DOI:10.1049/piee.1968.0001

出版商:IEE    

年代:1968

数据来源: IET

DOI:10.1049/piee.1968.0002

出版商:IEE    

年代:1968

数据来源: IET

摘要:

Real-time television signals were recorded on magnetic tape in digital form using an online, time-shared computer. A sampling technique was used to reduce the rate of incoming data, and the data were subsequently analysed to obtain the first- to fourth-order entropies. By inspecting the entropies it is seen that for low-detail pictures most redundancy is associated with the second-order probability density function, while for average- and high-detail pictures the redundancy is associated with higher-order statistics.

DOI:10.1049/piee.1968.0003

出版商:IEE    

年代:1968

数据来源: IET

摘要:

The paper describes a method for laying out networks by computer so that the number of crossings between the network connections is close to a minimum. The problem is relevant to the design of printed circuits, where special wiring arrangements have to be made when crossings occur. The network is expressed in the form of a permutation, which is convenient for manipulation, by deforming the network so that the node points lie on a straight line with the connections drawn as semicircles above an below the node line. Locally optimal networks are defined so that no gain can result from moving an individual node to a new position, and a 2-stage method of construction is proposed. The formulas used to calculate the number of crossings consist primarily of summations, so that the procedure is quickly performed on a computer. The method has been tested on some trial networks for which the minimum number of crossings is known, and it has also been compared with Monte Carlo methods on random networks. The results are encouraging in all cases.

DOI:10.1049/piee.1968.0004

出版商:IEE    

年代:1968

数据来源: IET

摘要:

A general method is described for solving the backboard-wiring problem. This problem is concerned with placing logic elements in an array of positions to minimise some function of the connection pattern such as total wire length. Any placement of the elements can be expressed as a permutation, and the proposed procedure determines a permutation which is optimal with respect to a given set of exchanges. It is thus possible to balance the quality of optimisation against the computational cost. The results show that simple sets of exchanges can offer marked improvements on a Monte Carlo search.

DOI:10.1049/piee.1968.0005

出版商:IEE    

年代:1968

数据来源: IET

摘要:

Theoretical methods of calculating the propagation coefficient of a rectangular waveguide with a narrow wall of semiconductor are discussed. Numerical solutions for a waveguide with a wall of germanium having resistivity in the range 0.1–100Ωcm have been made at 9.25GHz and confirmed experimentally for resistivities in the range 5–25Ωcm approximately. The technique is useful for the measurement of the complex permittivity of a semiconductor for the condition σ⋍ωε0εrand for the measurement of σ when σ> σωε0εr.

DOI:10.1049/piee.1968.0006

出版商:IEE    

年代:1968

数据来源: IET

摘要:

Designs of harmonic generators and detectors for several millimetre wavelengths are described, and detailed information is included on crystal and whisker treatments and junction formation. The voltage sensitivities of detectors and the conversion efficiencies of harmonic generators have been measured, and the relative merits of different crystal and whisker materials have been observed.

DOI:10.1049/piee.1968.0007

出版商:IEE    

年代:1968

数据来源: IET

摘要:

Wave-propagation properties of microstrip transmission lines can be determined accurately if an exact electrostatic-field solution can be found for a pair of charged conductors separated by a dielectric sheet. The latter problem is framed as an integral equation for whose solution simple numerical methods are available. To determine the kernel function of this integral equation, the classical method of images is generalised to include, multiple partial images; the kernel function is then given by well convergent infinite series. Wave impedances calculated using this theory yield very good agreement with experiment. Detailed results are given for the propagation velocity in microstrip lines with very thin strip conductors, and the method used to solve thick-strip problems is described.

DOI:10.1049/piee.1968.0008

出版商:IEE    

年代:1968

数据来源: IET

摘要:

A synthesis technique has been developed and a systematic realisation procedure has been presented for a general class of transformerless 4-terminal reactive networks without mutual inductances. The necessary and sufficient conditions for the applicability of this technique have been stated and the relevant theorems proved.With this technique it is possible to realise exactly a general class of fourth-order indefinite admittance matrices by networks of the series-parallel class. This synthesis procedure amounts to realisation of canonic sections and results in a simplified synthesis problem.The technique has been illustrated by means of examples of network realisations. The technique has also been applied to the problem of synthesis of a grounded 3-port network.

DOI:10.1049/piee.1968.0009

出版商:IEE    

年代:1968

数据来源: IET

摘要:

A method is presented for determining the transfer functions of phase-corrective networks of both minimum-phase and all-pass types. The method is based on manipulation of a class of polynomials containing one or more variable parameters, which is derived from Bessel polynomials and represents basically an extension of the application of Bessel polynomials and related Bessel functions to solving the problem of approximation to the ideal constant-group-delay characteristic. Some simple phase-correcting networks, useful in those applications where the phase distortion occurs mainly at high frequencies, are first discussed, and the formulas and graphs for the evaluation of their group-delay responses are given. The extension of the method to allow for determination of the transfer function of the correcting network matching a prescribed phase characteristic is then presented. Both maximally fiat and equal-ripple types of approximation are considered, and explicit formulas for the evaluation of the coefficients of transfer functions of ordern<6 are derived. The conditions on which the order of equalisation can be increased without affecting the complexity of the correcting network are also stated explicitly.

DOI:10.1049/piee.1968.0010

出版商:IEE    

年代:1968

数据来源: IET