摘要:

Over the past century, Scotland has contributed greatly to the electrical engineering profession, numbering among its sons the likes of Lord Kelvin, James Clerk Maxwell, Alexander Graham Bell, John Logie Baird and Alan Campbell Swinton. Remarkably, it was the need for female assembly labour in the last War that led Ferranti plc to manufacture its gyroscopic gunsights in Edinburgh and give birth to the Scottish electronics industry alongside Barr & Stroud, whose origins stretch back to the times of Lord Kelvin. The long-standing affinity of Scotland with the United States then rapidly led several US multinational enterprises to select Scotland for the manufacture of electromechanical business machines and thereby to access European markets. The Toothill Report in 1961 of the independent Scottish Council (Development & Industry) focused Government policy very successfully on restructuring the Scottish economy away from the traditional industries and towards creating science-based, technically oriented industries. This policy was helped out with electronics by the unexpected discoveryof hugy North Sea oil reserves. Microelectronics has figured prominently since the early 1960s, and today some 21% of all merchant European ICs are manufactured in Scotland, giving rise to the phrase ‘Silicon Glen’. The vulnerability of the Scottish electronics industry to market forces, technological change and external decision marking led to considerable difficulties in the mid-1970s. Fortunately, the early 1980s have seen the growth the 1960s return in inward investment, due largely to the efforts of the Scottish Development Agency; and a number of entrepreneurial operations have reached maturity, with many more in the start-up phase, addressing new electronic andinfromation technology markets. Today, some 43000 people are employed is Scottish electronics, and product output is approaching £2 billion per annum. Most importantly, the industry is now well structured and highly interactive internationally as well as with the large local financial community and higher education sector. This address reviews the evolution of the Scottish electronics industry by concentrating on the role of Ferranti and case studeis of successful ventures by US multinational and entrepreneurial enterprises.

DOI:10.1049/ip-f-1.1986.0002

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The transmission characteristics of the usual two- and three-pulse feedforward cancellers have certain properties such as narrow clutter notch and uneven transmission region which may be undersirable in many applications. Recursive filters need multipliers and may be too expensive if large quantities of filters are required. The paper presents a class of multiper-free digital recurisive filters for ground clutter suppression which combine desirable transmission characteristics with low cost. The filters are particularly designed for a CW radar with peformed fixed beams. The usual problems associated with the infinite impulse response of recursive filters therefore do not occur.

DOI:10.1049/ip-f-1.1986.0003

出版商:IEE    

年代:1986

数据来源: IET

摘要:

Through mainly numerical studies, some criteria of performance have evolved which offer a means of alternative comparisons of spectral efficiency other than or in support of the more traditional forms. Modulation schemes considered in the paper are single-hcontinuous phase FSK and multimode (h) partial-response FSK (MHPR). Suggested performance codes are given governing the efficiency of the stipulated criteria.

DOI:10.1049/ip-f-1.1986.0004

出版商:IEE    

年代:1986

数据来源: IET

摘要:

An analytic solution to the intersymbol interference and timing jitter suppression problems for optimal realisable data transmission filters is presented. By analysing the performance of several practical filters, a design graph and a mathematical expression giving the relationship between bandwidth, degree of filter and percentage eye closure are given.

DOI:10.1049/ip-f-1.1986.0005

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A new closed-loop autocorrelation system is proposed in the paper. It is based on a conventional autocorrelator; however, the fixed delay is replaced by a variable delay line and the autocorrelator output is fed back to control the delay. The variable delay can be realised by a SAW voltage-controlled variable delay line (VCDL). Adetailed analysis of the loop is given. It is shown that for some special inputs, the loop performs as a frequency-measuring system, as an instantaneous frequency measurement (IFM) or as a wideband linear FM discriminator. It is further shown that, in the presence of noise, the loop behaves similarly to a frequency modulation feedback (FMFB) loop. Therefore, the output SNR can be improved (in comparison with conventional FM discriminators) by appropriately choosing the loop parameters. Experimental results of a system implemented using an SAW VCDL are presented and are shown to support the analysis.

DOI:10.1049/ip-f-1.1986.0006

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A reduced search soft-decision decoding algorithm for binary block codes is presented. It is based on the weight distribution of the code and the transition probabilities of a binary inputQ-ary output channel in sequencing the codeword classes during a table look-up operation. An upper bound is presented for the decoding time improvement factor of the reduced search algorithm compared to exhaustive table look-up decoding.

DOI:10.1049/ip-f-1.1986.0008

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The paper deals with the problem of radar detection of a target echo embedded in log-normal clutter and white Gaussian noise. Relevant features of this article, with respect to previous papers on the same subject, refer to the coherent model assumed for the clutter and the processing chain. In more detail, the in-phase and quadrature components of clutter have been modelled to give a log-normal amplitude distribution and a near uniform distribution of the phase. Any shape of the correlation among consecutive clutter samples is also allowed in the model. At the same time, the processing chain is also coherent, i.e. it operates on the two components of the signals. Two architectures have been considered for the processor. The first, used in current practice, is formed of a linear transversal filter (for the clutter attenuation and the target echo enhancement) cascaded with a quadratic envelope detector and a comparison with a suitable threshold. The second processor considered differs from the previous one in the filter for clutter cancellation. A nonlinear homomorphic filter has been conceived to obtain a better suppression of clutter. The detection performance of the two processing chains have been evaluated, by means of computer simulation, in a number of operational cases of intrest. The paper gives a first contribution to the problem of finding better models of disturbance and of deriving more efficient processing chains.

DOI:10.1049/ip-f-1.1986.0009

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A theory of the distributed detection of radar targets is developed. The radar system employs a number of physically separated peripheral receivers and detectors and a central processor that provides a final decision by combining peripheral decisions rather than decision statistics. Various combining strategies are studied in the context of overall system optimality. It is shown that the optimal decision strategy of a peripheral detector depends on the strategies of the other peripheral detectors and, interestingly, on the structure of the central processor. To illustrate application of the theory, the design of a distributed system in a Rayleigh fading environment is studied.

DOI:10.1049/ip-f-1.1986.0010

出版商:IEE    

年代:1986

数据来源: IET

摘要:

Design procedures for constructing complementary binary sequences and co-operative binary sequences are available in the literature. In the paper an algorithm for constructing pairs of ternary sequences which are co-operative not only in the autocorrelation domain but also in the signal domain (and hence called ‘doubly’ co-operative) is presented. The two signals can be transmitted as if they are a single sequence with energy efficiency of 100% and with appreciably large co-operative merit factor. Good co-operative pairs of sequences up to length 29 are reported.

DOI:10.1049/ip-f-1.1986.0011

出版商:IEE    

年代:1986

数据来源: IET

摘要:

For improved performance of a predictive coding system used for encoding picture signals at low bit rates, it is necessary to design not only an efficient predictor, but also an efficient quantiser that produces minimum perceptible distortion. We have described in the paper a scheme in which a special quantiser called a ‘centre-clipping quantiser’ (CCQ) is used in a ratio PCM coder. The subjective quality of the picture at 1.58 bit/pel is similar to that of an ADPCM coder at 3 bit/pel, giving an advantage of more than 6 dB in performance.

DOI:10.1049/ip-f-1.1986.0012

出版商:IEE    

年代:1986

数据来源: IET