This paper discusses the technical, administrative and certification compatibility issues associated with satellite augmentation of GPS/GLONASS. It indicates that the Signal-in-Space specifications are central to compatibility and interoperability. ICAO Standards and Recommended Practices are a key mechanism for interoperability. The paper recommends that one standard be implemented worldwide. It also urges a mechanism for the co-ordination and management of augmentation services.

In this paper, the ship manoeuvring problems particular to maritime search and rescue are investigated. A solution to such problems is necessary for successful ship handling to save human life. A fuzzy gain scheduling Proportional Derivative (PD) controller, using a back-propagation algorithm, is developed to solve these maritime search and rescue problems. The parameters of the proposed PD controller are determined on-line by fuzzy rules and adjustable fuzzy reasons. The proposed controller is self-adaptive and can accommodate the effects caused by wave or wind disturbance. Some computer simulations are provided to illustrate the use of the main ideas.

Over the last few years, on-the-fly integer ambiguity resolution for GPS has proven to be successful over short baselines (<20 km). However, the remaining challenge has been to extend the length of the baseline between the reference station and the mobile receiver, whilst still maintaining the capability of on-the-fly resolution and true carrier-based kinematic positioning. The goal has been to achieve centimetric level positioning at ranges of over 500 km. New techniques have been developed at the University of Nottingham to allow very long baseline integer ambiguity resolution, on-the-fly. A major problem with the use of carrier phase data is that posed by cycle slips. A technique for detecting and correcting cycle slips has been developed, and its use is discussed in this paper. The new technique has been proven through a series of trials, one of which included two flights to the North Pole, performing centimetric level positioning all the way to the pole. For many years, the GD Aero-Systems Course of the Air Warfare Centre based at RAF Cranwell executed a series of equipment flight trials to the North Pole, called the ARIES Flights. In May 1996, the authors were fortunate to take part in both flights, via Iceland and Greenland, to the North Pole. Based on reference stations at Thule Air Base, integer ambiguity resolution was accomplished, on-the-fly, and centimetric level navigation maintained throughout the flights. Earlier trials detailed in the paper demonstrate that the technique can resolve integer ambiguities on-the-fly within a few seconds over a baseline length of approximately 134 km, resulting in an accuracy of 12 cm. The majority of the residual error source for this being the ionosphere.

Satellite Based Augmentation Systems are being developed in Europe (EGNOS), the USA (WAAS), and in Japan (MSAS). As part of their support to EGNOS, NATS and Racal have developed and deployed a prototype SBAS system called the Northern European Satellite Test Bed (NEST Bed). NEST Bed uses GPS L1/L2 reference stations at: Aberdeen, Rotterdam, Ankara, Cadiz, Keflavik, and Bronnoysund. Data is sent to the Master Control Centre at NATS Gatwick Services Management Centre for processing. The resulting 250 bits-per-second message is sent to Goonhilly for up-linking by BT to the Navigation Payload of either the Inmarsat AOR-E or F5 spare satellite. NEST Bed was deployed and commissioned during summer 1998, and flight tests were successfully demonstrated at the September 1998 Farnborough Air Show where approaches were flown to Boscombe Down on the DERA BAC1-11 aircraft. In October 1998, a NATS/FAA flight trial was held in Iceland involving NEST Bed and the FAA NSTB. NEST Bed is also being used for SARPS validation.

The complex and far-from-intuitive issue of establishing how and when to act when manoeuvres are to be performed in space is discussed here in a simple graphical way. An analysis was made of the effects on the parameters of an orbit of low thrusts in three directions: tangential to the orbit; normal to it in the orbit plane; and normal to the orbit plane. An outcome is that, in order to obtain a desired effect, and at the same time minimize the undesired ones, it is better to use only a tangential thrust or only a normal one rather than a combination of simultaneous tangential and normal thrusts. Thus it is not necessary to investigate any alternative orientation of the thrusters. A manoeuvre can be accomplished by thrusts given either only once along the orbit path, or in more than one orbital point. Diagrams are produced which give a quick insight into the manoeuvre philosophy for both kinds of action.

This paper describes an algorithm for evaluation of magnetic compass deviation based on the least squares method. An automatic system was built, coupled with a magnetic compass recording device, for fine estimation of the deviation curve on the basis of an incomplete compass swing circulation.

This, and the following two papers, were presented during the European GNSS98 Symposium held at the Centre de Congrès Pierre Baudis, Toulouse, France, from 20–23 October 1998.

It is now clear that Global Positioning Systems (GPS) will be the primary navigational and positioning tool used as we move into the 21st century. As a result of the continued expansion and development of GPS, concerns have been voiced about the liability associated with development, construction, and use of the system. No short paper can explore all of the various liability issues associated with GPS. However, this paper will touch upon various liability issues in the hope that this analysis will continue with the development of GPS.

