摘要:

This is the second of two papers introducing the main topics in digital signal processing. The subject of this paper is the estimation of the spectra of signals and both classical estimation methods and modern model-based methods are discussed. These techniques are compared and results are presented which demonstrate the superior resolution which is obtained with modern autoregressive spectral analysis methods. Examples are given of the application of these techniques in the areas of speech processing and biomedical signal analysis.

DOI:10.1049/ecej:19930039

出版商:IEE    

年代:1993

数据来源: IET

摘要:

Optical technology is already the dominant carrier of global information. It is also central to the realisation of future networks which have the capabilities demanded by society. For example, essentially unlimited bandwidth to convey services of any kind, full transparency that allows terminal-only upgrades in capacity, and flexible routeing of channels are some of the key features that cannot be provided by alternative technologies. In the main, all of the necessary elements for such networks already exist in experimental form, and rapid progress is being made towards a field deployment capability. This will bring about a paradigm change in the whole nature of telecommunications as we move into the third millennium.

DOI:10.1049/ecej:19930040

出版商:IEE    

年代:1993

数据来源: IET

摘要:

For some years now, ‘fractals’ have provided spectacular displays (which have seemingly hypnotised both the popular technical press and the ‘media’) on computer workstations equipped with high-power graphics processors, and also provoked much controversy with regard to their potential for mimicking real-world imagery. In this paper the authors briefly describe the theoretical background of fractal representations and investigate in more detail the validity of such an approach for applications in natural scene portrayal and coding.

DOI:10.1049/ecej:19930041

出版商:IEE    

年代:1993

数据来源: IET

摘要:

Coded modulation has had a very significant impact on the communications scene in the decade or so since its introduction, finding practical applications from voice-band modems for telephone lines to deep-space communications. The paper introduces the principles of coded modulation and describes the two main schemes: block coded modulation (BCM) and trellis coded modulation (TCM). In particular it considers the argument between the proponents of BCM and TCM, and points out some pitfalls in the use of performance measures such as asymptotic coding gain for these schemes. It concludes that in terms of performance versus decoder complexity the schemes seem to be quite close, and the choice of the system designer may be determined by other factors.

DOI:10.1049/ecej:19930042

出版商:IEE    

年代:1993

数据来源: IET

摘要:

There is an increasing emphasis to extend the services available on fixed telecommunication networks to the mobile user. One area of the RACE 1043 project examined the possibility of universal mobile services within future integrated broadband communications networks. Essential to the feasibility of such a scheme is an understanding of the wideband characteristics of the radio channel. The article describes the results of a wideband channel sounding programme conducted at 39 and 60 GHz, together with a channel-modelling exercise based on these measurements, aimed at producing a statistical model of the wide band millimetric channel.

DOI:10.1049/ecej:19930043

出版商:IEE    

年代:1993

数据来源: IET

摘要:

Introduction of the European EMC Directive has made it very important that engineers design for EMC in their productsfrom the start. The paper describes a strategy to ensure that EMC aspects of design are considered in a logical sequence during development. This strategy is discussed, checklists for EMC design are introduced and a number of important design areas highlighted.

DOI:10.1049/ecej:19930047

出版商:IEE    

年代:1993

数据来源: IET