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Conditioning and PPP processing of smartphone GNSS measurements in realistic environments

Satellite Navigation 2021年第1期2卷 141-157页

作者： Ganga Shinghal sunil bisnath Department of Earth and Space Science and Engineering Lassonde School of EngineeringYork UniversityTorontoCanada

Smartphones typically compute position using duty-cycled Global Navigation Satellite System (GNSS) L1 code measurements and Single Point Positioning (SPP) processing with the aid of cellular and other measurements. This internal positioning solution has an accuracy of several tens to hundreds of meters in realistic environments (hand-held, vehicle dashboard, suburban, urban forested, etc.). With the advent of multi-constellation, dual-frequency GNSS chips in smartphones, along with the ability to extract raw code and carrier-phase measurements, it is possible to use Precise Point Positioning (PPP) to improve positioning without any additional equipment. This research analyses GNSS measurement quality parameters from a Xiaomi MI 8 dual-frequency smartphone in varied, realistic environments. In such environments, the system suffers from frequent phase loss-of-lock leading to data gaps. The smartphone measurements have low and irregular carrier-to-noise (C/N0) density ratio and high multipath, which leads to poor or no positioning solution. These problems are addressed by implementing a prediction technique for data gaps and a C/N0-based stochastic model for assigning realistic a priori weights to the observables in the PPP processing engine. Using these conditioning techniques, there is a 64% decrease in the horizontal positioning Root Mean Square (RMS) error and 100% positioning solution availability in sub-urban environments tested. The horizontal and 3D RMS were 20 cm and 30 cm respectively in a static open-sky environment and the horizontal RMS for the realistic kinematic scenario was 7 m with the phone on the dashboard of the car, using the SwiftNav Piksi Real-Time Kinematic (RTK) solu-tion as reference. The PPP solution, computed using the YorkU PPP engine, also had a 5-10% percentage point more availability than the RTK solution, computed using RTKLIB software, since missing measurements in the logged file cause epoch rejection and a non-continuous solution, a

关键词： PPP Smartphone Realistic environment Prediction C/N0-based stochastic modeling Internal phone solution Positioning solution comparison

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On error analysis and station monitoring of GNSS RTK networks through baseline network adjustment

On error analysis and station monitoring of GNSS RTK network...

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第九届中国卫星导航学术年会

作者： Jianguo Wang Xieqiu Jia sunil bisnath Department of Earth and Space Science and Engineering Lassonde School of Engineering york University

Although the application of GNSS RTK networks becomes a standard technique in positioning practice, its error analysis is mostly conducted within the baseline processing, but not with an overdetermined baseline network. With the baselines derived from the simultaneously acquired measurements within a GNSS RTK network, the network shows a lack of redundant baseline measurements and does not allow a meaningful least-squares adjustment. Hence, it remains a challenge how to conduct an appropriate error analysis in a GNSS RTK network at network level. This research proposes a practically operational strategy to enable the least-squares adjustment of a GNSS RTK network by integrating two groups of the independent baselines after two different formations over two successive time slots so that the posteriori accuracy assessment, removal of outlying baselines, and then preliminary identification of network stations with significant position displacements can be performed at network level. The proposed strategy has been tested out through real GNSS RTK networks and has showed its feasibility and advantages.

关键词： RTK network baseline network adjustment error analysis at network level free network outlier detection station stability identification

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解决GPS载波相位跳周问题的新方法

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控制工程（北京） 2001年第4期 50-57页

作者： sunil B.bisnath Donghyun Kim Richard B.Langley 高益军

1 引言高精度的GPS定位和导航要求在数据预处理阶段正确修正载波相位观测量中所包含的跳周。仅一二个周期的跳变所引起的测量偏差就使厘米级的定位和导航难以实现。过去十几年内,研究人员已经开发了多种检测和修正跳周的方法。然而,常... 详细信息

1 引言高精度的GPS定位和导航要求在数据预处理阶段正确修正载波相位观测量中所包含的跳周。仅一二个周期的跳变所引起的测量偏差就使厘米级的定位和导航难以实现。过去十几年内,研究人员已经开发了多种检测和修正跳周的方法。然而,常常仍有一二个跳周不能检测和正确修正,需要分析人员参与,才能完成数据处理,因此,一个操作性能完善的自动化GPS数据预处理器仍是我们可望而不可及的目标。尽管这样。

关键词：跳周修正检测观测量全球卫星定位系统 GPS 载波相位数据处理

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