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The dynamic radio spectrum of the class 3B solar flare of 1972, August 7, 15:00 UT, over the band 10 to 2000 MHz is examined. Type II and type IV bursts in the spectrum are interpreted in terms of a piston-driven shock, which appeared to be traveling at a velocity of about 1500 km per sec and which generated pulsations in the band 100 to 200 MHz as it passed through the corona. The progress of the shock through the interplanetary plasma was subsequently monitored by Malitson et al. with radio equipment covering the band 0.03 to 2.6 MHz on the IMP-6 satellite.

The Transit navigational satellite system is expected to be in operational use during the second half of 1962, though not perhaps with its full quota of four satellites. The system, which will be of considerable significance to both air and surface navigation, is here described by its originators, Dr. Kershner and Dr. Newton, of Johns Hopkins University in the United States. Using a single of the two frequencies transmitted by the satellite, the mean navigation error will be about one mile, limited by refraction. Using both frequencies the mean error will be about ½ mile, limited by the accuracy of the satellite coordinates that will be transmitted. With elaborate equipment, it will be possible to navigate to about 0·1 mile, although the satellite coordinates that will be available to the ordinary user will not reflect this full accuracy. When all four satellites are in orbit, a fix will be available every 110 minutes, on the average, with occasional intervals of 220 minutes between fixes.

A communication system is described which enables three music circuits and an engineer's circuit to be combined. The combination is effected by using pulse time modulation in four time-division multiplexed channels. The purpose of the system is to enable a microwave link, intended for the transmission of television signals, to carry audio signals of broadcast-programme quality as an alternative. The radio equipment, primarily intended for television transmission, need not be specially designed for this particular service.Measurements of the performance of the equipment indicated very satisfactory signal/noise and signal/crosstalk ratios. When the terminals were directly connected the figures obtained were better than those recommended by C.C.I.F. When the terminals were operated in conjunction with a 25-mile radio link there was a 20dB margin in the signal/noise ratio over the recommended value. This margin was allowed for fading of the radio signal.The choice of time division as a multiplexing method is discussed, and the selection of the pulse repetition frequency, duration and time deviation is explained.A detailed description of the multiplexing circuit is given, and both the performance specification and actual measured performance figures are tabulated. Finally, the signal/noise ratio obtained with the radio link working over a 25-mile path is discussed, and the improvement which results from the use of pulse time modulation is explained.

The paper records the development of the generation of d.c. power in aircraft by windmill- and engine-driven generators, from its inception to the present day. The developments prior to the last decade are covered only very briefly. Features of generator design which have called for special consideration, or have been the subject of failure, are discussed. Sections are devoted to the choice of speed range, brush wear at high altitude, systems of ventilation, design of end-frames, and bearing failure. Some mention is made of generators designed for power supply to radio equipment, as distinct from general power services. These generators, which include high-voltage d.c. machines and high-frequency a.c. machines, have been combined with low-voltage d.c. machines, both in tandem and with a common magnet system. The latter part of the paper deals with voltage regulation, which is inseparable from the preceding part, in so far as generator design is influenced by the system adopted; self-regulating generators of various types have been used from time to time in the past. The scope does not permit more than brief mention of the design of the several types of regulator which have been used, including Tirrill and carbon-pile types. The paper shows how the control of the system voltage has been conditioned by the inclusion of an accumulator, and how it has not been possible to devise a system which gives the constant line voltage required for current-using devices, and, at the same time, permits of adequate control of accumulator charging current. Systems of paralleling, and their effect on line voltage, are also described. The electrical equipment of lighter-than-air craft is not included in this paper.

At the echo rates practicable for a routine survey of meteor activity using a narrow-beam radio equipment, it is shown that the chief limitation to the recognition of weak shower activity is the fluctuations in the rate of detection of background (sporadic) meteors. Examination of echo rates obtained with the Adelaide 67 Mc/s equipment for December 1956 and January 1957 confirms that over short intervals of time the background fluctuations are random. A significance test, intended for use as a search method for weak shower activity and non-random fluctuations in the background activity, is then developed. This test, based on echo rates, is applied to the data for December 1956 and January 1957.

