The Status, Development and Future Role of Radiobeacon Differential GNSS

1998 ◽  
Vol 51 (2) ◽  
pp. 152-158 ◽  
Author(s):  
N. Ward
Keyword(s):  
Global Navigation Satellite Systems ◽  
Current Status ◽  
Automatic Identification ◽  
Future Role ◽  
Satellite Systems ◽  
Advantages And Disadvantages ◽  
The Status ◽  
Differential Corrections ◽  
Global Navigation Satellite

Marine radiobeacons have been used to broadcast differential corrections for global navigation satellite systems (DGNSS) for nearly a decade. The method has become the accepted international standard for maritime applications. The background to the development of the system is described and the current status of radiobeacon DGNSS services around the world reported. The applications are discussed, including the function of radiobeacon DGNSS as the position sensor within integrated systems, together with the performance requirements imposed by associated systems such as ECDIS and Automatic Identification Systems. The advantages and disadvantages of the radiobeacon system in regulatory, administrative and technical terms are discussed and the potential for development of the system is considered. The future role of radiobeacon DGNSS in the overall mix of systems is assessed taking into account the introduction of geo-stationary overlays, and possibly Loran-C, for provision of DGNSS corrections.

scholarly journals GNSS RTK Positioning Augmented with Large LEO Constellation

2019 ◽  
Vol 11 (3) ◽  
pp. 228 ◽  
Author(s):  
Xingxing Li ◽  
Hongbo Lv ◽  
Fujian Ma ◽  
Xin Li ◽  
Jinghui Liu ◽  
...  
Keyword(s):  
Low Earth Orbit ◽  
Global Navigation Satellite Systems ◽  
Convergence Time ◽  
Current Status ◽  
Initial Assessment ◽  
Satellite Systems ◽  
Long Baseline ◽  
Leo Satellites ◽  
Global Navigation Satellite ◽  
Long Baselines

It is widely known that in real-time kinematic (RTK) solution, the convergence and ambiguity-fixed speeds are critical requirements to achieve centimeter-level positioning, especially in medium-to-long baselines. Recently, the current status of the global navigation satellite systems (GNSS) can be improved by employing low earth orbit (LEO) satellites. In this study, an initial assessment is applied for LEO constellations augmented GNSS RTK positioning, where four designed LEO constellations with different satellite numbers, as well as the nominal GPS constellation, are simulated and adopted for analysis. In terms of aforementioned constellations solutions, the statistical results of a 68.7-km baseline show that when introducing 60, 96, 192, and 288 polar-orbiting LEO constellations, the RTK convergence time can be shortened from 4.94 to 2.73, 1.47, 0.92, and 0.73 min, respectively. In addition, the average time to first fix (TTFF) can be decreased from 7.28 to 3.33, 2.38, 1.22, and 0.87 min, respectively. Meanwhile, further improvements could be satisfied in several elements such as corresponding fixing ratio, number of visible satellites, position dilution of precision (PDOP) and baseline solution precision. Furthermore, the performance of the combined GPS/LEO RTK is evaluated over various-length baselines, based on convergence time and TTFF. The research findings show that the medium-to-long baseline schemes confirm that LEO satellites do helpfully obtain faster convergence and fixing, especially in the case of long baselines, using large LEO constellations, subsequently, the average TTFF for long baselines has a substantial shortened about 90%, in other words from 12 to 2 min approximately by combining with the larger LEO constellation of 192 or 288 satellites. It is interesting to denote that similar improvements can be observed from the convergence time.

Enabling innovation through geodetic technologies: a provincial perspective

GEOMATICA ◽  
2016 ◽  
Vol 70 (3) ◽  
pp. 181-186
Author(s):  
Jason Bond
Keyword(s):  
Economic Benefits ◽  
Global Navigation Satellite Systems ◽  
Position Information ◽  
Satellite Systems ◽  
The Past ◽  
The Earth ◽  
Decision Making Processes ◽  
Global Navigation Satellite ◽  
Provided Examples

