Research On Signal Processing Technology Of GNSS Receiver

Global Navigation Satellite System (GNSS) can provide accurate position, velocity and timing services system all-weather, real-time. With the GNSS widely used in the military and civilian fields and the environments becoming more complex, the signal becomes weaker and susceptible to interference, especially in complex environments such as indoor, forest and tunnels, etc. In that case, the traditional GNSS receiver may not work. Therefore, the study of the anti-jamming of GNSS receiver and weak signal acquisition technologies has get more attention and it has important theory research signification and utility value.The main problems of GNSS receiver are the interference which influences signal quality and the requirement of receiver sensitivity increasingly high. Thus, this article elaborates the architecture of GNSS and principle of GNSS receiver. At the same time, the interference detection methods and acquisition algorithms have studied. The main work and conclusions are as follows:For the situation that GNSS signal is easily interfered and the signal quality can seriously get worse in complex environments, several time-frequency analysis methods have been discussed, then establishes sweep interference model, proposed an interference detection method based on fractional Fourier transform. The main ideal of this method is making the continuous fractional Fourier translation of the GNSS signal to acquire the fractional power by searching two-dimensional spectral peak, then do fractional Fourier transform and detection the interference. The proposed method based on fractional Fourier transform not only overcomes the shortcomings of other time-frequency methods, but also reduces the amount of calculation, can detect the interference effectively.By utilizing the signal data and pilot channels, joint data/pilot channels combining methods have been proposed in order to improve the sensitivity of the GNSS receiver. The proposed methods make full use of the power of the data and pilot channels, provide an excellent performance than traditional acquisition methods and improve the sensitivity of GNSS receiver acquisition significantly in weak signal environments.Simulation results demonstrate that the fractional Fourier transform method has better detection performance compared to short time Fourier transform and Wigner-Wile Distribution methods. Differential channels combining technology provide a better performance, especially the differential coherent channel acquisition technology, is more suitable for weak signal environments acquisition.