Ranging Performance for Spoofer Localization using Receiver Clock Offset

Precise point positioning (PPP) technique is an effective tool for time and frequency applications. Using phase/code observations and precise products, the PPP time transfer allows an accuracy of sub-nanoseconds within a latency of several days. Although the PPP time transfer is usually implemented in the post-processing mode, using the real-time PPP (RT-PPP) technique for time transfer with the shorter latency remains attractive to time community. In 2012, the IGS (International GNSS Service) launched an open-access real-time service (RTS) project, broadcasting satellite orbit and clock corrections on the Internet, which enables PPP time transfer in the real-time mode. In this contribution, we apply the RT-PPP for high-precision time transfer and synchronization. The GNSS receiver is required to be equipped with an atomic clock as the external local clock. We use the RT-PPP technique to compute the receiver clock offset with respective to the GNSS time scale. On the basis of clock offsets, we steer the local clock by frequency adjustment method. In this way, all the local clocks are synchronized to the GNSS time scale, making local clocks synchronized with each other.The time scales of the RTS products are evaluated at first. Six kinds of the RTS products (IGS01, CLK10, CLK53, CLK80 and CLK93) on DOY220-247, 2019 are pre-saved to compute the receiver clock offsets. The clock offset with respect to the GPST (GPS Time) obtained from the IGS final product is applied as the reference. The standard deviations (STDs) of the clock offsets with respect to the reference are 0.63, 1.76, 0.28, 0.27 and 1.28 ns for IGS01, CLK10, CLK53, CLK80 and CLK93, respectively.Finally, we set up a hardware system to examine the validity of our time synchronization method. The baseline of the time synchronization experiment is about 5 m. The synchronization error of the 1 PPS outputs is precisely measured by the frequency counter. The STD of the 4-days results is about 0.48 ns. The peak-to-peak value of the synchronization error is about 2.5 ns.

Download Full-text

Spoofing GPS Receiver Clock Offset of Phasor Measurement Units

IEEE Transactions on Power Systems ◽

10.1109/tpwrs.2013.2240706 ◽

2013 ◽

Vol 28 (3) ◽

pp. 3253-3262 ◽

Cited By ~ 98

Author(s):

Xichen Jiang ◽

Jiangmeng Zhang ◽

Brian J. Harding ◽

Jonathan J. Makela ◽

Alejandro D. Dominguez-Garcia

Keyword(s):

Phasor Measurement Units ◽

Gps Receiver ◽

Phasor Measurement ◽

Receiver Clock ◽

Measurement Units ◽

Clock Offset

Download Full-text

Analysis and improvement of the Bancroft algorithm for GNSS satellite orbit determination

Measurement Science and Technology ◽

10.1088/1361-6501/ac4434 ◽

2021 ◽

Author(s):

Yongchang Chen ◽

Chuanzhen Sheng ◽

Qingwu Yi ◽

Ran Li ◽

Guangqing Ma ◽

...

Keyword(s):

Orbit Determination ◽

Satellite Orbit ◽

Three Dimensions ◽

Single Frequency ◽

Precise Ephemeris ◽

Accuracy Level ◽

Receiver Clock ◽

The Impact ◽

Clock Offset ◽

Initial Orbit

Abstract Satellite orbit information is crucial for ensuring that global navigation satellite systems (GNSSs) provide appropriate positioning, navigation and timing services. Typically, users can obtain access to orbit information of a specific accuracy level from navigation messages or precise ephemeris products. Without this information, a system will not be able to provide normal service. In response to this problem, initial orbit information of a certain level of precision must be obtained to support subsequent applications, such as broadcasting or precise ephemeris calculations, thereby ensuring the successful subsequent operation of the navigation system. One of two ways to calculate the initial orbit of a GNSS satellite is to utilize ground tracking stations to observe satellite vector information in the geocentric inertial system; the second way is to utilize GNSS range observations and known orbit information from other satellites. For the second approach, some researchers use the Bancroft algorithm combined with receiver clock offset to determine the initial orbit of GNSS satellites. Because this method requires an additional known receiver clock offset, we study the dependence of the Bancroft algorithm on clock offset in GNSS orbit determination. By assessing the impact of errors of different magnitude on the accuracy of the orbit results, we obtain experimental conclusions. After comprehensively analyzing various errors, we determine the accuracy level that the Bancroft algorithm can achieve for orbit determination without considering receiver clock correction. Dual-frequency and single-frequency pseudorange data from IGS stations are used in orbit determination experiments. When a small receiver clock offset is considered and no correction is made, the deviations in the calculated satellite positions in three dimensions are approximately 979.3 and 1118.1 meters (dual and single frequency); with a satellite clock offset, these values are approximately 928.8 and 1062.7 meters (dual and single frequency).

