Analysis And Estimation Of GNSS Biases Based On A Single Receiver

Global Navigation Satellite System biases significantly degrade the performance using GNSS for precise positioning,ionospheric remote sensing,and time transfer.GNSS biases occur because of imperfections and physics limitations in satellite and receiver hardware.To date,the researches of GNSS biases are mainly based on the receiver outputs.Analysis and estimate GNSS satellite and receiver biases together and then separate them outside receivers.However,the causes and characteristics of GNSS receiver biases have not been well studied.Order to clarify the causes of GNSS biases due to the signal processing process in-receiver.The classification of GNSS receiver induced biases has first been investigated to analyze the in-receiver bias sources.The existing biases are classified from the perspective of equipment,data,and system,and the shortage of existing biases estimation methods are extracted.This thesis analysis and estimate the receiver induced pseudorange and carrier phase biases.The analysis of correlator spacing influences on the single-frequency positioning,the fractional cycle biases estimation,and the differential code bias estimation based on a correlator spacing flexible software receiver.(1)Analysis of GNSS receiver bias sourcesAiming at the problem of insufficient quantitative analysis of bias sources in a receiver,the analysis of in-receiver bias sources is conducted based on in-receiver analog signal processing and digital signal processing process.The calibration of GNSS in-receiver signal processing process induced biases has been investigated based on a software receiver from the data collected by two dual-channel radio-frequency(RF)front-ends and a coordinate correct antenna.The front-end local oscillator,chip,ADC,and the baseband correlator spacing induced biases have been estimated and analyzed for the same frequency.The results show that the front-end induced biases cannot be ignored and cannot be simply included in a certain error when using multi-receiver observations.The correlator spacing induced biases have significant satellite differences based on the analysis of simulated signal and living antenna signal.(2)Analysis of inter-spacing biases influence on single-frequency positioningAiming at the problem that the receiver's inter-spacing biases are not effectively used,the influence of the satellite-dependent inter-spacing biases on the single-frequency positioning is firstly analyzed.The single-receiver single-frequency pseudorange based between spacing realtime difference(BSRTD)algorithm and the carrier phase based between spacing real-time kinematic(BSRTK)algorithm are proposed.The between spacing difference algorithms can reduce the number of receivers required by the single-frequency differential positioning algorithm.They do not require additional data transmission equipment,which can effectively reduce the cost of differential positioning and improve the efficiency of single-frequency signal utilization.The experimental results show that the BSRTD and the BSRTK algorithms can effectively improve the single-receiver single-frequency relative positioning accuracy.(3)Single-receiver GNSS fractional cycle bias estimation methodAiming at the poor real-time performance of the receiver network-based phase fractional cycle bias(FCB)estimation method,a single receiver multi-spacing FCB(MSFCB)estimation method is proposed.This method is based on the independent pseudorange and carrier phase observations tracked by different correlator spacings.The MSFCB method uses a correlator spacings flexible software receiver to increase the number of observations of a single satellite on a single receiver and realize a single receiver to simulate the distribution of multiple reference stations.And then estimate the satellite FCB,improving the real-time performance of the FCB estimation.The experimental results show that the MSFCB estimation algorithm can estimate satellite wide-lane and narrow-lane FCBs,which can be used to fix the integer ambiguity.(4)Multi-spacing GNSS differential code bias estimation methodAiming at the problem that differential code bias(DCB)estimation requires mount of observations and poor real-time performance.A single-receiver multi-spacing DCB(MSDCB)estimation method is proposed based on the observations of pseudoranges and carrier phases of different correlator spacings independent of each other.The influence of the variation of a single receiver spacing on the multi-station DCB estimation method is first analyzed.The multispacing observations used in the MSDCB method can improve the calculation accuracy of the ionospheric puncture point distribution of the single receiver.The experimental results show that the satellite DCB obtained by the MSDCB method can achieve accuracy similar to that of the multi-receiver DCB estimation algorithm.