DOI:10.1049/ree.1980.0001

出版商:IERE    

年代:1980

数据来源: IET

摘要:

When the late Vebjorn Tandberg founded his company in 1933 to manufacture loudspeakers for wireless sets, he could hardly have expected that he would lead it through forty years of harmonious growth or that it would crash so spectacularly, and with so much acrimony and confusion. This paper describes the technical and financial background and suggests reasons for the course of events

DOI:10.1049/ree.1980.0002

出版商:IERE    

年代:1980

数据来源: IET

摘要:

This paper reviews current developments in the measurement of the immunity of receivers for sound radio and television broadcast reception from high-level ambient radio-frequency fields.The need for the control of immunity is justified by quoting examples of field strengths generated by authorized transmitters in which sound radio and domestic television installations are required to operate satisfactorily.The main attributes of standard methods of measurement, which may be adopted internationally are listed. The principal methods which are at present being considered are described and compared.It is shown that each has its limitations, but that by careful selection it is possible to conduct immunity measurements simply and with confidence over the frequency range 10 kHz to 1 GHz.

DOI:10.1049/ree.1980.0003

出版商:IERE    

年代:1980

数据来源: IET

摘要:

Several data compression methods are reviewed for signal and image digital processing and transmission, including both established and more recent techniques. Methods of prediction-interpolation, differential pulse code modulation, delta modulation and transformations are examined in some detail. The processing of two-dimensional data is also considered.Results of the application of these techniques to space telemetry and biomedical digital signal processing and telemetry systems are presented.Some of the considerations and comparison criteria presented, even though not completely general because extracted from experimental results, can be useful in selecting and defining the more pertinent data compression system for the different practical applications.

DOI:10.1049/ree.1980.0004

出版商:IERE    

年代:1980

数据来源: IET

摘要:

The microstrip waveguide model has been successfully applied to a host of elementary discontinuity problems generally encountered in microstrip circuits. However, until now the efficiency of the model has never been proved for more complex distributed microstrip structures such as multiple element filters, where both the amplitude and the phase of the computed scattering coefficients for the elementary discontinuity elements can be checked.In this paper it is shown the waveguide model may be used to design microstrip filters, taking into account the frequency dependent parasitic effects of any junction and discontinuity involved. The frequency dependent properties of the junctions and discontinuities considered can also be calculated by the quasi-static technique; as has been shown in many studies, the latter theory is restricted to lower frequencies. The quasi-static approach and the wave calculation obtained also suffer from the effect that radiation effects in the discontinuities have not been taken into account.

DOI:10.1049/ree.1980.0005

出版商:IERE    

年代:1980

数据来源: IET

摘要:

The transmission-line modelling (t.l.m.) method presents a new approach to the solution of lumped networks by providing discrete models for components. Errors become due to the modelling process only and not due to the approximate solution of an approximate calculus model. The correspondence between stub models and existing implicit methods is shown and the concept of numerical parasitic components as a means of assessing errors is introduced. The paper then describes the entirely new explicit routines resulting from transmission-line modelling and explains their use in non-linear circuits. Finally, examples of mixed implicit and explicit working are given for the solution of non-linear transistor circuits.

DOI:10.1049/ree.1980.0006

出版商:IERE    

年代:1980

数据来源: IET

摘要:

The paper deals with a new technique for the generation of r.f. signals for television testing. A signal generator tunable continuously through all the television bands is described. The operating principle is based on the generation of sound- and vision-modulated test signals at the standard intermediate frequency followed by broadband frequency conversion to the range 25 to 1000 MHz. The method is justified in a description of the technique of up-conversion to a high intermediate frequency with subsequent broadband down-conversion. This is followed by a presentation of the specification necessary for the local conversion oscillator, together with its operating principle and electrical characteristics. The method of frequency stabilization, indication and tuning is looked at in greater depth. In conclusion, the characteristics of the overall system are discussed, including a description of the modulator section, and the wide range of applications indicated.

DOI:10.1049/ree.1980.0007

出版商:IERE    

年代:1980

数据来源: IET

摘要:

The effects of base width modulation (‘Early effect’) on the d.c. and low-frequency incremental output characteristics of a bipolar junction transistor are reviewed critically, using only a basic consideration of the physical electronics of device operation. Attention is focused on the dependence on collector-base voltage of the majority carrier charge in the base of a device having an arbitrary base doping distribution. The conditions under which a single voltage parameter (‘Early voltage’) can be used to describe the output characteristics, independent of baseemitter drive conditions, are examined and some implications of the results to the circuit engineer outlined.

DOI:10.1049/ree.1980.0008

出版商:IERE    

年代:1980

数据来源: IET