Showing papers on "GNSS augmentation published in 2008"

Evolution of the Global Navigation SatelliteSystem (GNSS)

Abstract: The Global Navigation Satellite System (GNSS) is the worldwide set of satellite navigation constellations, civil aviation augmentations, and user equipment. This paper reviews the current status and future plans of the elements of GNSS as it pertains to civil aviation. The paper addresses the following satellite navigation systems: the U.S. Global Positioning System (GPS), Russian GLONASS, European Galileo, Chinese Compass, Japanese Quasi Zenith Satellite System, and Indian Regional Navigation Satellite System. The paper also describes aviation augmentations including aircraft-based, satellite-based, ground-based, and ground-based regional augmentation systems defined by the International Civil Aviation Organization. Lastly, this paper details typical user equipment configurations and civil aviation applications of GNSS including navigation, automatic dependent surveillance, terrain awareness warning systems, and timing.

ADOP in closed form for a hierarchy of multi-frequency single-baseline GNSS models

Abstract: Successful carrier phase ambiguity resolution is the key to high-precision positioning with Global Navigation Satellite Systems (GNSS). The ambiguity dilution of precision (ADOP) is a well-known scalar measure which can be used to infer the strength of the GNSS model for carrier phase ambiguity resolution. In this contribution we present analytical closed-form expressions for the ADOP. This will be done for a whole class of different multi- frequency single baseline models. These models include the geometry-fixed, the geometry-free and the geometry-based models, respectively. And within the class of geometry-based models, we discriminate between short and long observation time spans, and between stationary and moving receivers. The easy-to-use ADOP expressions can be applied to infer the contribution of various GNSS model factors. They comprise, for instance, the type, the number and the precision of the GNSS observations, the number and selection of frequencies, the presence of atmospheric disturbances, the length of the observation time span and the length of the baseline.