INSTALLATION of the present interisland' radio network1,2 of the Hawaiian Telephone Company required consideration of many equipment and transmission engineering problems. Because of the unique geographical configuration of the area served, a great deal of preliminary investigation was needed to select operating frequencies which were both available and suitable for use from a transmission standpoint. Various types of radio equipment were then considered to determine which could best provide the needed facilities. Selection of sites and installation of radio equipment also posed a number of specific problems. With the exception of 900-megacycle (mc) links terminated at the exchange buildings in Honolulu and Wailuku, all of the radio terminals are remote from the connected exchanges; the multiplexed channels are extended over cable at Honolulu, Kauai, and Lanai, and over open-wire lines on the islands of Hawaii and Molokai.

The paper discusses the problems involved in developing a piece of radio equipment, intended for service use, from the circuit designer's laboratory model to a reliable, ?Engineered? version suitable for production. Although the principles involved are applicable to a veriety of equipments, it was thought advisable to make the paper specific, and for this reason a radio Altimeter designed by the research staff of the Telecommunications Research Establishment has been taken as a particular example.

Any form of transport calls for a communication and signalling system, and by its nature civil air transport has to rely on radio-telegraphy and radio-telephony for the majority of the services it requires, and is peculiarly dependent on navigational help by radio. As a result an extensive communication system has been built up to provide these services throughout the world, a system which is closely interconnected internationally and which provides a service for the aircraft of any country operating on the various routes. It is proposed to give in this paper a description of the system in this country and its immediate connections to the Continental and Empire networks, with some reference to the American system as an indication of the general differences between American and European practice. The paper is divided into the following Sections:? (1) The growth of the communication system. (2) Technical considerations and requirements of groundstation equipment. (3) Aircraft radio equipment and installation. (4) The Atlantic and Empire routes to the East. (5) A brief outline of the communication system in the U.S.A. (6) Future developments.

The paper describes an automatic test apparatus designed to check, under mass-production conditions and within broad limits of impedance, the multiple circuit paths found in modern radio equipment. While primarily intended as a check of wiring, the instrument operates by comparing with a standard the circuit impedances from point to point, and supersedes the common ohmmeter by working successively on alternating and direct current to provide a degree of discrimination between the reactive and resistive elements of a complex network. The comparison method used in the design provides the necessary flexibility for adaptation to differing production requirements, and it has been found that the apparatus gives a consistently greater degree of reliability in circuit checking than has been attained by purely manual operation.

Recent designs of aircraft-radio equipment have provided for operation from existing aircraft electric systems, and little attention has been given to providing the electric system that is best suited for radio equipment use. This has been a natural and proper approach, because of the relatively small load requirements of aircraft radio. Accordingly, comparatively little attention has been given to the effects of the type of power supply on the characteristics of aircraft radio equipment. It is the authors' belief that a review of the subject is desirable at this time to assist aircraft designers in making a proper choice of the electric system to be provided on future aircraft designs, as well as possible modifications to the electric systems on aircraft now in use. This paper considers the effects of the various types of aircraft electric systems on the characteristics of the radio equipment, from the standpoints of weight, efficiency, reliability, simplicity, flexibility, and emergency operation. The various types of a-c and d-c power supplies are discussed, and consideration is given to the effects of frequency and number of phases on a-c power supplies.

This paper discusses a possible method for detecting nuclear bursts in space. The method is based on the effects that the bursts should have on the phase and amplitude of high-frequency radio transmission between separated terminals on the earth's surface. Relations are derived that show how these effects should vary with time after the nuclear detonation and how they are related to bomb temperature, yield, and distance from the earth. The phase shift is independent of bomb temperature over a wide range of temperatures, whereas attenuation decreases by a factor of about 10 (in decibels) for each 50 per cent decrease in bomb temperature. Thus, absorption-measuring techniques become decreasingly attractive for detecting cooler bombs. It is concluded that measurements of high-frequency phase and amplitude change, in conjunction with very-low-frequency phase measurements, may provide a very sensitive means for detecting nuclear bursts in space by ground-based radio equipment, even for quite cool bombs. The possibility of determining bomb temperature is also shown.

