Diversity Systems Comparison of Satellite Visibility Improvement for Designing Mobile Broadcasting Satellite System

2006 ◽  
Vol 54 (8) ◽  
pp. 2365-2370 ◽  
Author(s):  
T. Hatsuda ◽  
K. Hashimoto ◽  
J. Masuda ◽  
J. Murakami
Keyword(s):  
Satellite System ◽  
Satellite Visibility ◽  
Diversity Systems ◽  
Mobile Broadcasting ◽  
Visibility Improvement

scholarly journals High-Accuracy Real-Time Kinematic Positioning with Multiple Rover Receivers Sharing Common Clock

2021 ◽  
Vol 13 (4) ◽  
pp. 823
Author(s):  
Lin Zhao ◽  
Jiachang Jiang ◽  
Liang Li ◽  
Chun Jia ◽  
Jianhua Cheng
Keyword(s):  
Real Time ◽  
Ambiguity Resolution ◽  
Temporal Stability ◽  
Estimation Method ◽  
Satellite System ◽  
Integer Ambiguity ◽  
Dual Frequency ◽  
Kinematic Positioning ◽  
Real Time Kinematic ◽  
Satellite Visibility

Since the traditional real-time kinematic positioning method is limited by the reduced satellite visibility from the deprived navigational environments, we, therefore, propose an improved RTK method with multiple rover receivers sharing a common clock. The proposed method can enhance observational redundancy by blending the observations from each rover receiver together so that the model strength will be improved. Integer ambiguity resolution of the proposed method is challenged in the presence of several inter-receiver biases (IRB). The IRB including inter-receiver code bias (IRCB) and inter-receiver phase bias (IRPB) is calibrated by the pre-estimation method because of their temporal stability. Multiple BeiDou Navigation Satellite System (BDS) dual-frequency datasets are collected to test the proposed method. The experimental results have shown that the IRCB and IRPB under the common clock mode are sufficiently stable for the ambiguity resolution. Compared with the traditional method, the ambiguity resolution success rate and positioning accuracy of the proposed method can be improved by 19.5% and 46.4% in the restricted satellite visibility environments.

scholarly journals GNSS SATELLITE VISIBILITY ANALYSIS BASED ON 3D SPATIAL INFORMATION IN URBAN AREAS

2020 ◽  
Vol XLIII-B4-2020 ◽  
pp. 123-128
Author(s):  
Y.-H. Lu ◽  
J.-Y. Han
Keyword(s):  
Spatial Data ◽  
Urban Areas ◽  
Spatial Information ◽  
Signal Transmission ◽  
Point Clouds ◽  
Satellite System ◽  
Topographic Effects ◽  
Analysis Technique ◽  
Satellite Visibility ◽  
Global Navigation Satellite

Abstract. Global Navigation Satellite System (GNSS) is a matured modern technique for spatial data acquisition. Its performance has a great correlation with GNSS receiver position. However, high-density building in urban areas causes signal obstructions and thus hinders GNSS’s serviceability. Consequently, GNSS positioning is weakened in urban areas, so deriving proper improvement resolutions is a necessity. Because topographic effects are considered the main factor that directly block signal transmission between satellites and receivers, this study integrated aerial borne LiDAR point clouds and a 2D building boundary map to provide reliable 3D spatial information to analyze topographic effects. Using such vector data not only reflected high-quality GNSS satellite visibility calculations, but also significantly reduced data amount and processing time. A signal obstruction analysis technique and optimized computational algorithm were also introduced. In conclusion, this paper proposes using superimposed column method to analyze GNSS receivers’ surrounding environments and thus improve GNSS satellite visibility predictions in an efficient and reliable manner.

scholarly journals Satellite Availability and Service Performance Evaluation for Next-Generation GNSS, RNSS and LEO Augmentation Constellation

2021 ◽  
Vol 13 (18) ◽  
pp. 3698
Author(s):  
Haomeng Cui ◽  
Shoujian Zhang
Keyword(s):  
Satellite System ◽  
Low Earth Orbit ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Next Generation ◽  
Satellite Systems ◽  
Satellite Visibility ◽  
Under Construction ◽  
Global Navigation Satellite ◽  
Average Position

