摘要:

The spectacular development of cellular technology in the UK is briefly reviewed and some of the less obvious developments required to cope with market demand and a multiswitch network are described. These have resulted in the UK having two of the largest mobile networks in the world today, using some advanced techniques which will be applied more universally in the pan-European digital cellular system planned to open in 1991.

DOI:10.1049/ecej:19910028

出版商:IEE    

年代:1991

数据来源: IET

摘要:

A short introduction to the background and theory of synthetic aperture radar (SAR) imaging is given. Some of the key issues in SAR design are discussed and possible future developments involving SAR operation with phased arrays are suggested.

DOI:10.1049/ecej:19910029

出版商:IEE    

年代:1991

数据来源: IET

摘要:

Technology has advanced to the point where commercial exploitation of the millimetric waveband will shortly be a reality. Defining the millimetric band as spanning from 30 GHz up to 300 GHz it can be seen that there will be ten times the spectrum that has been available until recently to satisfy all the telecommunications requirements. The millimetric frequency region is characterised by a series of atmospheric absorption bands interspersed with ‘windows’ of much lower attenuation. In the windows, although the working range of links will still be limited by the periodic attenuation due to rain, fog etc., frequency planning techniques will change little from current practice. In the absorption bands, however, the working range is quite short but it will be possible to reuse frequencies every few kilometres, opening up exciting possibilities for cordless communications and interactive wideband distribution services. The paper examines various aspects of millimetric wave propagation and exploitation.

DOI:10.1049/ecej:19910030

出版商:IEE    

年代:1991

数据来源: IET

摘要:

This is the second part of a two-part paper describing the use of digital techniques in professional sound recording. In this part the way in which digital technology can be effective in everyday usage in the studio is examined, with emphasis on editing, mixing and effects.

DOI:10.1049/ecej:19910031

出版商:IEE    

年代:1991

数据来源: IET

摘要:

Meteor burst communication systems are introduced with emphasis placed on the unusual propagation mode which they employ. The origin of meteors and their trails is reviewed and the trail characteristics relevant to communication systems described. The restriction on scattering geometries for viable transmission paths is exlained and the related footprint and hot-spot properties of meteor burst systems outlined. Meteor burst transmission loss is formulated in the conventional way as a modified bistatic radar equation and the origins of the modifying factor qualitatively explained. Meteor burst equipment, operating principles and applications are also briefly discussed. Finally, important quantities for assessing the performance of meteor burst systems are defined and typical values quoted.

DOI:10.1049/ecej:19910032

出版商:IEE    

年代:1991

数据来源: IET