In this paper a communication system is described which uses pulse-time modulation. It provides 24 channels of the quality recommended by the C.C.I.F. for the transmission of speech over international trunk circuits. The pulse-multiplex terminals operate in conjunction with radio equipment operating in the 2000 Mc/s band; this is not described here. The multiplexing equipment and its mode of operation are described in some detail?in particular the distributor and modulator. Performance figures are given.

The paper traces the history of the radio component industry's work in the specification, development, production and standardization of radio components for the Services and civil requirements from 1934 to 1947, with particular emphasis on the part played by organized industry through its technical committees, both on their own initiative and in collaboration with the Services and Supply Ministries.Detailed accounts of the development of a few individual components are given in supporting papers. Components and accessories not covered by supporting papers are referred to briefly in this paper, and some of them are used as examples to illustrate general developments or trends.An attempt is made to estimate the post-war value of war-time experience in the development and production of components, and to forecast future trends for both Service and civilian uses.

SUMMARY An account of the use of radio telephone in fire control in the Australian Capital Territory is given, and a description of the radio equipment is set out, including figures of performance. A number of features of practical value, which are desirable in the units, together with their disposition and handling, is described. While the present system has been satisfactory there is scope for immediate future development, which is outlined, and some of the limitations and disadvantages are also indicated.

The requirements for combat communication equipment, some of the problems in its development and production, and the testing and observation of it in actual operation in the field are recounted in this article. Wire, switchboards, radio equipment, types of control, and carrier systems are discussed.

The transport aircraft is inherently provided nearly complete thunderstorm-discharge protection by the metal fuselage, which forms a safe path for discharge currents that the aircraft may intercept. External elements such as movable surfaces and antennas can be protected. Airline experiences have shown that antennas frequently intercept discharges; a current surge conducted along the antenna lead-in frequently damages radio equipment and, in some cases, has resulted in fires. An effective antenna-protection unit was consequently developed, which besides protecting the ratio equipment, also records the bypassed current and charge magnitudes. Analysis of the sphere-gap pitting indicates the total-charge transfer, and small magnetic links indicate the peak currents by their magnetization. Because of the research importance of the data, these experimental units have been made available to airlines interested in cooperating with the Lightning and Transients Research Institute's program of protection researches. The discharge-current records and supplementary information from questionnaires are providing data for improved protection, and also help resolve statistically such questions as discharge-probability variations to be expected with various operating factors of geographical location, altitude, temperature, and size and speed of the aircraft.

The apparatus to be described has been developed to provide a transmitting and receiving equipment for small and medium commercial and private aircraft which will be extremely simple to operate and as foolproof as possible. Many features are introduced which, although they have been in use for broadcast and other commercial radio apparatus, have not been applied to aircraft radio equipments. For example, an electrical remote tuning system is used for the receiver, and automatic volume control on both telephony and telegraphy is provided. The equipment provides a telephonic range of 180-200 miles, and a telegraphic range of 350-400 miles, and weighs only sixty pounds complete.

This paper describes a single-sideband multiplexing system which has brought multiple-channel radio telephony into a new economic range for toll-circuit use. Problems of interchannel modulation and noise have been solved with simple, economical carrier and radio equipment. While this paper is concerned primarily with the multiplexing method, sufficient specifications on the radio transmitter and receiver are included to permit comprehension of the system as an integrated whole.

