摘要:

With the increase in the demand for high-quality sidescan sonar imagery of the sea-bed, there is a need for the development of fast and accurate computer techniques for the analysis of the survey information. The paper describes some techniques that have been developed to perform operator-assisted and fully automated classification of sidescan sonar images of the sea-bed on the basis of sediment texture. Special reference is made to the usefulness of the fractal model for the analysis and synthesis of textures.

DOI:10.1049/ecej:19910034

出版商:IEE    

年代:1991

数据来源: IET

摘要:

Smart cards, or IC cards, have recently begun to appear in many applications, e.g. banking, telephony and TV decoders. So far their use has been restricted to a set of very specific purposes. However, a smart card contains a microprocessor and a memory, so that it can be used for many functions that are presently performed by other devices, such as papers, keys, purses and also, sometimes, other computers. Smart cards provide a high level of security and enable a new family of information systems to be designed. 100 million IC cards will be manufactured in 1991 throughout the world. The paper is both a survey of the existing technology and an attempt to describe some future possibilities.

DOI:10.1049/ecej:19910036

出版商:IEE    

年代:1991

数据来源: IET

摘要:

Current meteor burst communication systems operate at constant bit rates of 4 kbit/s and are limited to average throughputs of 50 bit/s. The paper documents the design and implementation of an adaptive-bit-rate modem for optimising the throughput. A novel extension of differentially encoded binary phase shift keying is proposed so that two frequency division multiplexed baseband channels can be transmitted: a main channel for the data and an auxiliary channel for conveying bit rate change information. In this way, two modems, one at each end of the link, can automatically adapt to a new operating speed without the intervention of a host computer. The results prove that the two channels can operate independently with minimal mutual interference. A theoretical improvement in bit rate of 18 times over the fixed-bit-rate modem is possible.

DOI:10.1049/ecej:19910037

出版商:IEE    

年代:1991

数据来源: IET

摘要:

Over the past few years, facsimile has become the most popular form of business text communication. The paper gives a brief outline of the way in which a facsimile terminal operates and explains the various scanning and printing technologies in use today. The use of facsimile on the integrated services digital network (ISDN) is considered also.

DOI:10.1049/ecej:19910038

出版商:IEE    

年代:1991

数据来源: IET

摘要:

Work on radar systems for cars has been going on since the 1950s, but that earlier work did not lead to practical products. The paper reviews some of that earlier work, and shows how recent technological advances have now made automotive radar practical. It also shows some results obtained from current work in this field.

DOI:10.1049/ecej:19910039

出版商:IEE    

年代:1991

数据来源: IET