摘要:

Aircraft aerials must satisfy severe environmental and aerodynamic conditions, besides meeting particular electrical requirements. These conditions are discussed in the paper, and solutions shown to some of the problems. In particular, aerials for h.f. and v.h.f. communication and v.h.f. navigation systems are described. Problems associated with aerial systems for automatic landing equipments are discussed, and a number of solutions are proposed. At this stage, virtually the beginning of multiple systems, it is improbable that the solutions proposed will be final.The basic problems of v.h.f. aerial siting have not been discussed fully, but references are given to other papers on this aspect of the subject. No attempt has been made to describe aerials for l.f. navigation aids, or centimetric aerial systems whose requirements can generally be considered apart from the aircraft.

DOI:10.1049/pi-b-2.1962.0229

出版商:IEE    

年代:1962

数据来源: IET

摘要:

The design, building and testing of an improved ground radome are described. The improvement in operation has been achieved by abandoning the usual arrangement of panels and bolts and adopting instead a homogeneous shell design. The new 26½ ft-diameter radome consists of low-density foam panels which are bonded by more foam of the same density, thereby resulting in a homogeneous structure.Tests at frequencies of 6 and 9 Gc/s show an average reduction of 2% in field strength (0.2 dB) for one-way transmission. Boresight errors of ±0.9 mrad have been measured on a large aerial operating at 6 Gc/s.

DOI:10.1049/pi-b-2.1962.0233

出版商:IEE    

年代:1962

数据来源: IET

摘要:

The standard method of aligning instrument landing systems is a visual one using a theodolite to observe an aircraft flying on the localizer and glide-path beams. This method is not altogether satisfactory because it is too much dependent upon good weather and results in a great deal of flying.An improved method has been developed which is based upon aerial photography. Since photographs are taken at about 1000ft above ground level, the weather requirement is reduced to conditions in which the cloud base exceeds this figure. Moreover, the flying time is only about one-fifth of that required by the visual method.The errors inherent in the photographic method of glide-path alignment are numerically the same as those for the visual method, but for localizer alignment an error-reducing process can be applied which reduces the region of uncertainty to about half that of the visual method.Special ground equipment has been developed for measuring essential parameters of the beams before flying begins. This reduces the probability that the equipment will fail to meet its alignment specification during a flight check.

DOI:10.1049/pi-b-2.1962.0234

出版商:IEE    

年代:1962

数据来源: IET

DOI:10.1049/pi-b-2.1962.0236

出版商:IEE    

年代:1962

数据来源: IET

摘要:

Subscriber trunk dialling requires routing to be divorced from numbering. The paper discusses the various signalling problems which arise with register-translators. Basic principles are analysed rather than details of design, and a signalling philosophy is formulated as a basis of design for national and international networks. A main problem is the choice between the same or separate line equipment for the supervisory and number signalling; the paper details the merit of supervisory signalling by per-line equipment and number signalling by common-register equipment. End-to-end and link-by-link signalling, the signalling facilities to be given and the number signalling code all influence the signalling technique, and are analysed. Conclusions are given on the merits of link-by-link line signalling for flexibility of application, of end-to-end register number signalling for fast call set-up time and short post-dialling delays, and of fast coded self-checking multi-frequency signals for number transmission.The transmission features of line networks will have considerable influence on signalling-system design, particularly with end-to-end signalling for number transmission. Satisfactory design solutions are possible with limited end-to-end signalling.Speech-interpolation equipment (t.a.s.i.) applied to intercontinental circuits modifies the conclusions reached for the non-t.a.s.i. condition if account is to be taken of minimum degradation of the t.a.s.i. advantage, and the basic problem is the relative assessment of call set-up time and t.a.s.i.-advantage considerations.

DOI:10.1049/pi-b-2.1962.0238

出版商:IEE    

年代:1962

数据来源: IET

摘要:

A digitally-controlled logarithmically-varying current source is described which is suitable for incorporation in a p.c.m. feedback encoder and decoder working at 1.6 megabits/sec and transmitting telephone-quality speech.

DOI:10.1049/pi-b-2.1962.0242

出版商:IEE    

年代:1962

数据来源: IET

摘要:

A reference distortion device has been developed, initially for use in the subjective assessment of pulse-code-modulated telephony links. Noise is amplitude-modulated by the speech signal, and then added to the signal in variable proportion, to produce controllable distortion comparable with the effect of quantizing noise.

DOI:10.1049/pi-b-2.1962.0243

出版商:IEE    

年代:1962

数据来源: IET

摘要:

A resistance-network analogue technique is described for the solution of problems of space-charge-limited flow of electric current in dielectric media.Possible electrode arrangements are proposed for the construction of dielectric triodes, based on the use of a plane parallel-sided crystal of dielectric material (e.g. cadmium sulphide). The investigation of the properties of these geometries, by the above analogue technique, is described. Results are given for the valve characteristics and parameters.It is shown that a device with properties similar to those of some thermionic triodes is possible with this simple type of geometry, provided that sufficient control can be exercised over the deposition of the electrodes.

DOI:10.1049/pi-b-2.1962.0246

出版商:IEE    

年代:1962

数据来源: IET

摘要:

The instantaneous junction temperature of a transistor used as a class B amplifier is considered from very low frequencies, when the temperature is shown to follow a law similar to that of the instantaneous dissipation at the junction, to high frequencies, when the junction temperature attains a mean value which is constant throughout the cycle.An expression is derived for the instantaneous junction temperature of such a transistor, computed results illustrating the conditions of maximum dissipation in the transistor, and of maximum drive.It is shown that under conditions of maximum dissipation the peak temperature attained by the junction above that of its mount is, at low frequencies, 2.48 times that at high frequencies, while under conditions of maximum drive the ratio reaches 2.97 for a practical transistor; this higher value is due to the lower mean dissipation under these conditions.The instantaneous junction temperature of a transistor type OC22 is measured when operated under conditions of maximum drive, close agreement being obtained with the predicted results.

DOI:10.1049/pi-b-2.1962.0247

出版商:IEE    

年代:1962

数据来源: IET

摘要:

Waveguide filters using capacitive obstacles appear essentially more suitable than those using inductive obstacles for applications involving tuning over a wide frequency range.Q-factors of waveguide filters with inductive and capacitive obstacles and a central tuning screw have been derived showing the comparison between the two types of filter when tuned over 500 Mc/s in the X-band. The paper describes two possible solutions leading to multi-cavity filters tunable over several hundred megacycles per second in the 8.5–9.5 Gc/s range, and adjustable to give a wide range of bandwidths and performances.

DOI:10.1049/pi-b-2.1962.0250

出版商:IEE    

年代:1962

数据来源: IET