Abstract
This article proposes an indoor combined positioning terminal based on Beidou pseudofiles and micro-inertial navigation sensors. Through the built-in Beidou pseudo lite positioning IP soft ...core, it can receive and analyse Beidou satellite signals. The article creates BDS ground inertial positioning data receiving hardware; performs inertial positioning data primary information identification authentication on the inertial data received by the hardware; performs multi-inertial data fusion estimation calculation on inertial positioning data after authentication, reduces the dimensional error value, and completes the proposed system Design. The program makes full use of the data resources of the existing airborne equipment, does not need to transmit radio signals, and the user capacity is not limited, which is suitable for highly dynamic users. Through simulation and sports car test, it is proved that the scheme is feasible.
The total electron content (TEC) derived from ground‐based BeiDou geostationary orbit (GEO) satellite receivers lying on both sides of the eclipse path is used to study the ionospheric variations in ...southern China, particularly targeting eclipse‐induced gravity waves in the ionosphere during the annular solar eclipse on 21 June 2020. Eclipse‐induced gravity waves (GWs) signatures with periods of about 70 min, from wavelet analysis, were identified on both sides of TEC observations, which are most likely to be induced in the thermosphere. However, there were significant differences in the intensity of the gravity waves on both sides of the eclipse path, gravity waves are stronger on the northern side of the eclipse path than on the southern side. Moreover, a postponement of TEC depletion shows on the northern side of the eclipse path which is caused by the convergence effect of the wind field. And at the same obstruction rate, GWs possibly can slightly adjust the postponement of TEC depletion on a small scale.
Key Points
The eclipse‐induced thermospheric gravity waves are observed by BeiDou‐geostationary orbit total electron content (TEC) on both sides of the solar eclipse path
Gravity waves are stronger on the northern side of the eclipse path than that on the southern side due to convergence effects
The gravity waves on the northern side may slightly contribute to the postponement of the TEC depletion on a small scale
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This study proposes two models for precise time transfer using the BeiDou Navigation Satellite System triple-frequency signals: ionosphere-free (IF) combined precise point positioning (PPP) model ...with two dual-frequency combinations (IF-PPP1) and ionosphere-free combined PPP model with a single triple-frequency combination (IF-PPP2). A dataset with a short baseline (with a common external time frequency) and a long baseline are used for performance assessments. The results show that IF-PPP1 and IF-PPP2 models can both be used for precise time transfer using BeiDou Navigation Satellite System (BDS) triple-frequency signals, and the accuracy and stability of time transfer is the same in both cases, except for a constant system bias caused by the hardware delay of different frequencies, which can be removed by the parameter estimation and prediction with long time datasets or by a priori calibration.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This research is focused on searching for frequency and noise characteristics for available GNSS (Global Navigation Satellite Systems). The authors illustrated frequency stability and noise ...characteristics for a selected set of data from four different GNSS systems. For this purpose, 30-s-interval clock corrections were used for the GPS weeks 1982-2034 (the entirety of 2018). Firstly, phase data (raw clock corrections) were preprocessed for shifts and removal of outliers; GLONASS and GPS satellites characterize a smaller number of outliers than BeiDou and Galileo clock products. Secondly, frequency and Hadamard deviation were calculated. This study concludes that the stability of GPS and Galileo is better than that of BDS (BeiDou Navigation Satellite System) and GLONASS. Regarding noise, the GPS, Galileo, and BDS clocks are affected by the random walk modulation noise (RWFM), flashing frequency modulation noise (FFM), and white frequency modulation noise (WFM), whereas the GLONASS clocks are mainly affected only by WFM.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The need for high-precision and dependable navigation and positioning services is rising in the mass market as a result of the Beidou navigation satellite system (BDS-3)’s completion and the ...performance development of smartphone chips. However, compared with the geodesic receiver, the positioning accuracy of smartphones is severely degraded due to the low antenna gain and poor anti-interference ability. In March 2022, Redmi released K50 smartphones that support BDS trifrequency, providing conditions for further improvement of smartphone positioning. First, we collected the multiconstellation and multifrequency data of the K50 to evaluate the availability of trifrequency observations. Then, we compared the observations between different frequencies and found that the pseudorange data quality of the L5/E5a is better than that of L1/E1. For the BDS, the pseudorange data quality of the B2a is obviously better than that of the other two frequencies. For carrier observations, expect for the initial phase biases (IPB) of B1C, there is no significant difference in data quality between different frequencies. It means that the traditional random model cannot accurately reflect the pseudorange quality of smartphone observation. We used the zero-baseline double difference residual method to calculate the smartphone observation accuracy and refined the random model. Finally, we verified the performance of the refined model through location tests. The results show that the model refinement can significantly improve positioning accuracy and reliability in the single point positioning test and shorten the convergence time in relative positioning. In kinematic positioning, the improved model can obtain the positioning accuracy of a single epoch centimeter level even when the signal is slightly blocked, which is of great significance for high-precision navigation of smartphones in urban environments.