Positioning accuracy is affected by the combined effect of user range errors and the geometric distribution of satellites. Dilution of precision (DOP) is defined as the geometric strength of visible satellites. DOP is calculated based on the satellite broadcast or precise ephemerides. However, because the modernization program of next-generation navigation satellite systems is still under construction, there is a lack of real ephemerides to assess the performance of next-generation constellations. Without requiring real ephemerides, we describe a method to estimate satellite visibility and DOP. The improvement of four next-generation Global Navigation Satellite Systems (four-GNSS-NG), compared to the navigation constellations that are currently in operation (four-GNSS), is statistically analyzed. The augmentation of the full constellation the Quasi-Zenith Satellite System (7-QZSS) and the Navigation with Indian Constellation (11-NavIC) for regional users and the low Earth orbit (LEO) constellation enhancing four-GNSS performance are also analyzed based on this method. The results indicate that the average number visible satellites of the four-GNSS-NG will reach 44.86, and the average geometry DOP (GDOP) will be 1.19, which is an improvement of 17.3% and 7.8%, respectively. With the augmentation of the 120-satellite mixed-orbit LEO constellation, the multi-GNSS visible satellites will increase by 5 to 8 at all latitudes, while the GDOP will be reduced by 6.2% on average. Adding 7-QZSS and 11-NavIC to the four-GNSS-NG, 37.51 to 71.58 satellites are available on global scales. The average position DOP (PDOP), horizontal DOP (HDOP), vertical DOP (VDOP), and time DOP (TDOP) are reduced to 0.82, 0.46, 0.67 and 0.44, respectively.

scholarly journals A Quad-Constellation GNSS Navigation Algorithm with Colored Noise Mitigation

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5563
Author(s):  
Xianqiang Cui ◽  
Tianhang Gao ◽  
Changsheng Cai
Keyword(s):  
Global Navigation Satellite System ◽  
Colored Noise ◽  
Satellite System ◽  
Navigation Satellite ◽  
Noise Mitigation ◽  
Positioning Accuracy ◽  
Navigation Algorithm ◽  
Satellite Visibility ◽  
Global Navigation ◽  
Global Navigation Satellite

The existence of colored noise in kinematic positioning will greatly degrade the accuracy of position solutions. This paper proposes a Kalman filter-based quad-constellation global navigation satellite system (GNSS) navigation algorithm with colored noise mitigation. In this algorithm, the observation colored noise and state colored noise models are established by utilizing their residuals in the past epochs, and then the colored noise is predicted using the models for mitigation in the current epoch in the integrated Global Positioning System (GPS)/GLObal NAvigation Satellite System (GLONASS)/BeiDou Navigation Satellite System (BDS)/Galileo navigation. Kinematic single point positioning (SPP) experiments under different satellite visibility conditions and road patterns are conducted to evaluate the effect of colored noise on the positioning accuracy for the quad-constellation combined navigation. Experiment results show that the colored noise model can fit the colored noise more effectively in the case of good satellite visibility. As a result, the positioning accuracy improvement is more significant after handling the colored noise. The three-dimensional positioning accuracy can be improved by 25.1%. Different satellite elevation cut-off angles of 10º, 20º and 30º are set to simulate different satellite visibility situations. Results indicate that the colored noise is decreased with the increment of the elevation cut-off angle. Consequently, the improvement of the SPP accuracy after handling the colored noise is gradually reduced from 27.3% to 16.6%. In the cases of straight and curved roads, the quad-constellation GNSS-SPP accuracy can be improved by 22.1% and 25.7% after taking the colored noise into account. The colored noise can be well-modeled and mitigated in both the straight and curved road conditions.

