The global navigation satellite system is a high-precision radio navigation system based on artificial satellites. Among the factors affecting the positioning accuracy of the navigation satellite system, the multipath signal is the most significant and challenging to eliminate. Furthermore, the multipath environment of the receiver is also becoming more complex, and it seriously threatens the measurement accuracy and stability of the receiver. The multipath mitigation technology is also continuously improved and developed in practical application. This paper firstly introduces the concept and characteristics of multipath signals, and summarizes the influence of multipath signals on navigation satellite systems from two aspects of code tracking loop and carrier tracking loop. Furthermore, the existing multipath mitigation technology is summarized in four stages: signal system design, antenna design, baseband signal processing, and navigation data processing. Finally, according to the summary of the existing technology and the new demand, the future development direction of multipath suppression technology is prospected.

Power-inversion (PI) adaptive arrays are widely used in Global Navigation Satellite System (GNSS) receivers for interference mitigation. The effects of element patterns on the performance of PI adaptive arrays are investigated in this paper. To this end, the performance of adaptive arrays is investigated by Monte Carlo simulations, using CST Microwave Studio (Dassault Systems, Vélizy-Villacoublay, France) to calculate the radiation patterns of circular microstrip elements which are used to compute the adaptive weight and the adaptive array gain. It is shown that the performance of PI adaptive arrays is mainly dependent on the gain pattern of the reference antenna element rather than the non-reference elements because the algorithm essentially pushes the elements into an unequal position. Furthermore, the results show that the impact of mutual coupling on the performance of the antenna array can be associated with the radiation patterns of the reference element, which is helpful in selecting the optimum reference element without increasing computational complexity, especially for small GNSS arrays.

High-precision global navigation satellite system (GNSS) antennas employed on the fixed ground station are usually equipped with radomes, which are potential in yielding degradation of key parameters of antenna such as axial ratio and gain. This paper presents a study on the deterioration of high-precision GNSS antenna caused by the radome using electrically EM simulations including comparison of different geometries, materials, and heights of radome. Based on the study, an optimized radome model is proposed to minimize the axial ratio and gain degradation of antenna. Finally, a prototype of proposed radome is fabricated and measured. A good agreement between simulated and measured results evidently illustrates that the geometry, material, and height of radome are set appropriately.

Zero bias is the main source of error in high‐precision applications based on pseudo‐noise (PN) ranging. This study proposes a selective non‐commensurate sampling frequency design method applied to the digital code‐tracking loop which can effectively suppress the code‐phase zero bias caused by incomplete sampling of the spread spectrum signal. The maximum (MAX) and standard deviation (STD) of the zero bias independent of code and the initial phase are used to design the sampling frequency. The code correlation reference waveform is utilised to establish a statistical analysis model of the digital discriminator zero bias. Analytical expressions of the zero‐bias MAX and STD are derived. The performance of the proposed method is assessed as per code Doppler, binary offset modulation, and thermal noise. Fibre optic time synchronisation equipment is used to determine the feasibility of eliminating PN code‐tracking zero bias based on selective non‐commensurate sampling.

Carrier phase measurement is one of the most important measurements of GNSS receiver, which can be used for precise positioning. In order to achieve a reliable and high precise position, a high quality carrier-phase measurement is needed. Although carrier phase is very precise, there are also many factors in the receiver that will influence the carrier phase measurement performance. The relationship between the manufacturing costs and the high performance is a significant challenge. In order to make low costs, crystal oscillator is used in most GNSS receivers, which can introduce clock biases. This paper discusses GNSS carrier phase measurement model and how it is generated firstly. After that, the influence of clock bias on the double difference carrier-phase measurement is analyzed particularly. A new method is also proposed to remove the influence of the clock biases using instantaneous Doppler frequency and clock biases. Experimental results of zero-baseline test show that the influence of clock biases can be reduced by correcting the error term using the proposed method.