Jing Peng

Bio: Jing Peng is an academic researcher from National University of Defense Technology. The author has contributed to research in topics: GNSS applications & Global Positioning System. The author has an hindex of 2, co-authored 4 publications receiving 17 citations.

GNSS Performance Research for MEO, GEO, and HEO

Abstract: GNSSs such as GPS, GLONASS, Galileo, and Beidou have demonstrated to be a valid and efficient system for various space applications in LEO. Since the 1990s precise GNSS-based positioning of GEO, MEO, HEO, and even deep space exploration satellites has also been considered feasible. This paper analyzes the GNSS satellite visibility and PDOP performances for 6 space users, including two GEO, one MEO, and three HEO satellites. The simulation results show that a single GNSS receiver with the sensitivity of about −180 to −188 dBW is enough for space user below 50,000 km while the receiver of a Lunar explorer must be able to process the received signal low to −202 ~ −208 dBW. As for a multi-GNSS receiver, the sensitivity requirements decrease about 2–4 dBW compared with the single GNSS one. Viewed from the sensitivity standpoint, a GPS-only receiver and a BDS+GPS receiver are the best single GNSS and multi-GNSS choice for most of the six space users while a Beidou-only receiver performs the best for GEO1 satellite which is fixed above the Asia-Pacific area. It can be concluded that for the space users below 50,000 km, it is possible to attain an average PDOP of below 20 with a receiver sensitivity no higher than −184 dBW. An important conclusion drawn from the analysis is that the higher the space user flies, the more important role multi-GNSS application plays.

Research on Integrity Monitoring Techniques for Atomic Clocks Based on DualKalman Filter

Abstract: As the core component of time-frequency reference generation of satellite navigation system, atomic clock is the guarantee for high-precision navigation signal generation and reception. The integrity monitoring of atomic clocks is the basis for time reference generation and spatial high-precision measurement. This paper adopts the idea of Kalman filter prediction residuals for integrity monitoring, establishes an accurate Kalman filter model of the atomic clock, constructs the Kalman prediction residual vector, and performs two-level Kalman filtering to form a DualKalman filter to improve detection sensitivity. Using IGS data to analyze the calculation examples, the results show that the DualKalman filter integrity detection technology proposed in this paper has the characteristics of high-sensitivity detection and can be used as a GNSS ground/satellite clock integrity monitoring method.

A Kalman Filter Clock Algorithm for Use in the Presence of Flicker Frequency Modulation Noise

Abstract: The National Physical Laboratory (NPL) has developed a Kalman filter based algorithm for combining measurements from its three active hydrogen masers. The algorithm is designed to produce a near optimal composite clock when the dominant noise process of at least one of the masers is flicker frequency modulation (FFM), and significant linear frequency drift is exhibited. The FFM is modelled approximately by a linear combination of Markov noise processes. Each Markov process is included in the Kalman filter and contributes an additional component to the state vector. Both the validity of the model and the effectiveness of adding these additional components are examined. The performance of the new algorithm is investigated when applied to simulated measurements and also to measurements obtained from NPL's hydrogen masers.

An Improved Predicted Model for BDS Ultra-Rapid Satellite Clock Offsets

Abstract: The satellite clocks used in the BeiDou-2 satellite navigation System (BDS) are Chinese self-developed Rb atomic clocks, and their performances and stabilities are worse than GPS and Galileo satellite clocks. Due to special periodic noises and nonlinear system errors existing in the BDS clock offset series, the GPS ultra-rapid clock model, which uses a simple quadratic polynomial plus one periodic is not suitable for BDS. Therefore, an improved prediction model for BDS satellite clocks is proposed in order to enhance the precision of ultra-rapid predicted clock offsets. First, a basic quadratic polynomial model which is fit for the rubidium (Rb) clock is constructed for BDS. Second, the main cyclic terms are detected and identified by the Fast Fourier Transform (FFT) method according to every satellite clock offset series. The detected results show that most BDS clocks have special cyclic terms which are different from the orbit periods. Therefore, two main cyclic terms are added to absorb the periodic effects. Third, after the quadratic polynomial plus two periodic fitting, some evident nonlinear system errors also exist in the model residual, and the Back Propagation (BP) neural network model is chosen to compensate for these nonlinear system errors. The simulation results show that the performance and precision using the improved model are better than that of China iGMAS ultra-rapid prediction (ISU-P) products and the Deutsches GeoForschungsZentrum GFZ BDS ultra-rapid prediction (GBU-P) products. Comparing to ISU-P products, the average improvements using the proposed model in 3 h, 6 h, 12 h and 24 h are 23.1%, 21.3%, 20.2%, and 19.8%, respectively. Meanwhile the accuracy improvements of the proposed model are 9.9%, 13.9%, 17.3%, and 21.2% compared to GBU-P products. In addition, the kinematic Precise Point Positioning (PPP) example using 8 Multi-GNSS Experiment MGEX stations shows that the precision based on the proposed clock model has improved about 16%, 14%, and 38% in the North (N), East (E) and Height (H) components.