Positioning stability improvement with inter-system biases on multi-GNSS PPP

2018 ◽  
Vol 12 (3) ◽  
pp. 239-248 ◽  
Author(s):  
Byung-Kyu Choi ◽  
Hasu Yoon
Keyword(s):  
Precise Point Positioning ◽  
Elevation Angle ◽  
Satellite System ◽  
Comprehensive Analysis ◽  
Convergence Time ◽  
Dual Frequency ◽  
Position Accuracy ◽  
Satellite Visibility ◽  
Global Navigation Satellite ◽  
Accuracy And Stability

Abstract The availability of multiple signals from different Global Navigation Satellite System (GNSS) constellations provides opportunities for improving positioning accuracy and initial convergence time. With dual-frequency observations from the four constellations (GPS, GLONASS, Galileo, and BeiDou), it is possible to investigate combined GNSS precise point positioning (PPP) accuracy and stability. The differences between GNSS systems result in inter-system biases (ISBs). We consider several ISB values such as GPS-GLONASS, GPS-Galileo, and GPS-BeiDou. These biases are compliant with key parameters defined in the multi-GNSS PPP processing. In this study, we present a unified PPP method that sets ISB values as fixed or constant. A comprehensive analysis that includes satellite visibility, position dilution of precision, position accuracy is performed to evaluate a unified PPP method with constrained cut-off elevation angles. Compared to the conventional PPP solutions, our approach shows more stable positioning at a constrained cut-off elevation angle of 50 degrees.

Performance Analysis of GPS/GLONASS Precise Point Positioning

GEOMATICA ◽  
2013 ◽  
Vol 67 (4) ◽  
pp. 237-242 ◽  
Author(s):  
Mohamed Azab ◽  
Ahmed El-Rabbany ◽  
M. Nabil Shoukry ◽  
Ramadan Khalil ◽  
Akram Afifi
Keyword(s):  
Precise Point Positioning ◽  
Satellite System ◽  
Data Sets ◽  
Dual Frequency ◽  
International Gnss Service ◽  
Positioning Systems ◽  
Processing Strategies ◽  
Satellite Visibility ◽  
Point Positioning ◽  
Global Navigation Satellite

Precise Point Positioning (PPP) with Global Positioning Systems (GPS) has attracted the attention of many researchers over the past decade. Recently, the Russian global navigation satellite system (GLONASS) has been modernized and restored to near full constellation status, which has made it more attractive for positioning and navigation. Having two healthy systems, namely GPS and GLONASS provides a combination of both constellations, which in turn promises to improve the availability, positioning accuracy, and reliability of PPP solutions. This study investigates the effect of combining GPS and GLONASS dual-frequency measurements on the static PPP solution and its sensitivity to different processing strategies. Many data sets from five globally distributed International GNSS Service (IGS) tracking stations were processed using the Bernese GPS software package. The addition of GLONASS constellation improved the satellite visibility and geometry by more than 60%, and 40%, respectively, and improves the positioning convergence by up to 41%, 38%, and 19% in east, north, and up directions, respectively.

Loran-C in a European Navigation Perspective

1998 ◽  
Vol 51 (2) ◽  
pp. 243-249
Author(s):  
Börje Forssell
Keyword(s):  
Western Europe ◽  
Low Frequency ◽  
Time Frame ◽  
Satellite System ◽  
Satellite Systems ◽  
Satellite Navigation System ◽  
The North ◽  
Satellite Visibility ◽  
And Performance ◽  
The Baltic

After a brief overview of Loran-C system operation and performance, the present situation of the system in Europe is described. Loran-C is now in operation under the NELS agreement in north-western Europe in newly established chain configurations with old and new transmitter positions. Parallel to Loran-C the Russian equivalent, Chayka, is also operating, with three chains in Europe. There is an agreement between Norway and Russia concerning cooperation and possibly joint chain operations between the two system providers in the north; similar agreements in the Baltic and Mediterranean/Black Sea areas are being worked on. The situation around the Iberian peninsula has not yet been clarified. Being the only long/medium-range terrestrial system in Europe in the 2000+ time frame, Loran-C could be seen as a supplement to satellite systems. Due to the good penetration properties of its low-frequency signals, it can be used in many circumstances where satellite systems fail because of limited satellite visibility. Integration of Loran-C and (differential) satellite receivers, where Loran-C is calibrated by the satellite system as long as there are enough visible satellites, could in fact give the best of both worlds. For this reason, Loran-C is being considered in the perspective of a future international, civil satellite navigation system, initiated in Europe.

scholarly journals Extended Geometry and Probability Model for GNSS+ Constellation Performance Evaluation

