Radio Aids Research Articles

An introduction to radio aids to air/sea rescue

The paper surveys developments in radio aids to air/sea rescue since 1940, and discusses the medium frequency c.w. and v.h.f. radar beacons in general use during the second world war, together with later post-war developments of these equipments. The development of a v.h.f. c.w. dinghy beacon and the use of the airborne v.h.f. homer as the search equipment are discussed together with the change in operational requirements for a personal equipment with communication facilities. The author suggests that a crystal-controlled v.h.f. beacon having a low duty cycle may most readily satisfy international requirements for future radio aids to air/sea rescue. The desirability for a crash location beacon is also put forward.

The TALBE: a v.h.f. c.w. radio aid for air/sea rescue

General consideration of personal beacons for air/sea rescue are discussed, and the search techniques briefly described. Suitable battery types are reviewed. The mechanical and circuit design of two c.w. beacons is described: a dinghy transmitter without speech or reception facilities, and a personal type (TALBE—Talk and Listen Beacon) giving these facilities.

Systems Analysis Approach to the Choice of a Long Distance Navaid

This paper describes and evaluates the various factors involved in selecting an all-weather, general-purpose, type of navigation system for the radio guidance of civil and military aircraft of all types at long distances from ground-based transmitters. An analysis is made of the factors which affect the range, accuracy, reliability, cost, suitability, and operational utilization of available and proposed radio navigational aids for long-range operation in the light of the most recent investigations and requirements of the Air Coordinating Committee and the International Civil Aviation Organization (ICAO). Considerations affecting the "optimum" choice of frequencies are presented based upon the most current operational information of radio wave propagation. An "optimum" frequency of 60 kc is selected, based on minimum transmitter power requirements. A brief description is given of the principles involved in several representative continuous wave and pulse types of radial, circular, and hyperbolic position-fixing aids and a comparison is made of pertinent operational and technical characteristics leading to the choice of a possible general-purpose system for civil and military applications. Consideration is given to the possible improvement in the tolerable signal-to-noise ratio, and consequent range extension, of these systems by the application of cross-correlation, coherent, or synchronous detection techniques. Based upon the above criteria, an all-weather, single-site, combined radial and circular system, designated Navarho, is selected as possessing the greatest promise of fulfilling most of the requirements for a general-purpose, ground-referenced system, yielding information automatically, instantaneously, and directly to the pilot.

Radio Aids to Air Navigation. J. H. H. Groves. Heywood, London, 1956. 138 pp. Illustrated. 21s.

Radio Aids to Air Navigation. J. H. H. Groves. Heywood, London, 1956. 138 pp. Illustrated. 21s.

The Visibility of Stars during Twilight

One of the problems in arctic navigation by astro is the twilight period. At this time, if the Moon is below the horizon, suitable objects for sextant observation are not easy to find. The difficulty is aggravated by the fact that on certain flight paths the arctic twilight may last for many hours. It must also be remembered that in these areas the behaviour of the magnetic compass and of radio aids are often unreliable and this increases the relative importance of astro-navigation. With the introduction of the periscopic sextant into air navigation it has become possible to pre-set the instrument for a given star or planet and satisfactory observations may be possible when the heavenly body is still below the level of casual perception for the unaided eye. In this connection it is necessary to know what stars are likely to be seen under twilight conditions if efficient flight-planning is to be carried out.

Radio Aids to Navigation - Radio Aids to Maritime Navigation and Hydrography. International Hydrographic Bureau, Monaco (1956), viii + 446, 223 figs, 50 full-page ills., cloth, 10·75 × 7·25 in. $8.

Radio Aids to Navigation - Radio Aids to Maritime Navigation and Hydrography. International Hydrographic Bureau, Monaco (1956), viii + 446, 223 figs, 50 full-page ills., cloth, 10·75 × 7·25 in. $8.

