Instrumentation & Measurement Magazine 25-5 - 30

Study on PPP Time Comparison
Based on BeiDou-3 New Signal
Jihai Zhang, Shaowu Dong, Haibo Yuan, Wei Guang, Yu Zhang,
Jian Zhang, Meng Jiang, and Huijie Song
T
he Chinese BeiDou Navigation Satellite System
(BDS-3) has completed the network construction
and begun to provide high-precision Positioning,
Navigation, and Timing (PNT) services for users all over
the world. In this paper, we study the Precision Point Positioning
(PPP) time comparison based on the BDS-3 new
signal. The data presented in this paper includes the observation
data from the National Time Service Center of
Chinese Academy of the Sciences (NTSC) and the Electronics
Academy of Sciences in Czech Republic (TP), and the
precise product data released by the International GNSS
Service (IGS), which includes the high-precision clock and
orbit products. The results show that the multipath noise
of the BDS-3 new signal (B1C and B2a) is less than that of
the Asia-Pacific region BDS-2 (B1I and B2I), and the standard
deviation (STD) of the multipath noise of B2a is the
least. When the BDS-3 PPP is applied to the common clock
short-baseline time comparison, the standard deviations of
the BDS-3 and BDS-2 signals are 0.0296 ns and 0.0341 ns, respectively,
the standard deviation of BDS-3 is smaller than
that of BDS-2, and therefore the short-baseline time comparison
performance of BDS-3 PPP is better than that of
BDS-2, the standard deviation of BDS-3 PPP has increased
by 13.19% compared with BDS-2. For long-baseline time
comparisons between UTC (NTSC) and UTC (TP), the results
based on the BDS-3 single system, or BDS-3 with other
navigation system fusion PPP time comparison, follow
the same trend as the results released by the International
Bureau of Weights and Measures (BIPM). The residual
standard deviations relative to the BIPM are 0.7039 ns and
0.2994 ns respectively. The stability of the BDS-3 new signal
PPP and multi-GNSS fusion PPP time comparison has
the same magnitude as the BIPM. As a result, with the completion
of BDS-3, the high-precision time comparison based
on BDS-3 expected to offer better services for users. The experimental
results demonstrate that BDS-3 could be used
to calculate the Coordinated Universal Time (UTC) in the
future.
30
Research Background and Significance
The high-precision time comparison method based on the
Global Navigation Satellite System (GNSS) is widely used
by different time keeping laboratories and BIPM for UTC calculation
[1], [2]. At present, among the four major satellite
navigation systems in the world, the Global Position System
(GPS), which is owned by the United States government, is the
first out of four GNSS that was built. It features stability, reliability,
and high precision. With hundreds of tracking stations
around the globe providing satellite monitoring data, the GPS
has become the choice for the majority of users. Currently, more
than 80 time keeping laboratories have registered in the BIPM.
All time keeping laboratories realize and maintain the UTC
(k), in which k represents the different time keeping laboratory,
that is the physical signal of UTC. More than 50 laboratories
steered their UTC (k) to UTC by GPS PPP [3]. To improve UTC
accuracy, stability and reliability, the Consultative Committee
for Time and Frequency (CCTF) recommended that the multitechnology
time comparison methods be applied to UTC
calculation in 2009. In the same year, the time comparison date
provided by GLONASS was first adopted in UTC production,
and the data of the GLONASS time comparison link was released
in the No.263 of Circular*T.
At the 21st CCTF working group meeting in 2017, BIPM
experts recommended that the time comparison technology
based on BDS be used in UTC calculation as backup for other
navigation satellite systems. Lately, with the construction of
the BDS, it has gone through the China region service phase
(BDS-1), China and Asia-Pacific region service phase (BDS2),
global basic service phase (BDS-3 basic system), and global
complete system (BDS-3 global system). The last BDS-3 satellite
was successfully launched on May 23, 2020, marking the
completion of the BDS-3 system construction. The BDS-3 system
includes three geosynchronous orbit (GEO) satellites, 24
medium earth orbit (MEO) satellites and three inclined geosynchronous
orbit (IGSO) satellites [4], [5]. The high-quality
services of positioning, navigation and timing have benefited
users all over the world.
IEEE Instrumentation & Measurement Magazine
1094-6969/22/$25.00©2022IEEE
August 2022
Instrumentation & Measurement Magazine 25-5

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