Comprehensive Analyses of PPP-B2b Performance in China and Surrounding Areas

Abstract: BeiDou Global Navigation Satellite System (BDS-3) provides a regional Precise Point Positioning (PPP) service, called PPP-B2b, for users in China and surrounding areas through B2b signal transmitted from its three geostationary earth orbit (GEO) satellites. The information broadcasted by the B2b signal include satellite orbit corrections, satellite clock offset corrections, and differential code bias (DCB) corrections of BDS-3 satellites. In this study, the accuracies of PPP-B2b corrections along with real-time PPP performance are comprehensively evaluated referenced to precise orbit and clock products from GFZ and the precise DCB products from CAS. The result indicates that the accuracy of the BDS-3 broadcast orbit is similar to that of the PPP-B2b real-time orbit. The PPP-B2b clock offset correction improved the satellite clock offset precision of the BDS-3 broadcast ephemeris. The Signal-in-Space Range Error (SISRE) of broadcast ephemeris and PPP-B2b are calculated, which are 0.536 and 1.24 m, respectively. The large SISRE value of PPP-B2b is caused by the satellite-specified systematic bias to IGS final products. The positioning performance evaluation of real-time PPP with B2b service is carried out and compared with the real-time product provided by Wuhan University (WHU) based on the eight IGS MGEX stations in China and surrounding countries. The positioning accuracy of static positioning mode with PPP-B2b service achieved centimeter-level accuracy in the selected station, and that of kinematic positioning mode achieved decimeter-level accuracy. The availability rate of PPP-B2b corrections in the surrounding area of China, however, degrades from 88.76% to 60.91% in the selected stations. The accuracy of the PPP solution using PPP-B2b correction is better than that of using WHU real-time product within China. The positioning performance of stations located at the boundary of the PPP-B2b service area, however, is affected by the number of PPP-B2b available satellites. The positioning accuracy in kinematic positioning mode is worse than that of using WHU real-time precise product.

TJS-2 geostationary satellite orbit determination using onboard GPS measurements

Abstract: This study analyzes the quality of onboard data of tracking signals from GPS satellites on the far side of the earth and determines the orbit of the geostationary satellite using code and carrier phase observations with 30-h and 3-day orbit arc length. According to the analysis results, the onboard receiver can track 6–8 GPS satellites, and the minimum and maximum carrier to noise spectral densities were 24 and 45 dB-Hz, respectively. For a GPS receiver on a high-altitude platform above the navigation constellations, the blocking of the earth and a weak signal strength usually cause a piece-wise GPS signal tracking and an increase in the number of ambiguity parameters. Individual GPS satellites may be continuously tracked for as little as several minutes and as long as 3 h. Moreover, considering the negative sign of elevation angles reflects the fact that GPS satellites are tracked below the receiver in the study. GPS satellites appear mainly in the elevation angle range of − 53° to − 83°, and dilution of precision values could reach ten or one hundred and more. Also, it is observed that when a signal suffers from atmospheric refraction, other GPS signals tracked simultaneously by the receiver experience strong systematic errors in the code observations. Based on single-frequency code and carrier phase measurements, the mean 3D root mean square (RMS) value of the overlap comparisons between 30-h orbit determination arcs is 2.14 m. However, we found that there were also some biases in the carrier phase residuals, which contributed to poor orbit accuracy. To eliminate the effects of the biases, we established a correction sequence for each GPS satellite. After corrections, the mean 3D RMS was reduced to 0.99 m, representing a 53% improvement.

GNSS Performance Research for MEO, GEO, and HEO

Abstract: GNSSs such as GPS, GLONASS, Galileo, and Beidou have demonstrated to be a valid and efficient system for various space applications in LEO. Since the 1990s precise GNSS-based positioning of GEO, MEO, HEO, and even deep space exploration satellites has also been considered feasible. This paper analyzes the GNSS satellite visibility and PDOP performances for 6 space users, including two GEO, one MEO, and three HEO satellites. The simulation results show that a single GNSS receiver with the sensitivity of about −180 to −188 dBW is enough for space user below 50,000 km while the receiver of a Lunar explorer must be able to process the received signal low to −202 ~ −208 dBW. As for a multi-GNSS receiver, the sensitivity requirements decrease about 2–4 dBW compared with the single GNSS one. Viewed from the sensitivity standpoint, a GPS-only receiver and a BDS+GPS receiver are the best single GNSS and multi-GNSS choice for most of the six space users while a Beidou-only receiver performs the best for GEO1 satellite which is fixed above the Asia-Pacific area. It can be concluded that for the space users below 50,000 km, it is possible to attain an average PDOP of below 20 with a receiver sensitivity no higher than −184 dBW. An important conclusion drawn from the analysis is that the higher the space user flies, the more important role multi-GNSS application plays.