Some Operational Advantages of Pictorial Navigation Displays

In the preparation of an evaluation program for several pictorial navigation displays, developed under sponsorship of the Air Navigation Development Board, it was necessary to make a study of possible operational advantages of the use of such displays. When compared to conventional symbolic instrumentation for displaying navigation information, the pictorial displays appear to have three primary advantages: 1) Continuous usable navigation information is supplied to the pilot in all airspace within range of the ground radio facilities. 2) Navigation workload on the flight crew is materially reduced. 3) A reduction in number of ground radio aids should be possible if most aircraft were equipped with pictorial navigation displays. Brief description of several pictorial computers is included.

International Civil Aviation Organization

The second Air Navigation Conference sponsored by the International Civil Aviation Organization (ICAO) opened in Montreal on August 30, 1955. Technicians representing 26 countries members of ICAO, three non-member countries and five international organizations attended the Conference, which had on its agenda radio aids to final approach and landing, long-distance navigational aids, aircraft separation in high density traffic areas, visual flight rules, and minimum height rules. The Conference requested ICAO members to set up a system of reporting “near-misses” between aircraft in flight, with the purpose not of enforcing existing rules of the air by taking disciplinary action against the pilots concerned but, by a systematic analysis of near-misses and the determination of their causes, to find a way of avoiding them. The Conference noted that research was being carried on in regard to anti-collision lights, and recommended that member states forward to ICAO information on the results of their trials and experiments. The Conference also recommended that ICAO revise its international standards to prohibit all flights in controlled airspace between sunset and sunrise unless such flights were carried out under air traffic control from the ground, with specific permission from the appropriate authorities. After considering complications resulting from aircraft flying under Visual Flight Rules (not under ground control) in controlled airspace, the Conference proposed an amendment to the international standards on rules of the air which would bring under traffic control a number of such flights, and made several other recommendations designed to minimize the traffic complications resulting from flights not under ground control.

Radio aids to marine navigation. An informal lecture to the Radio Section

Radio aids to marine navigation. An informal lecture to the Radio Section

IRE Standards on Radio Aids to Navigation: Definitions of Terms, 1954

IRE Standards on Radio Aids to Navigation: Definitions of Terms, 1954

Radio aids to marine navigation

Radio aids to marine navigation

IV—Radio and Radar Aids

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Radio aids for airport control. Radio Section informal lecture, 23rd February, 1953

Radio aids for airport control. Radio Section informal lecture, 23rd February, 1953

The Use of Loran for Survey Work in the Pacific

During the course of recent hydrographic and oceanographical investigations in the Pacific, H.M.S. Challenger made considerable use of the extensive Loran coverage now provided by the United States. This marine radio position-fixing aid was particularly useful in the west Pacific in the area between Japan and New Guinea where the coverage of ground-waves is considerable. In this article an attempt is made to describe some of the work for which Loran was used, the principles on which it was used, and the accuracy expected and errors obtained. No attempt has been made to describe the operation of the system, which has been adequately covered in this Journal and in numerous other publications.

Radio aids to navigation

For centuries mariners have located their ships on the earth's waters by compass and dead reckoning and here the vagaries of the weather had to be considered. Since electronics came to the navigator's assistance, he has been able to obtain his fixes regardless of weather. Some of these electronic aids are described here.

A survey of external and suppressed aircraft aerials for use in the high-frequency band

External wire aerials, which are usually employed at frequencies below 20 Mc/s for radio aids on aircraft, are not preferred on high-speed aircraft because of their drag and general mechanical unsuitability. It becomes necessary to include the aerials within the aircraft skin, when they are usually referred to as suppressed aerials.In the paper, information on well-known external wire aerials, such as fixed inclined wires (long and short), inverted-L wires, trailing wires and shunt-wire-fed wings, is compared with that obtained with various suppressed aerials. Some of the suppressed aerials have performances which compare favourably with the external wire types and in certain respects have apparently better electrical characteristics. In particular, aerials which are folded or near-end fed, or those which involve an insulated stabilizer unit, have a wide bandwidth and are reasonably efficient. The impedance characteristics of some of the suppressed aerials are such as to make their use suitable where it is required to cover frequencies lower than the h.f. band.For h.f. suppressed aerials, where the wavelength is comparable to the aircraft dimension, the view is held that an efficient suppressed aerial will require the excitation of either the whole aircraft or a large part of it. Various methods of excitation are discussed and experimental evidence is given. Since the stabilizer is usually the only vertical component, its use is contemplated for vertical polarization; similarly, the wings and horizontal units of the aircraft are considered for horizontal polarization.Measurements of the electrical characteristics of aircraft aerials present considerable difficulties. They are not often satisfactory on a grounded aircraft, and flights are very uneconomical for preliminary experiments. In order to overcome these difficulties, the method of scaling aerials on scale-model aircraft is widely used to determine the performance of both external and suppressed aerials. Some of the suppressed types of aerial which have shown satisfactory characteristics obtained with the scale models have been installed in aircraft, and successful long-range flights using these aerials in the 2–20 Mc/s communication band have been made.