Global Positioning: Technologies and Performance

Abstract: Foreword. Acknowledgements. Preface. Chapter 1. A brief history of navigation and positioning. 1.1 The first age of navigation. 1.2 The age of the great navigators. 1.3 Cartography, lighthouses and astronomical positioning. 1.4 The radio age. 1.5 The first terrestrial positioning systems. 1.6 The era of artificial satellites. 1.7 Real-time satellite navigation constellations today. 1.8 Exercises. Bibliography. Chapter 2. A brief explanation of the early techniques of positioning. 2.1 Discovering the world. 2.2 The first age of navigation and the longitude problem. 2.3 The first optical based calculation techniques. 2.4 The first terrestrial radio based systems. 2.5 The first navigation satellite systems: TRANSIT and PARUS/TSIKADA. 2.6 The second generation of navigation satellite systems: GPS, GLONASS and Galileo. 2.7 The forthcoming third generation of navigation satellite systems: QZSS and COMPASS. 2.8 Representing the world. 2.9 Exercises. Bibliography Chapter 3. Development, deployment and current status of satellite based navigation systems. 3.1 Strategic, economical and political aspects. 3.2 The global positioning satellite systems: GPS, GLONASS and Galileo. 3.2.1 The Global Positioning System : GPS. 3.2.2 The GLONASS. 3.2.3 Galileo. 3.3 The GNSS1: EGNOS, WAAS and MSAS. 3.4 The other satellite based systems. 3.5 Differential satellite based commercial services. 3.6 Exercises. Bibliography. Chapter 4. Non-GNSS positioning systems and techniques for outdoors. 4.1 Introduction (large area without contact or wireless systems). 4.2 The optical systems. 4.3 The terrestrial radio systems. 4.4 The satellite radio systems. 4.5 Non-radio based systems. 4.6 Exercises. Bibliography. Chapter 5. GNSS system descriptions. 5.1 System description. 5.2 Summary and comparison of the three systems. 5.3 Basics of GNSS positioning parameters. 5.4 Introduction to error sources. 5.5 Concepts of differential approaches. 5.6 SBAS system description (WAAS and EGNOS). 5.7 Exercises. Bibliography. Chapter 6. GNSS navigation signals: description and details. 6.1 Navigation signal structures and modulations for GPS, GLONASS and Galileo. 6.2 Some explanations of the concepts and details of the codes. 6.3 Mathematical formulation of the signals. 6.4 Summary and comparison of the 3 systems. 6.5 Developments. 6.6 Error sources. 6.7 Time reference systems. 6.8 Exercises. Bibliography. Chapter 7. Acquisition and tracking of GNSS signals. 7.1 Transmission part. 7.2 Receiver architectures. 7.3 Measurement techniques. 7.4 Exercises. Bibliography. Chapter 8. Techniques for calculating positions. 8.1 Calculating the PVT solution. 8.2 Satellite's position computations. 8.3 Quantified estimation of errors. 8.4 Impact of pseudo range errors on the computed positioning. 8.5 Impact of geometrical distribution of satellites and receiver (notion of DOP). 8.6 Benefits of augmentation systems. 8.7 Discussion on interoperability and integrity. 8.8 Effect of multipath on the navigation solution. 8.9 Exercises. Bibliography. Chapter 9. Indoor positioning problem and main techniques (Non-GNSS). 9.1 General introduction to indoor positioning. 9.2 A brief review of possible techniques. 9.3 Network of sensors. 9.4 Local area telecommunication systems. 9.5 Wide-area telecommunication systems. 9.6 Inertial systems. 9.7 Recap tables and global comparisons. 9.8 Exercises. Bibliography. Chapter 10. GNSS-based indoor positioning and a summary of indoor techniques. 10.1 HS-GNSS. 10.2 A-GNSS. 10.3 Hybridization. 10.4 Pseudolites. 10.5 Repeaters. 10.6 Recap tables and comparisons. 10.7 Possible evolutions with availability of the future signals. 10.8 Exercises. Bibliography. Chapter 11. Applications of modern geographical positioning systems. 11.1 Introduction. 11.2 A chronological review of the past evolution of applications. 11.3 Individual applications. 11.4 Scientific applications. 11.5 Applications for public regulatory forces. 11.6 Systems under development. 11.7 Classifications of applications. 11.8 Privacy issues. 11.9 Current receivers and systems. 11.10 Conclusion and discussion. 11.11 Exercises. Bibliography. Chapter 12. The forthcoming revolution. 12.1 Time and space. 12.2 Development of current applications. 12.3 The possible revolution of everybody's daily life. 12.4 Possible technical positioning approaches and methods for the future. 12.5 Conclusion. 12.6 Exercises. Bibliography. Index.

Protection and fundamental vulnerability of GNSS

Abstract: An increasing number of mobile applications and services require that devices are aware of their location. Global navigation satellite systems (GNSS) are the predominant enabling technology. But location information provided by commercial GNSS is not secure, unlike what is the usual assumption. There are only few exceptions in the literature that present GNSS vulnerabilities. In this paper, we contribute the first detailed quantitative analysis of attacks against GNSS-based localization. We show how replay attacks against GNSS can have a significant impact: even against cryptographically secured GNSS instantiations, an adversary can manipulate the location and time calculated by victim GNSS receivers. We explain in detail how such attacks can be mounted, measure their impact, and discuss the effectiveness of possible countermeasures.

Non-GNSS radio frequency navigation

Abstract: There are many situations in which global navigation satellite systems (GNSS) such as the global positioning system (GPS) cannot provide adequate navigation performance (such as indoors or in urban canyons). This paper describes the technical challenges of non-GNSS radio frequency navigation, with particular emphasis on signals of opportunity (i.e., signals that are intended for purposes other than navigation). Advantages and disadvantages of signal of opportunity navigation are described, along with the dominant issues that must be dealt with in order to make such systems a practical reality.