BeiDou Global Navigation Satellite System (BDS-3) not only performs the normal positioning, navigation and timing (PNT) functions, but also provides featured services, which are divided into ...geostationary orbit (GEO) and medium earth orbit (MEO) satellite-based featured services in this paper. The former refers to regional services consisting of the regional short message communication service (RSMCS), the radio determination satellite service (RDSS), the BDS satellite-based augmented service (BDSBAS) and the satellite-based precise point positioning service via B2b signal (B2b-PPP). The latter refers to global services consisting of the global short message communication service (GSMCS) and the MEO satellite-based search and rescue (MEOSAR) service. The focus of this paper is to describe these featured services and evaluate their performances. The results show that the inter-satellite link (ISL) contributes a lot to the accuracy improvement of orbit determination and time synchronization for the whole constellation. Compared with some other final products, the root mean squares (RMS) of the BDS-3 precise orbits and broadcast clock are 25.1 cm and 2.01 ns, respectively. The positioning accuracy of single frequency is better than 6 m, and that of the generalized RDSS is usually better than 12 m. For featured services, the success rates of RSMCS and GSMCS are better than 99.9% and 95.6%, respectively; the positioning accuracies of single and dual frequency BDSBAS are better than 3 and 2 m, respectively; the positioning accuracy of B2b-PPP is better than 0.6 m, and the convergence time is usually smaller than 30 min; the single station test shows that the success rate of MEOSAR is better than 99%. Due to the ISL realization in the BDS-3 constellation, the performance and capacities of the global featured services are improved significantly.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The BeiDou Navigation Satellite System is expected to provide a global positioning and navigation service by 2020. To achieve this goal, the new-generation navigation satellites that have been ...launched since March 2015 are equipped with inter-satellite links (ISLs), with the objective of testing new navigation signals and the ISLs themselves. Using these new-generation navigation satellites and several ground facilities in China, a combined orbit determination experiment was carried out during August 2016. The orbit mechanical model, orbit determination method, and accuracy evaluation method used in this experiment are presented here. The accuracy of the combined orbit determination method is evaluated, and the performance-related improvements resulting from the ISLs are analyzed. The performance of orbit determination has been increased about 37–76% for different satellites in orbit-only signal-in-space range error (orbit-only SISRE).
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
This paper analyzes the inter-system deviation between B1I/B3I semaphores and B1I/B3I and B1C/B2a semaphores of Beidou-2 and Beidou-3 semaphores, and analyzes the precision single ...independent point locationperformance of Beidou-2 / Beidou-3 semaphores under the condition of B1I/B3I and B1C/B2a semaphores. Through the experiment, the system deviation parameters between B1C/B2a semaphores of the two satellite systems are greater than that of B1I/B3I semaphores, and both have good intra-day and inter-day stability. The participation of Beidou-3 satellite system can significantly improve the positioning function precision one point positioning of Beidou-2. The location astringent time is reduced by about 51.9%, and the positioning accuracy is increased by about 46.1%. Compared with B1I/B3I semaphores, after B1C/B2a semaphores of Beidou-3 participate in precision single independent point locationcalculation, the astringent time of precision single point location is greatly shortened. After estimating and correcting the system deviation parameters, the astringent time of static and dynami PPP of the two satellite systems is shortened by 8.8% and 12.6% respectively, and the positioning precision is promoted by 7.1%.
To provide high-precision timing services of the BeiDou Navigation Satellite System (BDS), this work performs a detailed investigation of integrated BDS-3 and BDS-2 real-time precise point ...positioning (PPP) time transfer with the ultrarapid products. Compared with the final precise clock products, the average standard deviation (STD) of estimated BDS-3 MEO/IGSO satellites is 0.1 ns, while the corresponding value of BDS-2 is 0.2 ns. The precision of real-time BDS-3/2 PPP time transfer can achieve better than 0.5 ns. The phenomenon of reconvergence and abnormal jumps in receiver clock series can be effectively reduced because of the evenly distributed MEO satellites.
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