摘要:

On 1st January 1990 small but significant changes were made to the UK's electrical standards to bring them more closely into line with the ideal definitions of the International System of Units (SI). Similar changes were made simultaneously by other countries resulting in much improved harmonisation of electrical measurements worldwide. Although the major impact of such changes will be felt by those making high-accuracy measurements, it behoves all users of electrical measuring instruments to be aware of the situation and to consider whether any action is required on their part.

DOI:10.1049/ecej:19900040

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Fibre-optic sensor technology provides a means of performing sensing functions in hostile environments, such as explosive or high electromagnetic-interferenceprone areas, whilst also offering advantages in terms of convenience of application. For these reasons fibre-optic sensors are currently of great interest to large sections of the industrial and military community. The paper presents a selection of the sensor systems upon which Plessey Research has worked in recent years and which illustrate this wide interest. The fibre-optic gas sensor and the fibre-optic distributed temperature sensor are examples of sensors with general industrial interest. The analogue spectral-filtering sensor system and the fibreoptic gyroscope are of interest to the aerospace industry. The hydrophone has potential naval applications whilst fibre-optic evanescent field sensors have an attraction to medical and industrial users. For each of these sensor types the principle of operation and the demonstrated performance are described and the current state of development commented on.

DOI:10.1049/ecej:19900042

出版商:IEE    

年代:1990

数据来源: IET

摘要:

FM radars represent one of the oldest and simplest–yet at the same time one of the most versatile types of radar. The paper presents a tutorial review of the basic principles of FM radars and introduces a number of new ideas, including digital generation of wideband linear FM waveforms, and aperture synthesis with FM radar.

DOI:10.1049/ecej:19900043

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The advantages of standard bus systems have been appreciated for many years. The ability to connect only those modules required to perform a given task has both technical and commercial advantages over a system with a fixed architecture which cannot be easily expanded or updated. Although such bus standards have proliferated in the microprocessor field, a general purpose low-cost standard for digital video processing has yet to gain acceptance. The paper describes the likely requirements of such a system, and discusses three currently available commercial systems. A new bus specification known as Vidibus, developed to fulfil these requirements, is presented. Results from applications already implemented using this real-time bus system are also given.

DOI:10.1049/ecej:19900044

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The yearly average number of airliners reported, worldwide, as having been involved in a mid-air collision is less than two. Air traffic control (ATC) aims to hold this rate, despite future traffic growth. Improvements in air-ground communications, e.g. by the use of selectively addressed secondary surveillance radar (SSR Mode S), make possible surveillance of the air situation by ATC computers, thus trapping potentially dangerous discrepancies between ATC plans and reality. The necessary level of confidence makes it unlikely that computers will soon take over from human pilots or controllers. However, as computers are prone to different errors than those of humans there is a good case for mechanised redundancy to assist ATC decision taking.

DOI:10.1049/ecej:19900045

出版商:IEE    

年代:1990

数据来源: IET