Enhancement of global vehicle localization using navigable road maps and dead-reckoning

Abstract: This paper presents a data fusion strategy for the global localization of car-like vehicles. The system uses raw GNSS measurements, dead-reckoning sensors and road map data. We present a new method to use the map information as a heading observation in a Kalman filter. Experimental results show the benefit of such a method when the GPS information is not available. Then, we propose a conservative localization strategy that relies mainly on dead-reckoned navigation. The GNSS measurements and the map information are not used when consistency tests are doubtful. Experimental tests indicate that the performance is effectively better when using only the available consistent information.

Method of performing routing with artificial intelligence

Abstract: A method of performing routing in a global navigation satellite system (GNSS) navigation device incorporates user preferences determined through driving habits of the user. The GNSS navigation device stores a driving history, namely a plurality of route segments corresponding to maneuvers of a driver. The GNSS navigation device then determines which route segments of the plurality of route segments the user prefers based on the driving history. When generating a route, the GNSS navigation device then includes the preferred route segment.

Implementation and Operational Use of Ground-Based Augmentation Systems (GBASs)—A Component of the Future Air Traffic Management System

Abstract: This paper discusses a satellite navigation augmentation system designed for use by aviation. The ground-based augmentation system (GBAS) was originally developed as a precision approach and landing aid. This paper describes the GBAS concept, discusses the system architecture, and discusses ground and airborne equipment that compose the system. This paper also describes typical operational use of the system and the experience gained during early implementations. Advantages over the current instrument landing system technology are also discussed.

GNSS method and receiver with camera aid

Abstract: A method of computing navigation information in a portable device comprising a GNSS receiver arranged to receive navigation signals from a plurality of navigation satellites, and a GNSS processor to extract a GNSS position information from said navigation signals. The GNSS receiver is also arranged to obtain image data from a camera module. The method comprises the steps of: deriving a set of position information from the camera module; providing the camera-derived position information to a navigation processor; using said set of camera-derived position information and said navigation signals, to generate a position fix of the GNSS receiver; computing navigation information based on said generated position fix.

Investigation on the effect of strong out-of-band signals on global navigation satellite systems receivers

Abstract: The mitigation of radio frequency interference (RFI) has a fundamental role in global navigation satellite system (GNSS) applications, especially when a high level of availability is required. Several electromagnetic sources, in fact, might degrade the performance of the global positioning system (GPS) and Galileo receivers, and their effects can be either in-band (i.e., secondary harmonics generated by transmitters of other communication systems due to non-linearity distortions) or out-of-band (i.e., strong signals that occupy frequency bandwidths very close to GNSS bands). We investigated the effects of real out-of-band signals on GNSS receivers and analyzed the impact on the overall receiver chain in order to evaluate the impact of the interference source. In particular, the analysis focuses on the spectrum at the front-end output, on the automatic gain control (AGC) behavior, as well as on the digital processing stages (signal acquisition and tracking) at the analog digital converter (ADC) output. This study refers to several experiments and data collections performed in interfered areas of downtown Torino (Italy). The obtained results underline how digital/analog TV transmissions represent a potential interference source for GNSS applications and might be critical for the safety of life services.

Integrated dead reckoning and gnss/ins positioning

Abstract: An integrated dead reckoning (DR) and GNSS/INS control system and method are provided for guiding, navigating and controlling vehicles and equipment. A controller generally prioritizes GNSS navigation when satellite signals are available. Upon signal interruption, DR guidance can be integrated with INS to continue autosteering and other automated functions. Exemplary applications include logistics operations where ships, cranes and stacked containers can block satellite signals.

GNSS positioning using pressure sensors

Abstract: Systems, methods and devices for improving the accuracy of GNSS data are provided Specifically, embodiments of the invention can advantageously use sensor input to improve the accuracy of position fixes The use of physical 5 sensors in navigation systems is deemed particularly advantageous, especially where altitude data derived from the pressure sensor is calibrated with and/or blended with GNSS altitude data

Attitude estimation using intentional translation of a global navigation satellite system (GNSS) antenna

Abstract: A system determines three-dimensional attitude of a stationary or moving platform using signals from a Global Navigation Satellite System (GNSS) antenna that undergoes deliberate translation, which may be occasional. The system uses single GNSS receiver, a single GNSS antenna, and inertial acceleration and/or rotation rate sensors. In one implementation, the GNSS antenna and inertial sensing components are rigidly connected and mounted to a pallet that is intentionally translated along a track as needed. In a second implementation, the GNSS antenna is mounted to a pallet, and the inertial sensing components are fixed in position. To maximize effectiveness, the track is oriented along a geometrical direction of the platform that is predominantly in a lateral direction from the gravity vector. The system achieves three-dimensional attitude accuracy that rivals interferometric GNSS systems.

