相位锁定指示值与GNSS观测值质量分析

Quality analysis of GNSS observations and phase lock detector

全球卫星导航系统(GNSS)信号易受外界环境干扰,出现衰弱或短暂丢失现象,影响载波相位观测值的质量。相位锁定指示(PLD)值P_(LDR)是一种载波相位跟踪性能的度量,用于指示信号跟踪状态和评估载波相位的跟踪能力。为深入研究P_(LDR)与GNSS观测值质量的关系,对空旷、树荫、墙角和玻璃幕墙环境中P_(LDR)、载噪比、高度角、周跳和载波相位残差间的关系进行分析,结果表明:在空旷环境中,P_(LDR)与载噪比、高度角强相关;在树荫等复杂环境中,P_(LDR)与载噪比强相关,但与高度角无明显相关性;在所有环境中,P_(LDR)与周跳发生概率的相关性强,与载波相位残差的周期性变化部分相关性强且没有时延现象,但P_(LDR)不能反映载波相位双差残差的总体变化趋势。为验证P_(LDR)作为观测值质量指标的有效性,建立了一种顾及P_(LDR)的高度角随机模型,实验结果表明,新模型可有效提升定位精度与可靠性。

The Global Navigation Satellite System(GNSS)signal is easy to be jammed,sometimes weakens or even losses and these phenomena will affect the quality of carrier phase observations seriously.Phase Lock Detector(PLD)P_(LDR)is a measurement of the tracking performance of carrier phase used to show signal tracking status and evaluate the tracking ability.The relationship between the P_(LDR),satellite elevation,cycle slips and the carrier phase observation residual is analyzed in the open,shades,corner and the glass curtain wall environment in order to further study the relationship between P_(LDR)and GNSS observations.The results indicate that the P_(LDR)has a high correlation with the elevation and Signal-to-Noise Ratio(SNR)in the open environment.The P_(LDR)is strongly correlated with the SNR but not with the elevation in a complex environment such as tree shade.P_(LDR)has a strong correlation with cycle skip occurrence probability in all kinds of environments,and has a strong partial correlation with the periodic change of carrier phase residuals and without delay phenomenon.However,P_(LDR)cannot reflect the general trend of carrier phase residuals.In order to verify the effectiveness ofP_(LDR)as the quality index of the observations,the stochastic model with combined P_(LDR)and satellite elevation was established.The experimental results show that the model can effectively improve the positioning accuracy and reliability.