Silicon controlled rectifiers and time-ratio regulation techniques have been combined in a new power supply to provide increased reliability in railroad-radio service. Because of unusual environmental conditions, railroad locomotive and caboose radio equipment has been plagued with a high failure rate. These conditions include a wide variation in supply voltages, transient voltage surges, vibration, shock and temperature extremes. This paper describes two-way radio equipment that has been designed specifically for greater reliability in service on locomotives and cabooses. In the power supply, silicon controlled rectifiers are used in a new full-wave circuit in which both the pulse width and repetition rate of the stepped waveform are changed in order to maintain constant output voltages. Choke input filters are used to smooth the rectified secondary voltages and produce tine-averaged values of the pulses. Design considerations and performance data are discussed. This design demonstrates the advantages of applying time-ratio regulation and controlled rectifier inverter techniques to railroad vehicular-communication power supplies. These techniques can be extended to D.C. to D.C. power supplies for other applications.

The general requirements for aircraft radio equipment for air mail and transport use are discussed. This is followed by a discussion of the factors which were considered in the design of an aircraft radio telephone and telegraph equipment. A description is then given of the mechanical and electrical features of a specific equipment.

A description is given of the continuous wave telegraph, telephone, and main and emergency spark transmitters, and of the receivers and radio goniometer of the steam yacht "Elettra."

This paper describes the establishment of the radio facilities on the civil airways of the United States and their importance for air navigation. The legislation which created the Aeronautics Branch of the Department of Commerce and its organization is discussed. Description is given of the radiotelephone and radiotelegraph equipment used in the collection and broadcasting of weather information to aircraft. The transmitter used is rated at 2-kw output and is of the master-oscillator controlled type. A directive radio transmitting system using crossed coil antennas is employed to guide aircraft over the established airways. It is of such a type that the pilot receives one signal while within a narrow zone on the course, and other signals if off the course. This greatly facilitates flying under conditions of poor visibility. The regulations that have been proposed for the installation of radio equipment on aircraft are briefly given together with the more important frequencies allocated for aircraft work. The purpose and needs for these radio facilities and the way in which they have developed are also discussed.

The recent use of insulated aircraft wing or fin cap sections for radio antennas has required that consideration be given not only to the protection of radio equipment but to the protection of the insulated aircraft sections as well. Failure of simple spark gap protection used in early installations for aircraft radio equipment has been correlated to the occurrence of long duration lightning strokes, which, because of low current rates of rise, do not build up sufficient voltages across lead or tuning inductances to flash simple protective gaps. In order to provide protection against all types of lightning discharges, an aircraft lightning arrester utilizing a combination gap and series capacitor was proposed by LTRI, and has been developed in a number of commercially available types for various type installations discussed in the paper.

This paper briefly outlines the Australian system of maintenance for airborne radio equipment, and gives in more detail the results of a recent investigation into the reasons for, and incidence of, unscheduled removals of units. The probability of unscheduled removal, derived from the investigation data, was used as a criterion for the assessment of the optimum period between scheduled overhauls. It was found that, in many instances, the probability of failure is greatest immediately after overhaul and decreases with time. Comparisons of the performance of various types of units are given.

Radio equipment constructed by prewar methods and used in areas north of Australia, where the temperature is 75 to 90 degrees Fahrenheit and the average humidity is 90 per cent, does not operate satisfactorily. Mould grows on some parts, while the insulation resistance of others is lowered to unusable values. Fungicides may be used to combat mould growth, but a variety of methods must be adopted to eliminate the effect of humidity on insulation. Methods of test for mould and humidity are dealt with.

Since this paper deals with the more generalized aspects of a rather large subject, a brief resume of the background of work against which it is drawn may be of interest. Soon after world War I a certain far-sighted forester by the name of D. L. Beatty envisioned the tremandous value of radio in forest fire detection and suppression.

Important considerations in the design of a microwave system are power output from the transmitter, the antenna size, the distance from a terminal to the repeater, the path obstruction clearance, and the value of noise that will be permissible. The heart of this entire system lies in the method of interconnecting the radio equipment at the repeater site. The interconnection described in this paper was accomplished by back-to-back hybrid transformers rather than costly drop insert equipment.

A series of tests in microwave propagation over a sea path of length 1.14 times the optical horizon was conducted off the coast of Natal during the winter months, April–August, 1953. The purpose of the investigation was to study the effect upon signal strength of variations in the structure of the refractive-index profile of the atmosphere in the first few hundred feet above sea level. The radio equipment operated at a wavelength of 10cm, and vertical polarization was used throughout the tests.