Geodetic technologies enable the measurement of the size, shape and orientation of the Earth, as well as the variation of these parameters over time. Advances in geodetic technology over the past few decades, particularly relating to Global Navigation Satellite Systems (GNSS), have made access to real-time centimetre-level positioning accuracy commonplace. As spatial position information becomes more critical to human and artificial intelligence decision-making processes, innovation has ensued to leverage that information. A review of key advances in geodetic technology is provided. Examples of innovations that leverage these technologies are presented. It is concluded that the role of geodetic infrastructure will become increasingly important as the backbone for other innovations and that jurisdictions investing resources in this area will be more likely to realize the potential economic benefits and operational efficiencies it creates.

scholarly journals Worldwide Availability of Maritime Medium-Frequency Radio Infrastructure for R-Mode-Supported Navigation

2020 ◽  
Vol 8 (3) ◽  
pp. 209 ◽  
Author(s):  
Paul Koch ◽  
Stefan Gewies
Keyword(s):  
Service Area ◽  
Global Navigation Satellite Systems ◽  
Automatic Identification ◽  
Identification System ◽  
Satellite Systems ◽  
Class A ◽  
Maritime Traffic ◽  
Global Navigation Satellite ◽  
Good Coverage ◽  
Radio Beacon

The Ranging Mode (R-Mode), a maritime terrestrial navigation system under development, is a promising approach to increase the resilient provision of position, navigation and timing (PNT) information for bridge instruments, which rely on Global Navigation Satellite Systems (GNSS). The R-Mode utilizes existing maritime radio infrastructure such as marine radio beacons, which support maritime traffic with more reliable and accurate PNT data in areas with challenging conditions. This paper analyzes the potential service, which the R-Mode could provide to the mariner if worldwide radio beacons were upgraded to broadcast R-Mode signals. The authors assumed for this study that the R-Mode is available in the service area of the 357 operational radio beacons. The comparison with the maritime traffic, which was generated from a one-day worldwide Automatic Identification System (AIS) Class A dataset, showed that on average, 67% of ships would operate in a global R-Mode service area, 40% of ships would see at least three and 25% of ships would see at least four radio beacons at a time. This means that R-Mode would support 25% to 40% of all ships with position and 67% of all ships with PNT integrity information. The relatively high number of supported ships compared to the total radio beacon coverage of about 9% of the earth’s surface is caused by the good coverage of busy ports and areas such as the coast of China, North Sea and Baltic Sea. These numbers emphasize the importance of marine radio beacons for the R-Mode system.

scholarly journals Commission 31: Time: (L’Heure)

2000 ◽  
Vol 24 (1) ◽  
pp. 60-63
Author(s):  
T. Fukushima ◽  
G. Petit ◽  
D.C. Backer ◽  
G. Beutler ◽  
V.A. Brumberg ◽  
...  
Keyword(s):  
Present Form ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Advantages And Disadvantages ◽  
Frequency Standards ◽  
Mise En Pratique ◽  
Definition Of ◽  
Primary Frequency ◽  
Global Navigation Satellite

The CCTF (formerly named CCDS) held its 14th meeting on 20-22 April 1999. Following the discussions, seven Recommendations were adopted and submitted to the Comité International des Poids et Mesures (CIPM). The list is the following: 1. Recommendation S 1 (1999): Mise-en-pratique of the definition of the second.2. Recommendation S 2 (1999): On stating uncertainty in comparisons involving primary frequency standards.3. Recommendation S 3 (1999): On the comparison of primary frequency standards.4. Recommendation S 4 (1999): On the use of multi-channel and multi-code GPS and GLONASS time receivers.5. Recommendation S 5 (1999): Time and frequency comparisons using GPS phase and code measurements.6. Recommendation S 6 (1999): Future global navigation satellite systems.7. Recommendation S 7 (1999): On Two-Way Satellite Time and Frequency TransferAdditionally discussed were the present form of UTC and mostly the interest of preserving the leap second. The advantages and disadvantages of several options regarding the future use of leap seconds were compared. The CCTF, however, felt that it did not have the authority to propose any action. Then CCTF decided to ask the BIPM Director to write to the relating international bodies including IAU so as to draw their attentions to this issue while recommending the usage of TAI in case a time scale without discontinuity is needed. Also it was decided, in order to make more expedite the process, to ask the opinions of the various Commissions of the Scientific Unions.

scholarly journals Ionospheric Gradient Threat Mitigation in Future Dual Frequency GBAS

