The tip of the Chukotskiy Peninsula in the Soviet Far East is 86 km from mainlandAlaska and its mountains are clearly visible from St Lawrence Island. It is a ruggedtreeless land that straddles the Arctic Circle between the Bering Sea and the ArcticOcean. In winter it is snow-covered and the sea stays frozen until May.

The transmissions from GPS and GLONASS navigation satellites include information about the state of those transmissions as perceived by the control centre. In the case of GPS, for example, this information is contained in the data stream in Subframe 1 Word 3. However, with some of the failure conditions that can arise there is a delay of the order of half an hour before this message is altered to signal that a failure exists. A situation can therefore arise when the satellite signals that all is well, whereas in fact it is not. The very high levels of integrity which civil aviation require before satellite navigation can be used with confidence therefore means that the warning messages from the satellite must be augmented by some other form of monitoring. Two alternatives exist: (1) to have a monitor at some fixed and surveyed ground location which broadcasts a warning to the navigating aircraft when there is a malfunction (ground monitoring), or (2) to arrange for the navigating receiver to perform its own internal monitoring, known as receiver autonomous integrity monitoring (RAIM). Each alternative is beneficial in its own way.

This paper and the following five papers were presented at the NAV90 Conference on Land Navigation and Information Systems. The Conference was organized by the Institute in September at the University of Warwick. Complete sets of the proceedings are available from the Director, Royal Institute of Navigation, price £60 (to RIN members).

This paper takes a global overview of technical developments in vehicular navigation. From this vantage point, the author gives his perception of some of the critical issues involved in the major shakeout and consolidation which he expects to occur during the next one or two decades, and he speculates on the outcome.

Agriculture in the U.K. has, since the late 1940s, enjoyed government subsidy and insulation from free market forces. However, the post-war philosophy of ‘every acre counts’ no longer holds true in the face of surplus production and a growing public awareness of the countryside and environmental issues. Legislation relating to water pollution, public rights of way and price support mechanisms are all contributory factors to the radical changes which agriculture is undergoing at the present time. Investigations have shown a need within agriculture for the efficient use and handling of data relating to the land, and a need for new technology to exploit the inherent spatial variability of, for example, the soil. This paper will discuss the development of an agricultural vehicle positioning instrument and future research which will address the needs which have been identified.

What are we doing it for? Datatrak designed, built and prepared for the transport market, a complete Automatic Vehicle Location and Reporting System (AVLRS) that covers 95 percent of the road system of Great Britain.

A navigation strategy for an autonomous land vehicle (ALV) based on the Defence Geographic Database is currently being developed under the auspices of. the Mobile Advanced Robotics Defence Initiative (MARDI). The database is hierarchically structured, and supports the storage of an unlimited number of attributes for each geographical feature. It also expressly identifies the interconnectivity of adjacent features, making it ideal for automatic route calculation. Tactical battlefield information is being combined with the database resulting in a composite link-node map which will be searched for optimum routes using standard algorithms. Both military and geographical criteria will be simultaneously optimized. Waypoints suitable for machine vision techniques will also be extracted and used to confirm the ALV location.

The Automobile Association, Ordnance Survey, Philips BV and Robert Bosch GmbH are collaborating in a project to create and test a prototype navigation database. The project, (PANDORA–Prototyping A Navigation Database Of Road-network Attributes) which is being managed by consultants MVA Systematica, is supported by the European Community's DRIVE initiative.

The data requirements of future vehicle navigation systems such as CARIN from Philips, Travelpilot/EVA from Bosch and the Autoguide scheme for London have been examined. Digital street networks have been extracted mainly from Ordnance Survey's large-scale digital mapping, and the necessary road and traffic attributes have been collected by the AA. These data have been integrated into a specially-designed prototype database for parts of London and Birmingham and the major interconnecting roads. Data have been abstracted from the database and supplied to Bosch and Philips using the Geographic Data Files (GDF) standard developed in the DEMETER project. This dataset is being tested in field trials using prototype vehicle navigation systems. The dataset will also be provided to the DRIVE Project ‘Task Forc European Digital Road Map’ as benchmark test task number 12.

This paper describes the project, dealing with its objectives and relationship to other European initiatives, the work undertaken, the standards utilized and developed, its results and conclusions, and the lessons learned with respect to provision of data for larger areas of Europe. A glossary of technical terms and abbreviations is also included.

The mobile radio communications industry has recently witnessed a new demand for terminal equipment which can provide both communications and position reporting capabilities on a global scale–for example, the automatic monitoring of secure cargoes during international transportation. Thus, there is much interest in the development of land mobile satellite terminal equipment in the form of a single integrated unit which can economically provide both of these facilities. In this paper the development of such a unit is considered using the Inmarsat-c satellite communications service and the Navstar Global Positioning System (GPS), with extension to GLONASS possible in a receive-only version.

For a long time it has been accepted as fact that at least certain animals, such as birds and honey bees, have an in-built sense of orientation which enables them to find their way home. Less well-known examples occur among the molluscs and amphibians.

This paper describes the basic principles of a method developed to guide aircraft accurately down to the runway in a time-of-arrival constrained environment. The method is designed to be used in a ‘zone of convergence’ context or in any similar advanced air traffic control system characterized by the integration of control phases over an extended area on the one hand and true ‘computer assistance’ to the air traffic controller on the other; that is, assistance provided at the decision-making level through the automatic generation of guidance advisories.

The method includes two closely-coupled basic components; namely, a ‘predictor’, which computes a trajectory once initial conditions and plans are known, and a ‘profile manager’, which adapts the plans to meet the time constraints and generates the guidance directives on the basis of present position, actual surveillance information, aircraft operation and route constraints.

In this paper, the methods of collision avoidance by radar which have been used in the radar simulator course at Chinese marine colleges are introduced. Then some other methods of estimating the risk of collision, safe passing distance and course alteration in radar collision avoidance are presented.

A Long-range Secondary Surveillance Radar (LSSR) has been developed and recently used as an Oceanic Route Surveillance Radar (ORSR) in Japan. The LSSR is an SSR (Secondary Surveillance Radar) only system for which the maximum coverage is 250 nautical miles (n.m.). This system utilizes monopulse azimuth estimation techniques for improving the accuracy of azimuth estimation.

In this paper some interesting properties of circular orbiting satellites' ground traces are pointed out. It will be shown how such properties are typical of some spherical and plane curves that look like flowers both in their name and shape. In addition, the choice of the best satellite constellations satisfying specific requirements is strongly facilitated by exploiting these properties.