DOI:10.1049/ree.1983.0035

出版商:IERE    

年代:1983

数据来源: IET

摘要:

This paper describes the results and conclusions from a two-year field evaluation programme of 11 GHz 140 Mbit/s q.p.s.k. digital radio relay equipment conducted on three hops in the UK by British Telecom. In the first part of the paper the general features of system performance are described, including month-by-month outage results, error distributions, outage event durations, and error-free-secondperformance. The relative effect on performance of rainfall attenuation and multipath propagation are illustrated and discussed, together with effects of variations in hop length and the use of height diversity facilities. Worst-month outage results are compared with CCIR performance requirements to determine planning criteria for diversity.The second part describes in detail the system behaviour during multipath conditions, and examines whether the outage primarily resulted from noise, interference, or distortion conditions. The signature method of characterizing tolerance to distortion is described in order to explain observed results, and the effect of adaptive equalizer techniques is examined. Finally results from the evaluation of an automatic slipless protection switching system are presented, showing probability of slipless operation and performance improvements achieved in multipath conditions.

DOI:10.1049/ree.1983.0036

出版商:IERE    

年代:1983

数据来源: IET

摘要:

The paper provides the background which caused the UK Ministry of Defence to introduce an information retrieval service based on information technology techniques. The decision process leading to a system specification is outlined and the specification arrived at detailed. The method adopted to procure the system is described followed by details of the systems performance after installation. Finally the conclusions reached from operating the system are given.

DOI:10.1049/ree.1983.0037

出版商:IERE    

年代:1983

数据来源: IET

摘要:

A high-speed, microprogrammed adaptive filter implementation using the AM2900 bit-slice devices and a hardware multiplier-accumulator is described. The implementation is based upon a clipped least-mean-square adaptation algorithm. The structure of the filter and its performance are presented.

DOI:10.1049/ree.1983.0038

出版商:IERE    

年代:1983

数据来源: IET

摘要:

This paper presents tables of group-delay functions, ranging in order from 3 to 11, which approximate a nominal one second delay over bandwidths up to 17.5 rad/s. The functions, which can be arranged in all-pole or non-minimum phase forms, are based on a least-squares minimization of the delay error and therefore exhibit ‘unequal ripple’ characteristics. These and other features of the leastmean-square approximations are discussed and comparisons drawn with maximally-flat and equi-ripple forms.A versatile RC-active biquadratic section, which has been found particularly useful in implementing non-minimum phase functions, is also described.

DOI:10.1049/ree.1983.0039

出版商:IERE    

年代:1983

数据来源: IET

摘要:

The widespread use of modular construction in the electronic equipment industry has resulted in the development of standard electronic modules (SEMs). These units are an extension of the original modular partitioning concept, and are designed for universal use, being interchangeable between different items of SEM equipment. They are highly reliable functional modules which may be discarded on failure, and are designed to be independent of manufacturer or technology level. As a consequence of their development, this paper describes the use of life cycle cost modelling in the design and evaluation of competing SEM/non-SEM modular systems.

DOI:10.1049/ree.1983.0040

出版商:IERE    

年代:1983

数据来源: IET

摘要:

This paper describes the recording and replaying of digital video signals using a computer-type disc-drive as part of a system being developed to enable animated picture sequences to be generated for television, where at present film is used.The characteristics of the disc-drive are described together with data processing, error protection and signal synchronization systems which enable digital televisionYUVcomponent signals, sampled at 12 MHz, 4 MHz, 4 MHz respectively, to be recorded and replayed in real time.

DOI:10.1049/ree.1983.0041

出版商:IERE    

年代:1983

数据来源: IET