Thermal Calibration of Low Cost MEMS Sensors for Land Vehicle Navigation System

Abstract: For vehicle navigation, Global Positioning System (GPS) provides long term accurate positions, but only when direct lines of sight to four or more satellites exist. Inertial Navigation Systems (INS), on the other hand, are self contained sensors that can provide short term accurate navigation information. The integration of the two systems can effectively provide continuous navigation data even during GPS signal outages. Traditional inertial systems were heavy, bulky and costly. In the past two decades, the use and development of light weight, compact and cost effective Micro-Electro-Mechanical Systems (MEMS) based inertial sensors has made the civilian integrated vehicle navigation systems more affordable. However, these sensors still have to make their way in the field due to their significant error sources such as turn-on biases or scale factors variations. Moreover, the performance characteristics of these sensors are highly dependent on the environmental conditions such as temperature variations. Hence there is a need for the development of accurate, reliable and efficient thermal models to reduce the effect of these errors that can degrade the system performance.

Data and Pilot Combining for Composite GNSS Signal Acquisition

Abstract: With the advent of new global navigation satellite systems (GNSS), such as the European Galileo, the Chinese Compass and the modernized GPS, the presence of new modulations allows the use of special techniques specifically tailored to acquire and track the new signals. Of particular interest are the new composite GNSS signals that will consist of two different components, the data and pilot channels. Two strategies for the joint acquisition of the data and pilot components are compared. The first technique, noncoherent combining, is from the literature and it is used as a comparison term, whereas the analysis of the second one, coherent combining with sign recovery, represents the innovative contribution of this paper. Although the analysis is developed with respect to the Galileo E1 Open Service (OS) modulation, the obtained results are general and can be applied to other GNSS signals.

Formulation of a time-varying maximum allowable error for ground-based augmentation systems

Abstract: Ground-based augmentation systems (GBAS), such as the federal aviation administration's local area augmentation system (LAAS), protect GPS users against signal anomalies by monitoring for rare satellite faults. This paper introduces a new, time-varying MERR (maximum-allowable error in range) formulation that enables proof of integrity for ground-based fault monitoring. The time-varying MERR supersedes earlier MERR methods which relied on a static integrity test. The utility of these earlier methods was limited in that they neglected GBAS time-to-alert (TTA) requirements and restricted the choice of the monitor filter, requiring its impulse response to match that of the user ranging-error filter. By contrast, the time-varying MERR explicitly incorporates TTA and places no restrictions on monitor filter design. These attributes are critical for correctly evaluating system integrity and for crediting the integrity benefits of GBAS systems with aggressive filter designs and process timing.

Location systems for handheld electronic devices

Abstract: An electronic device such as a portable electronic device is provided. The device may have wireless circuitry such as a global satellite navigation system receiver for receiving global satellite navigation system signals and for producing corresponding global satellite navigation system data. The global satellite navigation system data may include information on the current position of the portable electronic device. The portable electronic device may also have one or more sensors that are used to gather data in addition to the global satellite navigation system data. The sensors may include accelerometers and other devices capable of determining how the portable electronic device is oriented with respect to the Earth's magnetic field and how the device is being moved. When the device is moved, the movement and resulting change in orientation may be used in conjunction with the global satellite navigation system data to compute a current geographic location.