Download Full-text

Real-Time Orbit Determination of Korean Navigation Satellite System based on Multi-GNSS Precise Point Positioning

E3S Web of Conferences ◽

10.1051/e3sconf/20199403008 ◽

2019 ◽

Vol 94 ◽

pp. 03008 ◽

Cited By ~ 1

Author(s):

Gimin Kim ◽

Hyungjik Oh ◽

Chandeok Park ◽

Seungmo Seo

Keyword(s):

Real Time ◽

Orbit Determination ◽

Precise Point Positioning ◽

Satellite System ◽

Navigation Satellite ◽

Receiver Clock ◽

Point Positioning ◽

Clock Offset ◽

Monitoring Stations

This study proposes real-time orbit/clock determination of Korean Navigation Satellite System (KNSS), which employs the kinematic precise point positioning (PPP) solutions of multiple Global Navigation Satellite System (multi-GNSS) to compensate for receiver clock oﬀset. Global visibility of KNSS satellites in terms of geometric coverage is first analyzed for the purpose of selecting optimal locations of KNSS monitoring stations among International GNSS Service (IGS) and Multi-GNSS Experiment (MGEX) network. While the receiver clock oﬀset is obtained from multi-GNSS PPP clock solutions of real observation data, KNSS measurements are simulated from the dynamically propagated KNSS reference orbit and the receiver clock oﬀset. The oﬀset and drift of satellite clock are also generated based on two-state clock model considering atomic clock noise. Real-time orbit determination results are compared with an artificially generated true or bit, wihch show 0.4m and 0.5m of 3-dimensional root-mean-square (RMS) position errors for geostationary (GEO) and ellitically-inclined-geosynchronous-orbit (EIGSO) satellites, respectively. The overall results show that the real-time precise orbit determination of KNSS should be achievable in meter level by installing KNSS-compatible multi-GNSS receivers on the IGS and/or MGEX network. The overall process can be also used to verify integrity of KNSS monitoring stations.

Download Full-text

COMPONENTS FOR TIME SERIE RECEIVER CLOCK OFFSET IN GPS SOLUTIONS

Computational Methods in Sciences and Engineering 2003 ◽

10.1142/9789812704658_0001 ◽

2003 ◽

Author(s):

P. ABAD

Keyword(s):

Receiver Clock ◽

Time Serie ◽

Clock Offset

Download Full-text

GNSS positioning algorithms using methods of reference point indicators

Artificial Satellites ◽

10.2478/arsa-2014-0002 ◽

2014 ◽

Vol 49 (1) ◽

pp. 21-32 ◽

Cited By ~ 1

Author(s):

Bartlomiej Oszczak

Keyword(s):

Least Squares ◽

Reference Point ◽

Least Squares Method ◽

Direct Solution ◽

Basic Principles ◽

Numerical Examples ◽

Gnss Receiver ◽

Gnss Positioning ◽

Receiver Clock ◽

Clock Offset

ABSTRACT The GNSS standard positioning solution determines the coordinates of the GNSS receiver and the receiver clock offset from measurements of at least four pseudoranges. For GNSS positioning, a direct solution was derived for five and ten observed satellites without linearisation of the observation equations and application of the least squares method. The article presents the basic principles of methods for solving the positioning problem, the formulas and their derivation. The numerical examples with simulated pseudorange data confirm the correct performance of the proposed algorithm. The presented algorithms should be further tested with real measurements in other domains of positioning and navigation as well.

Download Full-text

The Benefits of Receiver Clock Modelling in Satellite Timing

Sensors ◽

10.3390/s21020466 ◽

2021 ◽

Vol 21 (2) ◽

pp. 466

Author(s):

Weijin Qin ◽

Xiao Wang ◽

Hang Su ◽

Zhe Zhang ◽

Xiao Li ◽

...

Keyword(s):

White Noise ◽

Noise Model ◽

Kinematic Scheme ◽

Clock Model ◽

Average Improvement ◽

Receiver Clock ◽

Averaging Time ◽

Stochastic Clock ◽

Clock Offset ◽

Sampling Times

Satellite timing is an effective and convenient method that has been widely accepted in the time community. The key to satellite timing is obtaining a clean receiver clock offset. In this paper, instead of regarding the receiver clock offset as white noise, a two-state stochastic clock model involving three kinds of noise was conceived and used in PPP filter estimation. The influence of clock type and sampling time on satellite timing performance was first analysed. In addition, the kinematic scheme and static scheme were both investigated for meeting the demands of multi-occasional users. The values show that the model works well for both the kinematic scheme and static scheme; in contrast to that of the white noise model, the timing stability is enhanced at all the sampling times. For the six stations, especially when the averaging time is less than 1000 s, the average stability improvement values of the kinematic scheme are 75.53, 43.24, 75.00, 69.05, 40.57, and 25.45%, and the average improvement values of the static scheme are 65.49, 77.94, 56.71, 60.78, 64.41, and 39.41%. Furthermore, the enhancement magnitude is related to clock type. For a high-stability clock, the improvement of the kinematic scheme is greater than that of the static scheme, whereas for a low-stability clock, the improvement of the kinematic scheme is less than that of the static scheme.

Download Full-text