摘要:

Digital microwave radio communication offers high-fidelity transmission but it is susceptible to multipath propagation effects. The paper distinguishes between the minimum phase and nonminimum phase fade types and presents simulations illustrating typical radio performance during fades, before introducing various adaptive filter designs for implementing the equaliser to compensate for these two fade types. The expected performance of these equalisers is further investigated via simulation and by a prototype practical design

DOI:10.1049/ecej:19900003

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The United Kingdom is about to enter a new and exciting phase of its broadcasting history. On 27th August 1989 a satellite was launched for the world's first high-power direct broadcasting by satellite (DBS) service which is funded entirely privately. For the success of this service the broadcaster needs to establish a large customer-base quickly and yet needs to offer the potential of receiver improvements for the future. Against this background the D-MAC/packet system has been adopted as the signal format to be used. This system offers a reception option involving a relatively inexpensive set-top convertor and yet it also provides a number of important options for enhancing the service. The paper briefly describes the D-MAC transmission system and highlights in particular how it can provide an evolution to high-definition television (HDTV) in the future.

DOI:10.1049/ecej:19900004

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Radars and their associated antennas evolved more or less independently for a number of years, but a gradual marriage began in the 1960s with the advent of improved and relatively cheap signal-processing techniques. Today's advanced radars with electronically-steered beams, incorporating T/R modules and signal-processing equipment at the array elements, appear to be the realisation of the early pioneers' pipe dreams. Is it all necessary and where will it end? This second part of the paper discusses the more important antenna characteristics affecting radar system design and concludes with a brief review of the current state of the art and an indication of future trends.

DOI:10.1049/ecej:19900005

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Computer and data networks are the interconnection technology for information systems. Information systems require networks which can transfer data in a rapid and reliable manner. These networks are controlled by protocols, which represent the rules for the transfer of the information around the network and which must be capable of responding to problems that are both expected and unexpected. The specification and standardisation of communication protocols has a significant commercial impact on users and so there is considerable international collaboration to provide new technologies and networks that will evolve to replace the current networks. The paper reviews the ways in which this specification and standardisation is being applied to the protocols which support the current and future generations of networks, and introduces the Open Systems Interconnection sevenlayer Reference Model.

DOI:10.1049/ecej:19900009

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Research on autonomous vision-guided vehicles has received attention from several groups worldwide. This paper describes the ongoing research at the University of Bristol to explore mobile robot road-following algorithms and suitable hardware architectures to run these algorithms. The prototype hardware, designed and built at the University, is a real-time frame grabber system based on transputers. Two approaches to real-time road edge following that have been tested to guide a small tracked vehicle around the paths of the University gardens are described.

DOI:10.1049/ecej:19900010

出版商:IEE    

年代:1990

数据来源: IET