The objective of this paper is to illustrate a methodology for the enhancement of meteorological marine forecasts tailored to the needs of navigation. The study consists of two parts: (1) Theoretical background. Introduction to numerical models for weather forecasting used by meteorological centres. A review of the most reliable equations for prediction of intensity and direction of wind and sea state. In particular, reference is made to the tables for wind forecasting developed by R. Mayençon and A. Pezzoli and the equations for prediction of sea state obtained by K. Haselman and D. J. T. Carter in light of the JONSWAP experiment. (2) Practical application. Application of the methodology to a real-world example: a weather forecast elaborated by the Meteohydrological Laboratory at Dipartimento d'Idraulica Trasporti ed Infrastrutture Civili (DITIC) of the Polytechnic of Turin. The forecast was requested by the Consorzio Prada Challenge 2000 as a meteorological support for the training they held in the Tyrrhenian Sea for the next America's Cup series.

During the past thirty years, there has been a steady growth in the size and number of ships that use the Strait of Istanbul (Bosporus), which is one of the most difficult, crowded, and potentially dangerous waterways in the world. There have been over two hundred accidents over the past decade resulting in loss of life and serious damage to the environment. Many of the proposed export routes for forthcoming production from the Caspian sea region pass westwards through the Black Sea and the Bosporus en-route to the Mediterranean Sea and world markets. The risks and dangers associated with tanker navigation, maritime accidents and environmental catastrophe are aggravated with the increase in the density of traffic, tanker size and cargo capacity, as well as the nature of the cargo. In order to ease the problem, a Traffic Separation Scheme (TSS) was established and approved by IMO in 1994. This scheme has drastically reduced the number of collisions. However, one-way or two-way suspension of traffic in the Bosporus is inevitable for ships that cannot comply with the TSS because of their type, size or poor manoeuvring characteristics. The selection of size criteria to comply with the TSS has been a matter of discussion. This paper presents the results of a real-time simulation study investigating the manoeuvring performance of large tankers in the Bosporus. The study was conducted with a simulator capable of subjecting a given hull form to any combination of environmental conditions, i.e. wind, current and wave drift forces. The results indicate that, when realistic environmental conditions are taken into account, the size of ships that can navigate safely in compliance with the traffic separation lanes is limited.

This paper describes selective tests performed in the areas of Gdansk and Gdynia VTS Centres. The main goal of the tests was to determine the accuracy of position, speed and course estimations measured by shore-based radar VTS tracking systems by using measurements of the same parameters available on board a tracked vessel equipped with GPS and GLONASS receivers. Six DGPS/GPS/GLONASS receivers were installed on board a survey vessel, and all of them recorded the vessel's route simultaneously with two different VTS radars – one at Gdansk and one at Gdynia (20 km apart). All DGPS receivers tracked the same reference station. Presented results show that the radar information can be used by VTS operators to provide navigation assistance within certain limits, but these limits must be understood. A more detailed description of the experiment was presented during the IALA Conference in Hamburg in June 1998.

This paper discusses the impact of a new generation of mobile communications, Mobile Satellite Services (MSS), on the reception of GLONASS signals in the future. The two systems are very closely located in the frequency spectrum, and the effect of this co-location has been derived. It is shown that the performance of GLONASS in a future GNSS-1 will be heavily affected by the current emissions proposed by the Globalstar consortium.

Low frequency radio navigation systems continue to play an important role in the provision of precise navigation for vessels sailing in coastal waters, and in other zones requiring high accuracy. Modernization of the existing Loran C chains, and deployment of new ones, shows there is strong interest in these systems despite the appearance of global navigation satellite systems (GNSS) such as ‘Navstar’ and ‘Glonass’. This continuation of interest is connected to the relatively low cost of operation of the systems, the low cost of receiver-indicators and the need to provide users with very precise but reliable positioning information, which at present can only be obtained by joint use of GNSS and Loran C. To make the most of such an approach, Loran C should provide accuracy and reliability similar to GNSS.

The content of this paper was presented at the International Maritime Association of the Mediterranean, 8th International Congress on Marine Technology in Istanbul, November 1997.

The effect of different measurement points on an acquired target is theoretically investigated with respect to the ARPA plotting performance. The target is described by simple geometrical figures and the echo is simplified. The actual measurement position is generally not at the centre of the target. This may cause errors in the standard plotting results. The characteristics of these errors are discussed from a nautical viewpoint.

A curve that cuts all meridians of a rotating surface at the same angle is called a loxodrome. If the shape of the Earth is approximated by a sphere, then the loxodrome is a logarithmic spiral that cuts all meridians at the same angle and asymptotically approaches the Earth's poles but never meets them. Since maritime surface navigation defines the course as the angle between the current meridian and the longitudinal direction of the ship, it may be concluded that the loxodrome is the curve of the constant course, which means that whenever navigating on an unchanging course we are navigating according to a loxodrome.

