The theoretical and simulated are in good agreement with measured results. For tri-frequency power divider, a coupled microstrip two way power divider and a three way power divider are presented in this paper. The equations of design parameters are given. The proposed power dividers are fabricated.The simulated results are in good agreement with measured results, which shows good RF performances are achieved.