DOI:10.1049/ecej:19920001

出版商:IEE    

年代:1992

数据来源: IET

摘要:

The corrugated horn has become the preferred choice of antenna for use in high-performance reflector antennas for communications, radar and remote sensing. The principles and attributes of corrugated horns are explained. The analysis, design and manufacturing techniques and types of horns in use are briefly discussed.

DOI:10.1049/ecej:19920004

出版商:IEE    

年代:1992

数据来源: IET

摘要:

Potential applications of high-temperature superconductors in electronics and communications are described with an emphasis on the relationship to the fundamental superconducting phenomena of zero resistance, magnetic-field expulsion and macroscopic quantum effects. The paper includes a description of the electric and magnetic properties of superconductors, potential microwave applications in filters, resonators, delay lines and superconducting transistors, and of mixers and other detectors. Simple logic circuits, an analogue-to-digital convertor and a SQUID magnetometer are also discussed, using the established conventional superconducting technology as reference point, and assessing the likely impact and importance of high-TCmaterials.

DOI:10.1049/ecej:19920005

出版商:IEE    

年代:1992

数据来源: IET

摘要:

Models of speech production and how these are used in text-to-speech conversion are reviewed. In the first part of the paper the foundation is laid for an explanation of present day speech synthesisers, and their limitations, through a phonetic description of speech production. The paper then presents a theorectical model of speech production which is the basis of most synthesisers. Next, a number of speech synthesisers are surveyed and their relative merits and shortcomings are considered. The paper ends with a brief look at techniques that are being used in place of the more traditional models of speech production in text-to-speech (TTS) systems and considers possible areas of progress in the future.

DOI:10.1049/ecej:19920006

出版商:IEE    

年代:1992

数据来源: IET

摘要:

European satellite communications are steadily growing but the same cannot be said of satellite TV, which has been the main driver so far. The number of satellite transponders in orbit will more than double in the next four years; satellite broadcasting, however, is moving into a period of consolidation but some uncertainty about the time needed for profitability of individual channels. Indecision about the regulatory framework for MAC transmissions and unknowns about the much-promoted high-definition TV do not make clear predictions possible. The emergence of business communication and links to Eastern Europe generally will diversify satellite communications. However, the dominance of the national telecommunication administrations will remain for some time, despite the European Commission's push for reregulation and the success of SES/Astra in direct-to home broadcasting.

DOI:10.1049/ecej:19920010

出版商:IEE    

年代:1992

数据来源: IET

摘要:

Conventional 3 cm entomological radars have been successfully used for many years to observe the migratory flight of the larger insect species, but the range at which these radars can detect individual small insects is limited to a few hundred metres. This paper outlines the design and application of an 8.8 mm wavelength radar to study the flight of insects weighing only 2 mg. Detection ranges in excess of 1 km were achieved for individual insects, and estimates of aerial density made by the radar were found to be within 50% of those made by an aerial sampling device.

DOI:10.1049/ecej:19920011

出版商:IEE    

年代:1992

数据来源: IET