Global Positioning Systems (GPS) are now in use in many applications, ranging from GIS to route guidance, automatic vehicle location (AVL), air, land, and marine navigation, and many other transportation and geographical based applications. In many applications, the GPS receiver is connected to some form of intelligent electronic system which receives the positional data from the GPS unit and then performs the required operation. When developing and testing GPS-based systems, one of the problems is that it is usually necessary to create GPS-compatible geographical data to simulate a GPS operation in real time. This paper provides the details of a Personal Computer (PC)-based GPS simulator system called GPSIM. The system receives user way-points and routes from Windows-based screen forms and then simulates a GPS operation in real time by generating most of the commonly used GPS sentences. The user-specified waypoints are divided into a number of small segments, each segment specifying a small distance in the direction of the original waypoint. The GPS sentence corresponding to the geographical coordinates of each segment is then sent out of the PC serial port. The system described is an invaluable testing tool for GPS-based system developers and also for people training to learn to use GPS-based products.

This paper presents a novel approach to computing minimum-time paths based on a technique originally developed for use in geophysics. The technique is based on a finite difference scheme and is quite efficient in terms of both computing effort and storage. A particular strength of the technique is that it provides optimal paths to all locations in the field, thus being useful in situations where the goal is not known at the outset of the search. Details are presented on the basic technique and extensions are derived to include the integrations of resources (such as fuel store), and to provide flexibility in the objective. Two examples are given: minimum-time planning for vehicles under the influence of drift, and planning to minimise the risk of detection for a stealthy vehicle in the presence of threats.

The normal Great Circle method of computing the shortest distance between two positions on the Earth – e.g. from an aircraft's present position (PP) to a waypoint (WP) – is not accurate enough to meet present-day requirements for aircraft Nav–Attack systems.

On the surface of an Ellipsoid (or Spheroid), the true ‘shortest distance’ is along a geodesic curve between the two points, but the computation of this curve is complex, and as shown by R. Williams at Reference, the difference between the geodesic and Great Ellipse distances between two points is negligible (<0·01 nm).

The Great Ellipse through two points on a spheroid is defined as the ellipse that passes through the two points and the centre of the spheroid; it therefore has a major axis equal to the Earth's, and a minor axis that is between the Earth's major axis (for two points on the Equator) and minor axis (for two points on the same, or diametrically opposite, longitudes). Thus the problem of deciding on which Great Ellipse the two points lie is equivalent to determining the magnitude of the minor axis β of the ellipse on which they both lie.

Anticipating that transport on the West European inland waterways will increase in volume, in ship size and in speed, experiments are being carried out to investigate whether safety of navigation – including traffic management – can be improved by the employment of GPS or DGPS, electronic navigation charts, river radar and computer technology. Although waypoint navigation and collision avoidance systems are generally accepted in the maritime world, these methods could cause problems when applied on inland waterways.

The DGPS technique can be used for navigation over baselines up to approximately 100 km. However, DGPS positioning accuracy is highly correlated and degraded with the extension of its operational range. It is, hence, improper simply to carry on using conventional DGPS for navigation over longer ranges. An approach aimed at providing sufficient accuracy with the use of a minimum network of reference stations, and the modelling of GPS errors, has been proposed and tested for regional navigation over the Taiwan area. It has been shown from the test results that medium-range DGPS based on using multi-reference stations is capable of improving the RMS coordinate differences by 35%, when compared to the use of a single reference station. The RMS values can be further improved by 14% and 6% in plan coordinates and height respectively, when the modelling of atmospheric delay is applied to the differential corrections based on the pseudorange observables collected from the multi-reference stations.

Sir Laurence Kirwan, Director and Secretary of the Royal Geographical Society from 1945 to 1975, and one of the founders of the Institute, of which he was an Honorary Member, died in London on 16 April 1999 aged 91. The events that took place early in 1946, and led to the foundation of the Institute of Navigation the following year, have been well documented by Pat Hansford in his article in the special issue of the Journal (September 1997) published to commemorate the Institute's fiftieth anniversary. Kirwan was a member of the original Steering Committee and then of the Provisional Council which undertook the preliminary work that culminated in the inaugural meeting in March 1947. He served on the first elected Council as Chairman of the Executive Committee, which in those days assumed responsibility for administering the Institute between meetings of the Council.

In his article, Hansford recalls how the Royal Society, when approached about the formation of the Institute, had suggested that (in the somewhat uncertain situation immediately after the war) the new body might thrive best, at any rate to start with, under the aegis of an existing scientific society with similar objectives. Kirwan, then the recently appointed Director of the Royal Geographical Society, took the suggestion up by proposing various ways in which the RGS might assist the new body, and notably by offering it accommodation; and the Institute has, of course, been at the Society's house ever since. The original accommodation was not lavish but, quite apart from the prestigious address and pleasant and appropriate surroundings, the facilities available included the use of the Society's lecture theatre and the Council and committee rooms. It is difficult to see how the new body, with a handful of members and no money, could have survived without some such assistance. But it was perhaps at a deeper level that the arrangement was to prove so influential, for it brought the young Institute into immediate contact with the liberal traditions of the learned societies in this country, concerned essentially with the subject rather than the benefit of its members, no doubt very much as the Royal Society would have wished.