Radio Position Lines and the Intercept Method

In 1877 a two-volume book, Nouvelle Navigation Astronomique, edited by the astronomer Villarceau and a naval officer, Magnac, was published in Paris. The book, which may be considered the most comprehensive work on astronomical position lines up to date, covers completely the theoretical treatment of circles of equal altitude on Mercator projections and their practical evaluation, and considers the effects of possible mistakes and errors. In the present writer's view these factors have not yet been sufficiently appreciated. It is surprising that similarly detailed descriptions of the other position lines used for navigation have not yet been published; although, apparently, the attitude towards these questions has altered since that time. The change in methods of navigation, particularly with the introduction of radio aids, has brought a variety of other position lines to the fore, and the predominance of Mercator's projection is not as universal as it was eighty years ago. In order that these premises may be clarified, a summary of the various position lines in use today is here given.

Instrument Approach and Landing Charts

The purpose of an instrument let-down is to bring an aircraft past all hills and obstructions to a particular position at low height. If the pilot follows the correct procedure, the aircraft will obviously clear the hills and obstructions. But owing to various interruptions and distractions, difficulties of reception or the need to give partial attention to other duties, he is often unable to follow the procedure exactly; he will then want to know whether departure from the procedure requires immediate rectification, or whether he is at liberty to return gradually to the correct path. A badly working radio aid, or some other difficulty, may make it necessary to abandon a partly completed approach; he will then want to know the best way to extricate his aircraft from a possibly dangerous situation. Furthermore, the pilot often has to improvise an ‘intermediate procedure’, to connect between his arrival over the aerodrome and the beginning of the let-down. For these reasons he needs to know the positions of the hills and obstructions in relation to the let-down; and the only way to present this information to him quickly and unambiguously is by making hills and obstructions the principal features of let-down charts. The local knowledge possessed by pilots of scheduled services does not lessen the need for an effective presentation of this feature on the charts, as it is precisely when landing at unfamiliar aerodromes that the charts will be most used.

Radio aids to marine navigation: the seaman's requirements

This paper deals with the requirements of the mariner in connection with radio aids to navigation. It opens with the description of the various circumstances in which other aids may fail and an impression of the positional accuracy suited to those circumstances. This is followed by a statement of the theoretical accuracy of the various radio aids which are available and of the areas in which coverage is provided at the present time; an examination is made of one or two areas in which such aids may be used consecutively in an approach to the destination, and this is followed by an impression of the extent to which these aids are employed by British ships.This leads to a brief study of the factors which govern the appeal that the various aids have to those responsible for providing equipment in ships. This opens the way to a more detailed study, from the mariner's point of view, of the shortcomings of the various aids and the directions in which development might be undertaken towards greater reliability, better performance, extension of cover, and wider application.

The Requirements for Radio Aids at Sea

The seaman requires of radio aids to navigation that they should be effective substitutes for astronomical and terrestrial methods of fixing when these fail him, either wholly or in part. For normal peacetime voyaging there has been no firm demand for a radio system that will improve on the performance of the other methods at their best. The requirements for radio aids can therefore be related to the facilities which these other systems afford. This does not, of course, imply that circumstances do not exist in which radio aids can provide a degree of assurance that the other methods might not.