This paper is concerned with an investigation into the use of artificial neural networks in the design of fuzzy autopilots for controlling the yaw dynamics of a modern Royal Navy warship model. Results are presented to show the viability of such an approach and that effective designs can be produced.

Today, no single technology has more broad-reaching potential for worldwide civil aviation than the future applications of satellite technology. These applications represent the greatest opportunity to enhance aviation system capacity, efficiency and safety since the introduction of radio-based navigation systems more than 50 years ago. The foundation for this optimism is the Global Positioning System (GPS), a satellite-based radio navigation system operated and controlled by the United States Department of Defense (DoD). In December 1993, DoD declared GPS to be in initial operational capability (10c), which means 24 satellites are now in orbit, available and usable for satellite navigation. The Federal Aviation Agency (FAA) responded to this potential through initiation of a comprehensive satellite programme involving government, industry and users to expedite research, development and field implementation of satellite-based navigation services.

Map reading has always been and will continue to be a vital military skill. The ability to relate map to ground and vice versa is an essential skill for all ranks. Having determined his position and that of his objective, a soldier must be able to navigate between the two in the most expeditious manner. The advent of the Global Positioning System GPS has not diminished this requirement. Map reading and navigational skills are practical subjects that must be regularly practised and assessed if skills are to remain high.

The detection of flying targets in the night sky has provided interest for bird migration research over many years with methods largely dependent on moon watching or the use of radar and infrared camera. These methods lack the versatility of the system described in this paper which detects and automatically records aerial targets in the night sky of a size greater than 5 cm and at a distance of 100 to 1000 metres from the observer. The principle design features are first, an optical device for receiving images of targets on two high-sensitivity CCD matrices when illuminated by white light from searchlight beams and secondly, instantaneous parallactic electronic computation enabling the distance from device to target to be accurately measured, and sequential images of each target to be recorded to computer. The device has been tested on targets during the main seasonal nocturnal migration of birds and provides accurate image details of important target flight parameters including: altitude, linear size (wing span and body length), direction of flight (ground track), orientation of the body axis – heading, ground speed, wing-beat frequency, number of wing-beats in each series of beats, duration of the pause between each series of wing-beats, and type of flight trajectory. There are also the potential practical applications for aviation bird-strike at night as well as the remote monitoring of insects, bats and other targets of natural and artificial origin.

This paper was first presented at GNSS 2002 – European Navigation Conference – held in Copenhagen, 28th to 30th May, 2002.

At the 5th GNSS Symposium, held in Seville in 2001, the authors presented a paper entitled ‘The Portuguese DGPS network’, which began by addressing the current need for a DGPS service, given the removal of Selective Availability (Moore et al., 2001). In that paper, the benefits of DGPS for mariners, namely in terms of accuracy and integrity, were discussed and presented, in order to show that the option to embrace DGPS was, and is, still valid because it can provide the best accuracy and integrity at sea. However, the accuracy advantage afforded and the integrity check performed by DGPS are only useful if the DGPS service reaches very high standards of availability and continuity. It would be almost useless to have a DGPS service with low availability and continuity, because it could mean a ship losing the differential corrections in restricted waters, where the service is most needed. In summary, the level of benefit gained from DGPS is directly proportional to the user availability of the service and to its continuity. Having discussed accuracy and integrity last year, this paper covers issues related to availability and continuity (continuity replaced the previously used concept of reliability). The availability and continuity requirements recently adopted by the International Maritime Organization (IMO) and the International Association of Lighthouse Authorities (IALA) are presented, as well as the ways by which DGPS services can meet the very high requirements for the harbour entrance and approach phase of navigation. The concepts used in the Portuguese DGPS network to minimize downtime and ensure the highest reliability and availability, are presented as an example.

This article proposes a batch-mode algorithm to handle the large databases generated from experimentations using probe vehicles. This algorithm can locate raw Global Positioning System (GPS) positions on a map, but can also be used to correct map-matching errors introduced by real time map-matching algorithms. For each journey, the algorithm globally searches for the closest path to the GPS positions, and so is inspired from the “path to path” algorithm's family. It uses the Multiple Hypothesis Technique (MHT) and relies on an innovative weighting system based on the area between the GPS points and the arcs making up the path. For high performance, the algorithm uses an iterative program and the data is stored in tree form.

There has recently been some discussion in the Journal1 as to the meaning of the word ‘dyoll’ when it appears in English ship inventories of the years 1410–12, which have been partially published, by Nicolas2 and Sir Alan Moore.3 Nicolas quotes from the Accounts and Inventories of John Starlyng, Clerk of the King's Ships to Henry IV, but he mistakenly dates these documents 1338, which date has been corrected by Moore to 1410–12.