2020 ◽  
Vol 12 (16) ◽  
pp. 2560
Author(s):  
Lingdong Meng ◽  
Jiexian Wang ◽  
Junping Chen ◽  
Bin Wang ◽  
Yize Zhang
Keyword(s):  
Probability Model ◽  
Satellite System ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Navigation Satellite ◽  
Constellation Design ◽  
Leo Satellites ◽  
Satellite Visibility ◽  
Global Navigation Satellite ◽  
Gnss Constellation

We proposed an extended geometry and probability model (EGAPM) to analyze the performance of various kinds of (Global Navigation Satellite System) GNSS+ constellation design scenarios in terms of satellite visibility and dilution of precision (DOP) et al. on global and regional scales. Different from conventional methods, requiring real or simulated satellite ephemerides, this new model only uses some basic parameters of one satellite constellation. Verified by the reference values derived from precise satellite ephemerides, the accuracy of visible satellite visibility estimation using EGAPM gets an accuracy better than 0.11 on average. Applying the EGAPM to evaluate the geometry distribution quality of the hybrid GNSS+ constellation, where highly eccentric orbits (HEO), quasi-zenith orbit (QZO), inclined geosynchronous orbit (IGSO), geostationary earth orbit (GEO), medium earth orbit (MEO), and also low earth orbit (LEO) satellites included, we analyze the overall performance quantities of different constellation configurations. Results show that QZO satellites perform slightly better in the Northern Hemisphere than IGSO satellites. HEO satellites can significantly improve constellation geometry distribution quality in the high latitude regions. With 5 HEO satellites included in the third-generation BeiDou navigation satellite system (BDS-3), the average VDOP (vertical DOP) of the 30° N–90° N region can be decreased by 16.65%, meanwhile satellite visibility can be increased by 38.76%. What is more, the inclusion of the polar LEO constellation can significantly improve GNSS service performance. When including with 288 LEO satellites, the overall DOPs (GDOP (geometric DOP), HDOP (horizontal DOP), PDOP (position DOP), TDOP (time DOP), and VDOP) are decreased by about 40%, and the satellite visibility can be increased by 183.99% relative to the Global Positioning System (GPS) constellation.

scholarly journals Complexity and Limitations of GNSS Signal Reception in Highly Obstructed Enviroments

2021 ◽  
Vol 11 (2) ◽  
pp. 6864-6868
Author(s):  
A. Hussain ◽  
F. Akhtar ◽  
Z. H. Khand ◽  
A. Rajput ◽  
Z. Shaukat
Keyword(s):  
Signal Strength ◽  
Satellite System ◽  
Statistical Characteristics ◽  
Navigation Systems ◽  
Path Delay ◽  
Range Measurements ◽  
Signal Characteristics ◽  
Satellite Visibility ◽  
Nlos Reception ◽  
Global Navigation Satellite

Multipath (MP) and/or Non Line-Of-Sight (NLOS) reception remains a potential vulnerability to satellite-based positioning and navigation systems in high multipath environments, such as an urban canyon. In such an environment, satellite signals are reflected, scattered or faded, and sometimes completely blocked by roofs and walls of high-rise buildings, fly-over bridges, complex road structures, etc. making positioning and navigation information inaccurate, unreliable, and largely unavailable. The magnitude of the positioning error depends on the satellite visibility, geometric distribution of satellites in the sky, and received signal quality and characteristics. The quality of the received signal (i.e. its statistical characteristics) can significantly vary in different environments and these variations can reflect in signal strength or power, range measurements (i.e. path delay and phase difference), and frequency, all of which distort the correlation curve between the received signal and receiver-generated replicas, resulting in range errors of tens of meters. Therefore, in order to meet stringent requirements defined for the Standard Positioning Service (SPS), the characterization of distortions that could significantly affect a Global Navigation Satellite System (GNSS) signal is essentially important. The scope of this paper is to detect possible imperfections/deviations in the GNSS signal characteristics that can occur due to MP or NLOS reception and analyze its effects. For this purpose, analysis of fading patterns in received signal strength (i.e. Carrier-to-Noise Ratio and strength fluctuations) is carried out in both clear LOS and high MP environment and then its impact on satellite lock state (i.e. tracking) is assessed. Furthermore, phase fluctuations and range residuals are computed to analyze the effects of path delays. The results show that significant variations can occur in GNSS signal characteristics in the MP environment that may result in loss of lock event and inaccurate/faulty range measurements.

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