This paper proposes an airborne transceiver system as an alternative navigation system and a triangulation method using bidirectional range measurements as a method of transceiver position determination. We suggest several system arrays that can estimate each mobile transceiver position in real time. We found that our suggested alternative navigation system working in a 700 km×900 km region is feasible using only 10 transceivers at an altitude of 42 km, furthermore its performance can compete with that of Galileo's Open Service. This paper will contribute to the establishment of an alternative or backup navigation system with modest expenditure and a short development period, and which is independent of GPS.

SESAR is Europe's ‘Single European Sky Air traffic Research system’. NextGen is the USA's ‘Next Generation Air Transport System’. SESAR and NextGen are developments targeted at post 2020. The common vision is to integrate and implement new technologies to improve air traffic management (ATM) performance – a ‘new paradigm’. SESAR and NextGen combine increased automation with new procedures to achieve safety, economic, capacity, environmental, and security benefits. The systems do not have to be identical, but must have aligned requirements for equipment standards and technical interoperability.

A key component is a ‘cooperative surveillance’ model, where aircraft are constantly transmitting their position (from navigational satellites), flight path intent, and other useful aircraft parameters – known as ADS-B (Automatic Dependent Surveillance-Broadcast). The focus for planning and executing system operations will increasingly be aircraft 4D trajectories: a 4D trajectory is the aircraft path, three space dimensions plus time, from gate-to-gate, i.e. including the path along the ground at the airport.

In analysing potential major ATM system changes, a simple division into five Key Test areas might be: Safety Credibility, Operational Concept, Technological Feasibility, Benefits and Costs, and Transition Path. The main attention here is on Benefits and Costs of SESAR. The strategic challenge will be to convince customers and stakeholders of the benefits of paradigm shift expenditure, given the associated impacts on future user charges, aircraft equipment investments and public expenditure. The analysis here shows that the existing cost benefit analysis results for SESAR are not particularly robust, possibly over-estimating Net Present Values by some tens of € billions.

Real-time and near real-time precise GPS positioning requires shorter GPS solution convergence time. Residual tropospheric delay, which exists as a result of the limitations of existing tropospheric correction models, is a limiting factor for quick GPS solution convergence. This paper proposes a new approach to tropospheric delay modelling, which overcomes the limitations of existing models. In this approach, the bulk of the tropospheric delay is accounted for using the NOAA-generated tropospheric correction model, while the residual tropospheric delay component is accounted for stochastically. First, the NOAA tropospheric correction model is used to generate daily time series of zenith total tropospheric delays (ZTDs) at ten IGS reference stations spanning North America for many days in 2006. The NOAA ZTDs are then compared with the new highly-accurate IGS tropospheric delay product to obtain daily residual time series at 5 minute intervals. Finally, the auto-covariance functions of the daily residual tropospheric delay series are estimated at each of the ten reference stations and then used to find the best empirical covariance function in the least squares sense. Of the three potential covariance functions examined, it is shown that the exponential cosine function gives the best fit most of the time, while the second-order Gauss-Markov model gives the worst fit. The first-order Gauss-Markov fits are close to those of the exponential cosine. Additionally, the model coefficients seem to be season independent, but change with geographical location.

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.

The E5/L5 frequency band for the new Global Navigation Satellite System (GNSS) signals is crowded with aeronautical pulsed emitters. This results in severe degradation of the performance of GNSS receivers. This paper describes a novel technique for estimating and suppressing time-varying pulsed interference signals such as the Distance Measuring Equipment (DME)/Tactical Air Navigation (TACAN) signals generated by these pulsed emitters. The proposed technique involves the integration of the time-based pulse blanker and the wavelet-based interference mitigation technique. Aviation is the key application considered although many other applications such as transport management and navigation, environmental monitoring, and telecommunications would benefit. A performance assessment of the new technique is carried out by determining the degradation of the carrier-to-noise ratio (CNR) at the output of the correlator. The performance of the new technique is compared with the traditional time domain pulse blanking approach. The results show that the proposed technique performs better than both the time domain pulse blanker and the wavelet-based interference mitigation algorithm. Hence, the integrated pulse mitigation approach can be employed to provide an enhanced degree of interference detection and suppression.

This paper analyses flight trial results to study the overall performance and limitations of a GPS/Pseudolite/INS integration approach for aircraft precision approach and landing applications. For this purpose, the series of approaches were flown at Wedderburn Airfield, Australia. The analysed results show that pseudolite signals strengthen the ranging signal availability and the satellite geometry. Most of the geometry enhancement is found in the vertical position component, improving the accuracy of the aircraft's altitude. Furthermore, the results reveal that the inclusion of a pseudolite enhances both internal and external reliabilities. A dramatic improvement of the external reliability in the vertical component is observed.

