Article
Study on Multi-GNSS Precise Point Positioning
Performance with Adverse Effects of Satellite Signals
on Android Smartphone
Hongyu Zhu
1
, Linyuan Xia
1,
*, Dongjin Wu
1
, Jingchao Xia
2
and Qianxia Li
1
1
School of Geography and Planning, Sun Yat-Sen University, Guangzhou 510000, China;
zhuhy35@mail2.sysu.edu.cn (H.Z.); wudj3@mail.sysu.edu.cn (D.W.); liqianx2@mail2.sysu.edu.cn (Q.L.)
2
School of Civil Engineering, Guangzhou University, Guangzhou 510000, China; jcxia@gzhu.edu.cn
* Correspondence: xialiny@mail.sysu.edu.cn; Tel.: +86-20-8411-5833
Received: 26 September 2020; Accepted: 9 November 2020; Published: 11 November 2020
Abstract:
The emergence of dual frequency global navigation satellite system (GNSS) chip actively
promotes the progress of precise point positioning (PPP) technology in Android smartphones.
However, some characteristics of GNSS signals on current smartphones still adversely affect the
positioning accuracy of multi-GNSS PPP. In order to reduce the adverse effects on positioning,
this paper takes Huawei Mate30 as the experimental object and presents the analysis of multi-GNSS
observations from the aspects of carrier-to-noise ratio, cycle slip, gradual accumulation of phase error,
and pseudorange residual. Accordingly, we establish a multi-GNSS PPP mathematical model that is
more suitable for GNSS observations from a smartphone. The stochastic model is composed of GNSS
step function variances depending on carrier-to-noise ratio, and the robust Kalman filter is applied to
parameter estimation. The multi-GNSS experimental results show that the proposed PPP method can
significantly reduce the effect of poor satellite signal quality on positioning accuracy. Compared with
the conventional PPP model, the root mean square (RMS) of GPS/BeiDou (BDS)/GLONASS static
PPP horizontal and vertical errors in the initial 10 min decreased by 23.71% and 62.06%, respectively,
and the horizontal positioning accuracy reached 10 cm within 100 min. Meanwhile, the kinematic
PPP maximum three-dimensional positioning error of GPS/BDS/GLONASS decreased from 16.543 to
10.317 m.
Keywords:
Android smartphone; precise point positioning; multi-GNSS; stochastic model;
robust Kalman filter; gradual accumulation of phase error
1. Introduction
At the May 2016 Google I/O developer conference, it was announced that general developers
would be provided with the raw global navigation satellite system (GNSS) measurements of
smartphones and tablets with Android N (“Nougat” = version 7) version operating system [
1
],
which enables the raw GNSS observations of smartphone to output directly in RENIX format with
application (APP). This makes it extremely convenient to obtain the GNSS pseudorange, doppler,
signal strength, and carrier phase measurements from an Android smartphone for postprocessing [
2
].
Moreover, in September 2017, Broadcom announced the world’s first dual frequency GNSS chip
GCM47755 [
3
], and other producers quickly followed suit with new dual frequency chips. Since then,
the GNSS positioning method of smartphones has evolved from single frequency to dual frequency,
which provides more ideas for smartphones to achieve high-precision positioning.
In fact, prior to the Google I/O developer conference, Humphreys et al. [
4
] had discussed the
feasibility of centimeter-level positioning via the smartphone’s antenna and GNSS chip. The feasibility
Sensors 2020, 20, 6447; doi:10.3390/s20226447 www.mdpi.com/journal/sensors
