DOI:10.1049/ree.1983.0028

出版商:IERE    

年代:1983

数据来源: IET

摘要:

A modification to the matched filter is developed that enables a pulse compression radar system with inherently low sidelobes to be achieved. The system is illustrated using a signal with a truncated Gaussian spectrum with TB = 1000 giving sidelobes of −46 dB, mis-match loss of 0.002 dB and moderate tolerance to Doppler shift.

DOI:10.1049/ree.1983.0029

出版商:IERE    

年代:1983

数据来源: IET

摘要:

This paper describes methods for the serial transmission of data which have been developed and subsequently tested in practice during the course of experiments carried out over a 1000 km h.f. radio link. The methods include the use of adaptive equalization to combat the severe effects of channel-induced intersymbol interference and techniques for securing carrier and bit synchronization in the presence of intersymbol interference. In the system described, a probe pulse is imbedded into the data stream and use is made of the fact that the shortest signal path arising from multipath ionospheric reflections in the h.f. channel is on average the most stable of the multipaths. The presence of the probe signal reduces the data rate by 25%, but enables synchronization to be ensured in the presence of multipath and, furthermore, it enables the channel to be adaptively monitored for equalization purposes. In addition, it can be used to overcome system failure which is inherent in the use of decision-directed equalization operating in the presence of high levels of noise and multipath.

DOI:10.1049/ree.1983.0030

出版商:IERE    

年代:1983

数据来源: IET

摘要:

Electronic instruments should be immune to electromagnetic interference (e.m.i.) but must also be easy to use and service; the designer needs to resolve problems of conflicting interest. Several basic approaches to the e.m.i. problem are identified and practical ways of applying them are considered. Also discussed are the usefulness of Superscreened joints and cables, the importance of correct installation of connectors, and the need to reject unplated aluminium as a screening material. Two examples of e.m.i. immune instrument designs are examined with emphasis on practicality.

DOI:10.1049/ree.1983.0031

出版商:IERE    

年代:1983

数据来源: IET

摘要:

Possible uses of colour information in segmenting scenes for industrial scene analysis are outlined. Two algorithms for segmenting images using colour are described and the problems of using the resulting segmentation for interpreting images as three-dimensional scenes are discussed.

DOI:10.1049/ree.1983.0032

出版商:IERE    

年代:1983

数据来源: IET

摘要:

The paper describes a theoretical study of two different 19200 bit/s q.a.m. data-transmission systems suitable for use over voice-band telephone circuits. One of the systems employs a 64-point q.a.m. signal with an element rate of 3200 bauds, and the other employs a 256-point q.a.m. signal with an element rate of 2400 bauds. A near-maximum-likelihood detection process, derived from a reduced-state Viterbi-algorithm detector, is used at the receiver in each case. Results of computer-simulation tests are presented, comparing the tolerances of the two systems to additive white Gaussian noise, where the data are transmitted over models of four different telephone circuits. The effects, on the tolerance to noise, of inaccuracies in the estimates of the level and carrier phase of the received signal are also studied.

DOI:10.1049/ree.1983.0033

出版商:IERE    

年代:1983

数据来源: IET

摘要:

Machines that recognize isolated words from a small, predefined vocabulary have been commercially available for many years. The whole word pattern-matching principles used in these machines are described, and it is shown how these principles can be extended to deal with continuously spoken sequences of words. Details are given of the resulting connected word recognition algorithm which has several novel features and potentially useful extensions. The algorithm has already been implemented in real-time hardware, which will be used to explore the full potential and limitations of the method in many different applications.

DOI:10.1049/ree.1983.0034

出版商:IERE    

年代:1983

数据来源: IET