摘要:

The application of digital differential analyser principles leads to a convenient and straightforward way of digitally generating a hyperbolic (height-corrected) time base suitable for the display in a terrainsurveying radar or sonar. The method avoids the use of the operations of multiplication (other than by shift), division and square root.

DOI:10.1049/ij-ecs.1977.0008

出版商:IEE    

年代:1977

数据来源: IET

摘要:

An implementation of ternary memory elements is presented. Different synchronous triflops are described and their experimental realisation is discussed. Also asynchronous memory elements based on the self-synchronisation of synchronous triflops are introduced. These triflops have been selected in order to have flexible ternary memory elements with simple excitation equations.

DOI:10.1049/ij-ecs.1977.0009

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A preliminary investigation has been made of a multiband noise-reduction system which uses a time-shared frequency-modulated narrow-band pilot tone. Signal-path delay allows anticipation of the control signal, and enables transient distortion to be eliminated. Discrete-level encoding is shown to have several important advantages, and, in the system described, the compression range is 24 dB in 6 dB steps. Crosstalk between the signal bands is minimised by dynamic adjustment of the filter bandwidths.

DOI:10.1049/ij-ecs.1977.0010

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A set of equations has been derived which describes the steady-state oscillations of any nonlinear device with a loopless current/voltage characteristic in any frequency-dependent circuit. The equations are expressed in terms of the amplitudes of the waveform harmonic components, the admittances or impedances at the harmonic frequencies, and the time-averaged integrals of the derivatives of the oscillation voltage and current.

DOI:10.1049/ij-ecs.1977.0011

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The paper considers various iterative detection processes that are suitable for use in a synchronous serial data-transmission system in which a q.a.m. signal is fed over a telephone circuit or h.f. radio link at a transmission rate of up to 20 000 bits/s. Reasons are first given for the study of q.a.m. systems. The methods of operation of the different detection processes are then described, and, finally, the results of computer simulation tests are presented, comparing the tolerances of the detection processes to additive white Gaussiannoise with the tolerance of a nonlinear equaliser of optimum design. Several different time-invariant channels are used in the tests. It is shown that a relatively simple detection process can achieve a useful improvement in tolerance to noise over the nonlinear equaliser.

DOI:10.1049/ij-ecs.1977.0012

出版商:IEE    

年代:1977

数据来源: IET

摘要:

Tight worst-case error bounds are derived for the results of the fast Fourier transform (f.f.t.). The following f.f.t. algorithms are analysed:(i) standard method of complex multiplication without scaling(ii) standard method with prescaling(iii) standard method with stagewise scaling(iv) Buneman's method of complex multiplication without scaling(v) Buneman's method with prescaling(vi) Buneman's method with stagewise scaling.The results establish the maximum number of least-significant bits which can become noisy in the computed spectrum for a given numberNof data points, a given accuracy in the arithmetic, and a given accuracy in the tabulated coefficients of the f.f.t. The results are compared with the r.m.s. errors obtained earlier from statistical considerations.2,3The comparison indicates that the worst-case values cannot be extrapolated from the r.m.s. values, since their dependence onNis different.

DOI:10.1049/ij-ecs.1977.0014

出版商:IEE    

年代:1977

数据来源: IET