Power saving method adaptable in GNSS device

Abstract: A method and system for navigation are provided to locate a GNSS device. The GNSS device comprises a RF front end receiving satellite signals of a plurality of satellites, and a GNSS device comprising a plurality of correlation channels each performing a correlation process to generate a correlation result from satellite signals corresponding to a satellite, a memory device for storage of the correlation results, and a processor performing acquisition and tracking based on the correlation results.

Multi‐constellation GNSS/RNSS from the perspective of high accuracy users in Australia

Abstract: Global Navigation Satellite Systems (GNSSs) involve satellites, ground stations and user equipment, and are now used to support many activities within modern societies. The U.S. Global Positioning System (GPS) is the best known, and only currently fully operational GNSS. Russia also operates its own (not yet fully deployed) GNSS called GLONASS. Fuelling growth in applications during the next decade will be next generation GNSSs that are currently being developed and deployed. Next generation GNSSs will include the U.S.’s modernized GPS and planned GPS‐III, Russia's revitalised GLONASS, Europe's GALILEO system, and China's planned COMPASS system. Furthermore, a number of Space Based Augmentation Systems (SBASs) and Regional Navigation Satellite Systems (RNSSs) will add extra satellites and signals to the multi‐constellation GNSS/RNSS ‘mix’. How will this proliferation of satellites and signals impact on the spatial information disciplines? Is the concept of a ‘system of systems’ receiver, and associated gr...

Gnss receiver and external storage device system and gnss data processing method

Abstract: A GNSS system includes a receiver connected to an external mass storage device. Applications for the system, including GNSS data processing methods are also disclosed. The external storage device can comprise a flash (thumb) drive, which can be connected to the receiver via a USB interconnection.

Future Architectures to Provide Aviation Integrity

Abstract: Ionospheric delay uncertainty creates the largest restriction to the availability of high integrity satellite navigation for today’s single frequency systems. LAAS, WAAS, and the other SBAS providers are limited in their coverage and service levels by the variability of the ionosphere. With the arrival of the new civil signals at L5, comes the ability to directly estimate and remove the ionospheric delay at any point on the Earth. This allows for new architectures exploiting L1 and L5 to bring airplanes within two hundred feet of the ground anywhere on the globe. The FAA has initiated a study panel, called the GPS Evolutionary Architectural Study (GEAS) to look into future architectures to provide this global service. The GEAS has determined that Time-to-Alert (TTA) will be one of the more difficult challenges for any global monitoring approach. To address this problem, the GEAS is looking at two methods, each of which transfers some of the TTA responsibility onto the aircraft. The first method is called Relative RAIM (RRAIM). It uses precise carrier phase measurements to propagate older code based position solutions forward in time. The veracity of the propagation is checked using RAIM on the very low noise carrier phase measurements. In this way, the overall TTA can be less than a second, but the ground is given tens of seconds to minutes to identify a fault. The second method is Absolute RAIM (ARAIM). This is more similar to existing FDE techniques except that the requirements must be made much more precise in order to support smaller alert limits. Again, the aircraft is able to raise a flag within seconds of receiving faulty data. The ground is allowed to take an hour or longer to identify the fault and remove it from future consideration. The protection level equations for both methods will be evaluated in this paper. In addition to the errors considered in today’s equations, the two new methods will include explicit bias terms to improve the handling of nominal biases and non-gaussian error sources. A critical parameter in the performance of these approaches is the strength of the constellation. The performance of each is evaluated for constellations optimized for 24, 27, and 30 satellites. Further, their performance is evaluated under conditions of satellite outages. RRAIM can perform very well with fewer satellites. ARAIM on the other hand is ideal for integrating in Galileo or other satellite constellations. Both of the methods show great promise for global provision of vertical guidance.

