摘要:

The paper describes the operation of the multi-tanh circuit as it applies to triangle-to-sine conversion. The treatment includes a detailed examination of the properties of the transfer function of the circuit, an evaluation of total harmonic distortion with circuit parameters chosen to minimise total harmonic distortion.

DOI:10.1049/ij-ecs.1979.0015

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The effect of nonideal operational-amplifier output impedance on active-filter pole displacement or pole variation, respectively, is discussed and compared with the effects of finite amplifier gain and gainbandwidth product. The analysis shows that the pole variation is mainly dependent on three factors: the gain-sensitivity product, the pole frequency rated with the gain-bandwidth product, and the amplifier output resistanceRAas compared to the network impedance levelR∞. The influence of the amplifier output impedance on the total pole shift can be varied, within some practical and technological limits, by the choice of the impedance levelR∞. The results have been verified experimentally.

DOI:10.1049/ij-ecs.1979.0016

出版商:IEE    

年代:1979

数据来源: IET

摘要:

An effective synthesis procedure is presented for the design of broadband microwave amplifiers using GaAs f.e.t.s. Based upon Youla's theory of matching, the equivalent input and output impedances of the GaAs f.e.t. are equalised to resistive source and load by lossless networks to achieve thenth order Cheby̅shev and Butterworth bandpass transducer power gain responses. The matching networks can also be designed to compensate for the gain rolloff of the GaAs f.e.t. which is approximately 6 dB/octave. The synthesis produces lumped lossless matching networks which can be approximated by distributed networks to a very good extent for 40% bandwidth or less. Examples are presented to illustrate the effectiveness of the synthesis procedure.

DOI:10.1049/ij-ecs.1979.0017

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The paper discusses, both mathematically and systematically, a typical 4-port equispaced (over 360°) antenna amplitude-comparison direction-finding system which operates over a wide microwave bandwidth. System components are examined in terms of their effect on performance and methods for reducing errors are discussed. A simple example of using a stored-calibration process is presented and it is shown that errors in measuring bearing can be reduced by at least 20% when using stored-calibration methods.

DOI:10.1049/ij-ecs.1979.0018

出版商:IEE    

年代:1979

数据来源: IET

摘要:

This paper deals with the calculation of systematic time jitter in a self-timed regenerative repeater, where the timing circuit consists of a square-law device followed by a high-Qresonant circuit tuned to the transmission rate and a down zero-crossing detector. The method presented here can be used for any linecoding scheme and waveshape of finite duration. Some interrelations between the selected line code and waveform are also studied for the given timing recovery circuit. Examples for different waveforms and codes of practical importance are presented.

DOI:10.1049/ij-ecs.1979.0019

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The cascade realisation ofRCactive filters is compared with high-order single-amplifier realisations with respect to the gain-sensitivity product. As a result it is shown that this figure of merit is proportional tonQfor cascade realisations and toQnfor single-amplifier circuits realising the same transfer function of degree 2n.

DOI:10.1049/ij-ecs.1979.0021

出版商:IEE    

年代:1979

数据来源: IET

摘要:

This paper describes a theoretical investigation of idle-channel noise in p.c.m. sound-signal systems and presents the results of measurements made on a high-quality (13 bits per sample linear) p.c.m. soundsignal distribution system.The amplitude probability distribution and power-density spectrum of idle-channel noise are theoretically derived, including the complication introduced when dither is used. It is found that the statistics of idlechannel noise, with or without dither, are not Gaussian and show a strong dependence on the statistics of the noise present at the coder input. The spectrum of idle-channel noise is expected from theory to be essentially flat for equipment both with and without dither, but in practice quantised hum components weight the spectrum.The results of the measurements show satisfactory agreement with those predicted from theory. It is concluded that, of the various types of measurement made, the results given by a quasi-peak-reading meter preceded by a noise-weighting network give the best assessment of the subjective annoyance caused by idlechannel noise.

DOI:10.1049/ij-ecs.1979.0022

出版商:IEE    

年代:1979

数据来源: IET

摘要:

Development of a flexible digital correlator is described, suitable for the generation of both crossand auto-correlation functions from bandlimited signals up to 5 kHz. The resulting instrument is a 100 points, 10 kHz sampling rate, 8 bit data word correlator; it can be used in series or parallel combinations. Some preliminary data are provided on its application as a digital filter.

DOI:10.1049/ij-ecs.1979.0023

出版商:IEE    

年代:1979

数据来源: IET

摘要:

A rate-7/8 self-orthogonal convolutional-code implementation is discussed. The codec uses a majority logic threshold technique for decoding the encoded data stream. The error performance of the code in a binary symmetrical channel in presence of white Gaussian noise is investigated and the input/output bit error-rate bound for the codec is computed and compared to another 7/8-rate codec that has already been implemented.

DOI:10.1049/ij-ecs.1979.0024

出版商:IEE    

年代:1979

数据来源: IET

摘要:

In this paper a computational algorithm is derived for the determination of the moments of the time between failures for a class of repairable systems whose components have prescribed failure distributions. Such systems are generally non-Markovian and the approach adopted here approximates system behaviour by application of the method of stages. Computation of the first moment (the mean time between failures), for the class of systems considered, was posed as an unsolved problem in an earlier issue of this journal.

DOI:10.1049/ij-ecs.1979.0025

出版商:IEE    

年代:1979

数据来源: IET