There is currently considerable interest in the international regulations for preventing collisions at sea (the COLREGS). Suggestions for changes are made, but their validity is difficult to assess because there is little possibility of testing new proposals before they are introduced. There is, however, the possibility of considering the history of the COLREGS, and their effectiveness, as they have evolved over the years. In this paper, the author's aim is to look at the lessons that may be learned from one, particularly tragic, collision between the Princess Alice and the Bywell Castle in 1878. Opinions differ as to whether a study of history is likely to be a useful exercise.

The introduction of AIS in 2002 and the drive to introduce electronic navigation aids to merchant ships had the principal stated objective of improving safety by enhancing situational awareness. This paper reviews the various types of electronic equipment fitted to vessels during the past five years in order to assist the watch-keeper, comments on the reduction in core watch-keeping skills and argues for a back-to-basics approach for watch-keepers. A version of this paper was first presented at the RIN conference NAV 07 in October 2007.

This paper presents a new method of vessel heave compensation based on a new breed of commercially available low cost GPS receivers that can measure and record the carrier phase observable. The technique is based on the extraction of a highly accurate velocity estimate from standalone receivers using time differenced carrier phase observable. Two trials have been undertaken, one using a Spirent GPS signal simulator and another conducted at sea. The simulator trial thoroughly tested the use of commercially available low cost receivers for this method of velocity estimation through their comparison with higher grade receivers and quantified the errors under varying dynamics. The sea trial tested the heave algorithm against other heave sensors and an accurate reference provided by an Applanix POSRS and showed it to be capable of producing a heave output to rival inertial based heave sensors using commercially available low cost GPS receivers.

In this paper the author introduces a new method of collision avoidance for multi-target encounters. The method combines the qualities of a sequence of necessary manoeuvres with some optimisation elements and supports any given ship domain. First the problem of determining the optimal course alteration manoeuvre for given ship domain model and multi-target encounter situation is solved. The solution consists of analytical formulas and numerical algorithms combined to achieve low computational complexity. Then this solution is further used to construct a method of planning ship trajectories, which are safe, economic and intuitive for navigators. Example scenarios and the resulting trajectories are also provided. All of the algorithms, formulas and their derivations in the text are presented explicitly, so that they could be directly applied in any collision avoidance system.

Navigation involves the integration of methodologies and systems for estimating the time varying position and attitude of moving objects. Inertial Navigation Systems (INS) and the Global Positioning System (GPS) are among the most widely used navigation systems. The use of cost effective MEMS based inertial sensors has made GPS/INS integrated navigation systems more affordable. However MEMS sensors suffer from various errors that have to be calibrated and compensated to get acceptable navigation results. 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 potentially degrade the system performance. In this paper, the Allan variance method is used to characterize the noise in the MEMS sensors. A six-position calibration method is applied to estimate the deterministic sensor errors such as bias, scale factor, and non-orthogonality. An efficient thermal variation model is proposed and the effectiveness of the proposed calibration methods is investigated through a kinematic van test using integrated GPS and MEMS-based inertial measurement unit (IMU).

The acquisition of accurate and timely traffic information is a vital precondition to rational traffic decision making. Intelligent Transportation Systems (ITS) are bound to be the outcome when modern traffic systems develop to a high degree. In ITS, instantaneous traffic information can be collected by the Floating Car Data (FCD) method. Based on the establishment of the Shenzhen Urban Transportation Simulation System (SUTSS) in China, the authors explored how to use 4000 taxis as the data collection sensors in Shenzhen, a southern city in China which borders Hong Kong. The authors introduce the procedures and algorithms for the computation and map-matching of road segment velocities to a digital road network. To superimpose the near real-time traffic information onto a digital map, coordinate transformation is required and the transformation precision is analyzed using field testing data. Due to the nature of FCD, continuous GPS data such as routing velocities and coordinates can be collected by any GPS equipped vehicle. Therefore, relevant algorithms are developed and utilized for the map-matching according to probability and statistical theories. To evaluate the reliability of proposed map-matching method, the confidence levels are calculated statistically, from which it can be determined whether the positioning data is valid or not with predefined threshold values. Furthermore, road segment velocity matching methods based on the Metropolis criteria is extended and relevant validation is carried out through the comparison of estimated and measured results. The major objective of this method is to obtain more accurate road segment travel time through the combination of those estimated by FCD and historical ones. This can significantly improve the reliability of instantaneous traffic information before its web publication. The final part of this paper introduces the architecture and the realization of a web Geographical Information System (GIS) and FCD-based instantaneous traffic information dissemination system for the whole of Shenzhen City.

A direct method for obtaining the two possible positions derived from two sights using vector analysis instead of spherical trigonometry is presented. The geometry of the circle of equal altitude and of the two body fixes is analyzed, and the vector equation for simultaneous sights is constructed. The running fix problem is also treated.