GNSS Offline Signal Quality Assessment

Abstract: This paper deals with the offline measurement of instantaneous frequency transfer distortions and its impact to navigation performance. Distortions on the frequency transfer-characteristics are relevant for users mainly via reductions of usable signal power and due to biases which are difficult to be removed. For characterisation of distortion effects for real satellites and navigation receivers, several evaluation parameters are introduced, which are based on the offline processing of recorded base-band samples. Typical communication system related parameters are considered (like PSD, scatter-plot and eye-diagram) but also parameters which are derived from the correlation function shape and thus show directly the distortion-impact on navigation performance. The latter class of parameters comply correlation-loss, S-curve-bias, code-code-coherency and the frequency transfer characteristic itself. Accurate measurements of frequency transfer distortions require careful consideration of measurement distortions. This complies at least measurement noise, sampling constraints and as most critical the calibration/equalisation of the measurement frequency transfer characteristics. For measurements with the satellite in orbit addionally care needs to be taken on multipath and interference, whereas the ionospheric dispersion reveals to be more harmless. These topics are discussed and some quantitative assessment results are given. As coarse conclusion, the reliable characterisation of satellites in orbit requires the use of high-gain-antennas (>20m diameter). Corresponding measurement setups with BaySEF connected to the DLR measurement setup using the 30 m - Weilheim antenna of DLR GSOC in Weilheim/Lichtenau, and with the 25-m dish in Chilbolton are shown, which were used for example measurements on the GIOVE-B satellite. Example offline signal quality assessment results for the various parameters and for the different signal transmissions in L1 from the early GIOVE-B in orbit tests (with BOC(1,1), with CBOC and with TMBOC) are presented, with the intention to test the evaluation methods rather than to assess the satellite. The results demonstrate the absolute qualification of applied evalation methods and will animate curious people to further assessments and analysis. For instance this concerns the conclusions, that can be drawn from certain evaluation parameter distortions. Future improvements derived from this activity for signal quality assessment are related to small refinements on evaluation parameters and mainly on the full control over accurate measurement system characterisation and calibration

The Potential Impact of GNSS/INS Integration on Maritime Navigation

Abstract: A version of this paper was presented at ENC-GNSS 2007, Geneva. Its reproduction was kindly authorised by the ENC-GNSS 07 Paper Selection Committee.The General Lighthouse Authorities of the UK & Ireland commissioned an assessment of the impact that the integration of Global Navigation Satellite Systems (GNSS) with Inertial Navigation Systems (INS) would have on the aids to navigation (AtoN) services currently provided, and those to be provided in the future. There is concern about the vulnerability of GNSS, and the provision of complementary and backup systems is seen to be of great importance. The integration of INS could provide an independent and self-contained navigation system, for a limited time period, invulnerable to external intentional or unintentional interference, or the influences of changes in national policies. The study included an analysis of the potential use of GNSS-INS in three of the four phases of a vessel's voyage: coastal, port approach and docking. The project consisted of a technology assessment, looking at the different inertial technologies that might be suitable for each phase. This was followed by a technology proving stage, evaluating suitable equipment using simulation and field trials to prove that the claimed performance could be achieved in practice. The final stage of the project was to assess the effects of the availability of such systems on existing and planned aids to navigation services.

Evaluation of a FFT-Based Acquisition in Real Time Hardware and Software GNSS Receivers

Abstract: The first step of the digital processing within a Global Navigation Satellite System (GNSS) receiver is the signal acquisition. The receiver has to detect the satellites in view, and for each of them, has to estimate the Doppler shift and the code phase of the received signal. In order to speed up the acquisition process, modern receivers use fast acquisition technique based on the Fast Fourier Transform (FFT). This paper presents the complexity evaluation of a FFT-based acquisition technique, suitable for new GNSS signals and for both software and hardware implementations. After the description of the algorithm, the focus will be on the comparison of the results obtained with a Xilinx FPGA board and a software receiver implemented on a general-purpose processor.

