摘要:

This paper relates to loop radio transmitters for direction-finding or navigation purposes, and particularly to a method of directional transmission which has been developed by the Air Ministry at the Instrument Design Establishment, Biggin Hill, Kent, and later at the Royal Aircraft Establishment, Farnborough, Hampshire. The chief object of the method is to eliminate direction-finding equipment and to reduce operational difficulties in the aircraft. The method is one in which a characteristic of the radiation is “timed” by means of a chronograph, the time interval between a Morse signal and the characteristic indicating the bearing. A loop aerial is employed and the electromagnetic energy radiated from the loop is a maximum in one direction and a minimum in another. The loop rotates in azimuth at a speed of 1 revolution per minute and is made to send out a continuous signal. This signal is interrupted when the line of minimum radiation is in the true North direction, and a special Morse signal is transmitted at that moment to enable an observer to start a chronograph. The observer notes the time interval between “North signal” and the instant at which he perceives minimum radiation, thus obtaining his bearing from the beacon.The paper describes the various stages in the development of the beacon and refers to certain difficulties encountered and how they were met.An appendix gives typical results obtained from tests on the ground and in aircraft during experimental trials.From the results obtained, it is considered that bearings can be determined with an accuracy at least equal to that of any other wireless system of direction-finding. The work of the authors has been more particularly in connection with the use of the rotating-loop system for the navigation of aircraft, and for ranges up to about 200 miles the results show that bearings can be determined with such accuracy as is required for the purposes of aerial navigation.The investigations as to its use on ships is a matter which the Radio Research Board have undertaken.

DOI:10.1049/jiee-1.1928.0017

出版商:IEE    

年代:1928

数据来源: IET

摘要:

The following paper describes a series of experiments carried out with a rotating-loop beacon transmitter installed for the purpose at Fort Monckton, near Gosport. After an initial calibration of the beacon, a series of tests was carried out in various cross-channel ships between England, France, and the Channel Islands. In these tests the accuracy of the wireless bearings obtained from the beacon was measured at various distances and the range of the beacon for reliable working was ascertained. The night errors, which were encountered at the longer distances, were studied in more detail at various fixed positions, chosen to show the effect of transmission over sea and land respectively. In the later part of the investigation a comparison was made both at sea and on land between the bearings observed on the rotating beacon and those obtainable with a direction-finder used in the ordinary manner. From the results obtained the relative merits of the two systems of ascertaining wireless bearings for marine navigation purposes are briefly discussed.

DOI:10.1049/jiee-1.1928.0018

出版商:IEE    

年代:1928

数据来源: IET

摘要:

In the following paper three arrangements for a rotating-beacon transmitter are discussed from the theoretical point of view. These three systems are the single coil, the double-spaced coil, and the Adcock aerial arrangement.In the case of the single-coil system it is shown that under night conditions, when wireless waves can be deflected from the upper ionized layer, the signal minimum as observed at the receiver can occur at such times during the rotation of the coil as to indicate an error in the observed bearing ranging up to 80 deg. It is shown that this error is of the same order as that observed on an ordinary direction-finder under similar conditions.The treatment of the arrangement of two co-planar spaced coils, as sometimes employed for directional reception, shows that, while the time of occurrence of the minimum giving the correct observed bearing remains unaltered during all conditions of night effect and downcoming waves, other secondary minima may be obtained under these conditions, the observed bearings on which may be in error by the same amounts as those obtainable with the single-coil transmitter. As the observer at the receiver will, in general, be unable to distinguish between the main and the secondary minima, this double-coil system would appear to possess nearly the same liability to error as the single-coil system. The possibility of the two minima occurring close together will also detract from the accuracy of observation of the main minimum, even supposing it could be distinguished from the other.The third case to be considered is that proposed by Mr. C. E. Horton, viz. the use of the Adcock aerial system as a rotating transmitter. With this arrangement it is shown that a signal minimum is produced when the plane containing the pair of vertical aerials, or their equivalent in space, is perpendicular to the direction of the receiver. This minimum remains unaltered in the presence of downcoming waves at night, and as no secondary minima occur it appears that this system will give correct bearings at all times when the signal is strong enough for observation.In searching for a type of rotating-beacon transmitter upon which the observed bearings are independent of night errors, it would appear that the Adcock arrangement is the most hopeful; and it is, therefore, proposed to consider this system in more detail from the practical standpoint.

DOI:10.1049/jiee-1.1928.0019

出版商:IEE    

年代:1928

数据来源: IET

摘要:

The paper discusses some of the troubles that may arise in the practical use of lead cable-sheaths owing to physical weaknesses, and it shows how these weaknesses are connected with the inherent grain structure in the metal and the stream-line structure due to the extrusion process. In the early part of the paper existing metallurgical knowledge is reviewed for the benefit of electrical engineers, and illustrations are given from the authors' own investigations into the crystal structure of cable sheaths. Various factors involved in the much discussed disintegration by vibration are examined, and the improvement of pure lead by the employment of alloying metals is treated both theoretically and practically. Special apparatus for the vibration tests is described, and the paper closes with a study of the “weld” and a description of a new type of cable press which produces a cable sheath that is weldless. The investigation has been carried out at intervals over the past 7 years in the Research Laboratories of Messrs. W. T. Henley's Telegraph Works Co., to whom the authors are indebted for permission to publish the results.

DOI:10.1049/jiee-1.1928.0022

出版商:IEE    

年代:1928

数据来源: IET

DOI:10.1049/jiee-1.1928.0031

出版商:IEE    

年代:1928

数据来源: IET