TITLE:
Improved Between-Satellite Single-Difference Precise Point Positioning Model Using Triple GNSS Constellations: GPS, Galileo, and BeiDou
AUTHORS:
Akram Afifi, Ahmed El-Rabbany
KEYWORDS:
PPP, BSSD, GPS, Galileo, BeiDou
JOURNAL NAME:
Positioning,
Vol.7 No.2,
May
12,
2016
ABSTRACT: This paper introduces a new dual-frequency precise
point positioning (PPP) model, which combines the observations of three different
GNSS constellations, namely GPS, Galileo, and BeiDou. Our model is based on between-satellite
single-difference (BSSD) linear combination, which cancels out some receiver-related
biases, including receiver clock error and non-zero initial phase bias of the receiver
oscillator. The reference satellite can be selected from any satellite system GPS,
Galileo, and BeiDou when forming BSSD linear combinations. Natural Resources Canada’s
GPS Pace PPP software is modified to enable a combined GPS, Galileo, and
BeiDou PPP solution and to handle the newly introduced biases. A total of four data
sets at four IGS stations are processed to verify the developed PPP model. Precise
satellite orbit and clock products from the IGS-MGEX network are used to correct
both of the GPS and Galileo measurements. It is shown that using the BSSD linear
combinations improves the precision of the estimated parameters by about 25% compared
with the GPS-only PPP solution. Additionally, the solution convergence time is reduced
to 10 minutes for both BSSD scenarios, which represent about 50% improvement in
comparison with the GPS-only PPP solution.