Extreme ionospheric conditions over Europe observed during the last solar cycle

Abstract: The extreme variability of the ionosphere poses a threat to GNSS applications, since the signals of Global Navigation Satellite Systems (GNSS) are influenced by the ionospheric plasma. In this paper we perform a review of ionospheric conditions over Europe using data from the past nine years covering almost the entire solar cycle. We are focusing on parameters important for GNSS applications, such as ionospheric spatial and temporal gradients. In order to obtain ionospheric gradient information we use both, the total electron content (TEC) rate of change and the differences of calibrated vertical TEC data at the same time. The deduced gradient information is used in order to generate probability density functions. We analyse singular extreme events and investigate correlations between the occurrence of large gradients and geo-physical parameters. Using the November 20, 2003 storm we discuss the potential of TEC gradients for contributing to a meaningful ionospheric perturbation index. Ionosphere signal delay is one of the major contributors to pseudo range residual error for both absolute positioning and for relative positioning, e.g., in the context of ground-based augmentation systems (GBAS). Our large data set is used in order to generate a generalized model of an instantaneous covariance matrix. The results are compared with a standard covariance matrix and conclusions on its applicability to positioning algorithms will be drawn.

System and method for intelligent tuning of kalman filters for ins/gps navigation applications

Abstract: Disclosed is a reinforcement learning technique for online tuning of integration filters of navigation systems needing a priori tuning parameters, such as Kalman Filters and the like. The method includes receiving GNSS measurements from the GNSS unit of the navigation system; and IMU measurements from IMU of the navigation system. The method further includes providing a priori tuning parameters to tune the integration filter of the navigation system. The method further includes processing the GNSS and IMU measurements using the tuned integration filter to compute a position estimate and updating the a priori turning parameters based on the computer position estimate.

e-Navigation and the Case for eLoran

Abstract: International discussions on the concept of e-navigation have identified a robust position-fixing system as one of the essential components. Global Navigation Satellite Systems (GNSS) are known to have vulnerabilities and onboard alternatives such as inertial systems have limitations. This paper considers the case for an enhanced version of the terrestrial radio-navigation system Loran to provide an alternative with performance comparable to GNSS. The paper reviews recent studies of inertial navigation systems and concludes that they do not present a fully capable backup to GNSS at present. Trials of enhanced Loran carried out in the UK by the General Lighthouse Authorities have shown that eLoran does have the potential to provide equivalent performance to GNSS over long periods and is a fully complementary system. The steps needed to provide eLoran on at least a regional basis, covering critical waterways, are considered. The international process for the specification and standardisation of eLoran is already underway and some projections are made about the timescale for full implementation, in the context of the introduction of e-Navigation. A version of this paper was first presented at NAV 07 held in Church House, London from 30th October – 1st November 2007.

Position error bound calculation for GNSS using measurement residuals

Abstract: In safety-of-life applications of satellite navigation, the protection level (PL) equation translates what is known about the pseudo-range errors into a reliable limit on the positioning error. The current PL equations for satellite-based augmentation systems (SBAS) rely on Gaussian statistics. This approach is very practical: the calculations are simple and the receiver computation load is small. However, when the true distributions are far from Gaussian, such a characterization forces an inflation of the PLs that degrades performance. This happens in particular with errors with heavy tail distributions or for which there is not enough data to evaluate the distribution density up to small quantiles. We present a way of computing the optimal protection level when the pseudo-range errors are characterized by a mixture of Gaussian modes. First, we show that this error characterization adds a new flexibility and helps account for heavy tails without losing the benefit of tight core distributions. Then, we state the positioning problem using a Bayesian approach. Finally, we apply this method to PL calculations for the wide area augmentation system (WAAS) using real data from WAAS receivers. The results are very promising: vertical PLs are reduced by 50% without degrading integrity.

System and method for use of a vehicle back-up camera as a dead-reckoning sensor

Abstract: Systems and methods are disclosed herein to use a vehicle back-up camera as a cost-effective dead-reckoning sensor in satellite-based vehicle navigation systems. Since the back-up camera may already use a display of the navigation system for display, the data from the back-up camera may be easily obtained and integrated into the navigation system. The data from the camera is received by a navigation receiver wirelessly or through a wired connection. The image is processed to determine the speed, heading, turn-rate of the vehicle to aid the satellite-based navigation system if the satellite signals are inadequate. Thus, enhanced vehicle navigation- performance can be obtained without adding new sensors and/or connecting to a vehicle data bus.