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Michael Felux ◽  
Mihaela-Simona Circiu ◽  
Jiyun Lee ◽  
Florian Holzapfel
Keyword(s):  
Global Navigation Satellite Systems ◽  
Single Frequency ◽  
Dual Frequency ◽  
Satellite Systems ◽  
Gps Satellites ◽  
Ionospheric Gradients ◽  
Threat Mitigation ◽  
Differential Corrections ◽  
Position Solution ◽  
Global Navigation Satellite

The Ground Based Augmentation System (GBAS) is a landing system for aircraft based on differential corrections for the signals of Global Navigation Satellite Systems (GNSS), such as GPS or Galileo. The main impact on the availability of current single frequency systems results from the necessary protection against ionospheric gradients. With the introduction of Galileo and the latest generation of GPS satellites, a second frequency is available for aeronautical navigation. Dual frequency methods allow forming of ionospheric free combinations of the signals, eliminating a large part of the ionospheric threats to GBAS. However, the combination of several signals increases the noise in the position solution and in the calculation of error bounds. We, therefore, developed a method to base positioning algorithms on single frequency measurements and use the second frequency only for monitoring purposes. In this paper, we describe a detailed derivation of the monitoring scheme and discuss its implications for the use in an aviation context.

scholarly journals Optical clock technologies for global navigation satellite systems

GPS Solutions ◽  
2021 ◽  
Vol 25 (3) ◽  
Author(s):  
Thilo Schuldt ◽  
Martin Gohlke ◽  
Markus Oswald ◽  
Jan Wüst ◽  
Tim Blomberg ◽  
...  
Keyword(s):  
Molecular Iodine ◽  
Optical Clock ◽  
Global Navigation Satellite Systems ◽  
Current Status ◽  
Optical Frequency ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Satellite Links ◽  
Global Navigation ◽  
Global Navigation Satellite

AbstractFuture generations of global navigation satellite systems (GNSSs) can benefit from optical technologies. Especially optical clocks could back-up or replace the currently used microwave clocks, having the potential to improve GNSS position determination enabled by their lower frequency instabilities. Furthermore, optical clock technologies—in combination with optical inter-satellite links—enable new GNSS architectures, e.g., by synchronization of distant optical frequency references within the constellation using time and frequency transfer techniques. Optical frequency references based on Doppler-free spectroscopy of molecular iodine are seen as a promising candidate for a future GNSS optical clock. Compact and ruggedized setups have been developed, showing frequency instabilities at the 10–15 level for averaging times between 1 s and 10,000 s. We introduce optical clock technologies for applications in future GNSS and present the current status of our developments of iodine-based optical frequency references.

Open Source GNSS Reference Server for Assisted-Global Navigation Satellite Systems

2010 ◽  
Vol 64 (1) ◽  
pp. 127-139 ◽  
Author(s):  
Binghao Li ◽  
Jiahuang Zhang ◽  
Andrew G. Dempster ◽  
Chris Rizos
Keyword(s):  
Open Source ◽  
Global Navigation Satellite Systems ◽  
Current Status ◽  
Personal Digital Assistants ◽  
Navigation Satellite ◽  
Positioning Systems ◽  
Satellite Systems ◽  
Global Navigation ◽  
Global Navigation Satellite ◽  
Interface Protocol

Assisted-Global Navigation Satellite Systems (A-GNSS), or Assisted-Global Positioning Systems (A-GPS) in particular, are now commonly accepted as an effective way to reduce the time-to-first-fix (TTFF) in GNSS-unfriendly environments, e.g. in areas of weak GNSS signals. Today's location-based service (LBS) devices such as GPS-enabled mobile phones and personal digital assistants (PDA) rely on A-GPS; however, such commercial devices are equipped with an integrated A-GPS chip that makes customisation very difficult. The Open Source GNSS Reference Server (OSGRS) provided by the University of New South Wales is an open source Java application that can generate the necessary data for A-GPS clients. The GNSS Reference Interface Protocol (GRIP), based on extensible mark-up language (XML), is employed as the OSGRS interface protocol. This paper describes the current status of OSGRS: a client simulator is available open-source; client software which supports four different types of A-GPS-enabled receivers has been developed and used to test OSGRS. The performance of the OSGRS is analysed based on intensive tests. The challenges for OSGRS and future work are also discussed.

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