The BeiDou navigation satellite system (BDS) has been providing a regional service in the Asia–Pacific area since 27 December 2012, and a new Inclined Geosynchronous Satellite Orbit (IGSO) satellite IGSO-6 joined the 14-satellite constellation in operation on 29 March 2016. In this paper, the signal and positioning performance of IGSO-6 are assessed. Compared with other IGSOs, the carrier-to-noise-density ratios of IGSO-6 show comparable performance for the B3 signal and a lower power level for the B2 signal, while the B1 signal is more powerful and has the lowest noise and multipath errors. The satellite-induced code bias of IGSO-6 was investigated and indicates that IGSO-6 has similar characteristics to other IGSOs. The different inter-frequency bias variations among IGSOs with daily periodicity are demonstrated. The BDS positioning performances with IGSO-6 were investigated in Single Point Positioning (SPP) and Precise Point Positioning (PPP) modes at the 95% confidence level. For SPP, there was an improvement of about 4·9% and 3·6% in the horizontal and vertical components, respectively. The convergence time was improved by about 18·3% and 17·8% in the horizontal and vertical components for positioning accuracy to be better than 50 cm, respectively.

Over 10 years ago, a paper was published at the ION-GPS ‘99 conference that detailed the design of the navigation system implemented on the Global Hawk UAS program then being run under the auspices of DARPA. Since that time, many changes have occurred in the program including transition from DARPA to USAF management, the development of the larger Block 20/30 unmanned aircraft (UA) and the awarding of the Broad Area Maritime Surveillance (BAMS) program to Northrop Grumman which is based on the Global Hawk Block 20/30 aircraft. In addition, many changes have been made to the aircraft navigation system as well as many lessons learned on the kind of navigation system required to support a long endurance UA. The result has been a much more robust set of navigation sensors that allows this aircraft to successfully support the efforts to counter terrorism in the world today.1

A relatively novel approach of autonomous navigation employing platform dynamics as the primary process model raises new implementational challenges. These are related to: (i) potential numerical instabilities during longer flights; (ii) the quality of model self-calibration and its applicability to different flights; (iii) the establishment of a global estimation methodology when handling different initialisation flight phases; and (iv) the possibility of reducing computational load through model simplification. We propose a unified strategy for handling different flight phases with a combination of factorisation and a partial Schmidt–Kalman approach. We then investigate the stability of the in-air initialisation and the suitability of reusing pre-calibrated model parameters with their correlations. Without GNSS updates, we suggest setting a subset of the state vector as ‘considered’ states within the filter to remove their estimation from the remaining observations. We support all propositions with new empirical evidence: first in model-parameter self-calibration via optimal smoothing and second through applying our methods on three test flights with dissimilar durations and geometries. Our experiments demonstrate a significant improvement in autonomous navigation quality for twelve different scenarios.

Personal navigation has grown rapidly with the introduction of ubiquitous computing and the new generation of smart phones. Appropriate localisation is nowadays a central element for many applications and mobile services. However the proper estimation of the user's location remains a challenge. This paper presents an innovative concept for accurate and reliable positioning in challenging applications. It consists of three components: an absolute geographical reference, the hybridisation of complementary technologies and specific motion models. Two different applications illustrate this concept: urban displacement of blind people and guidance of firefighters. The validity of the concept is assessed with indoor experimental results. Finally the conclusion gives a prospective view of robust personal navigation.

Collision avoidance (COLAV) is a prerequisite for the navigation safety of unmanned surface vehicles (USVs). Since USVs have to avoid obstacles clearly and timely, i.e. the COLAV should be agile, the COLAV algorithm should have low computation complexity and make efficient COLAV decisions. However, balancing between the computation complexity and the COLAV decision optimality is still intractable at present. This paper innovatively proposes a COLAV algorithm for USVs by combining the velocity obstacle method with the predictive model method, named the collision shielded model predictive control (CS-MPC) algorithm, such that the agility of USVs COLAV is improved. The runtime of the proposed COLAV algorithm is shortened by shielding the dangerous parts of the search space of the COLAV decisions, and the COLAV decision is efficient with the aid of the accurately predicted motion trajectory by the motion mathematical model of USVs. As such, the USV can safely navigate in complex water areas where multiple vessels and obstacles exist. A series of simulations on a yacht in different kinds of encounter situations were carried out to verify the effectiveness and the agility of the proposed CS-MPC COLAV algorithm.