The paper deals with a new conception of designing electrical apparatus such as that employed in communication, embracing telegraphy, telephony, television and light-current electrical applications generally and provides an improved and more economical method of circuit manufacture.In order to give electronic apparatus, a form which lends itself to fully mechanized production methods, a principle has been evolved of treating a circuit, not as an assembly of component elements but as a “compound” whole. Deposited conducting materials and a preformed dielectric plate replace the chassis and the multitude of parts in their more familiar form.Unlike earlier methods, in which connecting paths between prefabricated components were formed by deposition, in the method described the plate is given a predetermined structural form which determines the electrical characteristics of the completed circuit. The insulated plate, apart from acting as the support, also serves as the coil former and the dielectric of fixed capacitors.The design conception is such that electronic circuits can be produced in final form by a fully automatic electronically controlled processing machine which is described as “E.C.M.E.”—the Electronic Circuit-Making Equipment. (Section 5.)

VHF air-ground-air teletype communications by ionospheric scatter propagation have been shown to be feasible. Field strength measurements and baud error data were obtained over a 1500 statute mile flight path across the auroral zone. No degradation of system performance during periods of intense magnetic disturbances was observed; most auroral displays were accompanied by signal enhancement. System performance was evaluated using three orders of frequency diversity and up to six orders of space diversity. Successful teletype operation requires at least two orders of diversity to overcome the severe rapid fading inherent in ionospheric scatter propagation. Synchronous reception was used for the experiment and is recommended for operational systems. An air-ground-air system employing antennas, transmitters and receiving techniques currently available is shown to provide an extremely reliable teletype channel to distances of the order of 1200 statute miles.

The recently developed HC-278 digital data modem provides full-duplex data transmission at rates up to 1200 bit/s over voice bandwidth channels in fixed or transportable ground electronic systems. Using phase continuous frequency shift modulation, the modem meets the operational requirements of JCS Publ. 10 (TADIL-B) and the interface requirements of MIL-STD188B. Suitable transmission channels include wire lines and tropospheric scatter radio equipment. Maximum usage of digital techniques and integrated circuits provides economy, reliability, simplicity, and compactness. The modulator accepts synchronous serial digital data at standard rates of 75, 150, 300, 600, or 1200 bit/s and converts the bits into tones representing MARK frequency (logical 1) and SPACE frequency (logical 0). At the receiving terminal, the composite line signal containing the above tones is decoded into the original serial bit stream. System timing is derived from a crystal oscillator with a frequency of 1.0752 MHz and stability of 1 \times 10^{-7} per month.

Before 1980, satellites will probably be a wellestablished means for point-to-point communication on earth. A wide variety of passive and active satellite systems are being studied, and some studies are supplemented by experimental programs. The active systems seem more promising because of their larger capacity for a given weight in orbit with a given investment in ground terminals. Of the active systems, that which offers the greatest capacity is the geocentric stabilized station-keeping satellite in a synchronous equatorial orbit. This satellite is in direct line of sight of almost half of the earth's surface. The orbit is unique in that the satellite may have little motion about the line of sight; this may permit the use of large stationary ground antennas, in addition to the directive antennas on the satellite which cover the visible earth. This report concerns the satellite design and payload weight required to provide a given channel capacity. It is oriented toward commercial point-to-point communication, where costs dictate conservative techniques. (Author)

This paper is a brief guide which should assist in the examination of radio and similar equipment to decide whether or not it is suitable for tropical use.

THE importance of the use of radio in aerial navigation is well known. Of comparable importance to the operation of the aircraft, however, is the use of electricity in other forms, as for instance for engine ignition, for lighting, for control, and a variety of purposes. Since commutators and other forms of arcing contacts used in this equipment may cause interference with radio under some conditions, careful planning is necessary to get the fullest use from both power and radio equipment, and not over-burden the aircraft with attachments solely to make the radio work.