This paper proposes a novel autonomous navigation method for Mars-orbiting probes. Satellite-to-satellite tracking (SST) between two probes is generally deemed to involve autonomous measurements with no dependence on any external observation sites on the Earth. For the conventional two-body dynamic model, it is well known that the orbit states cannot be estimated by merely using such SST measurements. Considering the effects of third-body gravitation perturbation and the weak Mars tesseral harmonics perturbation, autonomous navigation with SST measurements alone becomes weakly observable and may be achieved by some nonlinear filtering techniques. Two significant improvements are made to mitigate the nonlinearity brought by the dynamic models. First, singularity-avoiding orbit elements are selected to represent the dynamic models in order to reduce the intensity of the nonlinearity which cannot be overcome by the traditional position–velocity state expression. Second, the unscented Kalman filter method is effectively utilised to avoid the linearised errors calculated by its extended Kalman filter counterpart which may exceed the tesseral harmonics perturbation. A constellation, consisting of one low-orbit probe and one high-orbit probe, is designed to realise the autonomous orbit determination of both participating Mars probes. A reliable navigation solution is successfully obtained by Monte Carlo simulation runs. It shows that the errors of the semimajor axes of the two Mars probes are less than 10 m and the position errors are less than 1 km.

This paper presents a method that allows mobile devices to be globally self-localised in indoor localisation systems by transmitting to them data from position reference anchors. The objective is to establish a reliable one-way down-link communication through signals used in the localisation process in a typically strong fading and multipath channel environment. This is accomplished by using signal processing techniques, including coding and forward error correction, to transmit data using a specific transmission control protocol. Experimental results, using audio as the signal between anchors and the mobile device, demonstrate successful data transmission in realistic scenarios like a common noisy and reverberant room. Spread spectrum noise-like masked signals 4·9 dB below background noise were sufficient to attain correct data reception at four metres distance between a loudspeaker anchor and a mobile device's microphone.

This paper discusses the quantification of the current risk of mid-air collision to commercial air transport aircraft receiving a Radar Advisory Service in UK Class F/G airspace. The aim is to produce the best estimate, given published data, and then to indicate what extra studies and data would be needed to improve the estimate. A study of typical flight routeings by certain aircraft types, e.g. Sikorsky S76, Saab SF340, Short SD3-60 and Aeritalia ATR42-300, could provide useful additional information. The fitment and use of ACAS could be crucial in delivering the required protection against collision.

Radar operating in the dekametric or high frequency band permits the measurement of sea-surface parameters at very much longer ranges than is possible with other techniques: 0–200 km is practical using a coast-located radar and oversea propagation, while 1000–3000 km is achievable using ionospheric reflection from a radar which may be located inland. The paper, which was presented at Oceanology International 1982 at Brighton, discusses the extraction and mapping of wave height, wave period, non-directional spectrum and surface wind parameters from Doppler radar echoes. The techniques are illustrated by the results of the UK ground-wave and sky-wave measurements and computer simulation.

The purpose of this paper is to present data and draw conclusions on the chances of collision in different areas of the waters around the UK. The subject of risk analysis has recently grown in importance, and it is often necessary for an operator to demonstrate that a proposed operation is acceptably safe before he will be given permission to begin. Risk estimates are generally of two basic types, backward and forward. Backward estimates are based upon the number of accidents that have occurred in a particular situation, and if there have been many there will be a fair degree of confidence that the risk has been accurately estimated. Forward estimates have to be made where there are so few actual accidents that no backward estimates are possible: they are based upon an analysis of the situation into a sequence of events, the probability of each being known by comparison with data obtained from other situations. Although these data may themselves be reliable, the final risk estimates will depend upon the comparability of the situations and also upon whether the sequence of events has been correctly identified.

A decade ago the opinion was expressed in that authoritative work The Use of Radar at Sea that:

In its peaceful application marine radar is hardly out of its adolescence. In twenty years it may have grown out of recognition. Whether it does so or not depends upon a number of factors of which, perhaps, the most important is progressive thought on the part of the user and his employers (p. 258).

This paper presents the preliminary study of a stratospheric segment within a satellite navigation system of present and future generation (GPS and Galileo) implemented by means of High Altitude and Very long Endurance (HAVE) platforms. The paper discusses a possible scenario in which the main features of the HAVE platform are exploited to define an innovative Aerial-Based Augmentation System (ABAS) for the provision of differential services. This particular local segment improves the provision of a differential navigation service. It is suited to the broadcasting of differential corrections in critical areas such as mountainous and sea regions where, to guarantee wide coverage, a large number of terrestrial reference stations would otherwise be required. The study includes a description of the proposed DGPS augmentation system, and a discussion of the system architecture and expected performance.