摘要:

The system user must be satisfied that frequency domain data adequately measures the quality of his system in all the performance aspects of interest. This involves the interpretation of transfer functions other than system output/input, and the acquisition of data over a wide frequency band ranging from a few percent of bandwidth to several multiples of bandwidth, the latter for the detection of secondary resonances. However, only a few spot frequencies need be chosen to ensure that system response to actual operational signals is adequate. Careful selection will also maximize the diagnostic potential of the measurements. In noisy systems the measurement time for adequate confidence in gain and phase observations must be established before the test routine can be automated.

DOI:10.1049/ree.1971.0017

出版商:IERE    

年代:1971

数据来源: IET

摘要:

To compare errors arising in a measuring instrument from drift and low frequency (1/f) noise, the behaviour of the latter in the time domain is calculated. The standard deviation is expressed in terms of the cut-off frequency and integration time of the instrument, and the frequency index of the noise, which can be measured at audio frequencies. Optimum values of these quantities are discussed. The theory is illustrated by reference to measurements on m.o.s. transistors which indicate that current noise may sometimes be the main cause of ‘drift’ for periods between a day and a year.

DOI:10.1049/ree.1971.0018

出版商:IERE    

年代:1971

数据来源: IET

摘要:

Given the polynomial in s which describes the reciprocal of the transfer function of the circuit to be synthesized, the recurrent determinant may be determined. The continuant determinant is evaluated by a logical sequence of operations on the recurrent determinant. The values of the elements of the continuant determine either the gains of the amplifiers in the circuit when the component values are specified or the component values when the amplifier gains are specified. The reverse procedure of producing the recurrent from the continuant is also described and from the recurrent the reciprocal of the transfer function of the network may be obtained.

DOI:10.1049/ree.1971.0019

出版商:IERE    

年代:1971

数据来源: IET

摘要:

This paper describes the requirements of digital equipment testing and describes a test system, controlled by a digital computer, capable of testing a wide variety of digital equipment.

DOI:10.1049/ree.1971.0020

出版商:IERE    

年代:1971

数据来源: IET

摘要:

Efficiency of the two-frequency moving target indication (m.t.i.) radar system is considered under the assumption that the echo and clutter signals are stochastic processes, and clutter spectrum is Doppler-shifted. Single and double cancellation circuits are investigated. The analysis indicates a fairly good tolerance of the system efficiency to clutter drift, especially when double cancellation is used.

DOI:10.1049/ree.1971.0021

出版商:IERE    

年代:1971

数据来源: IET

摘要:

In order to extend v.h.f. coverage in Great Britain to areas of relatively poor reception, the Independent Television Authority has recently commissioned a number of hybrid solid-state/valved combined signal working relay stations. Whilst this has led to a high level of performance and reliability, the use of combined signal working has introduced problems peculiar to this system in so far as the measurement of linearity is concerned.The paper describes a typical relay system and the methods of expressing the linearity requirements in terms of intermodulation and cross modulation are defined, together with the empirical relationship between cross-modulation degradation and the standard subjective severity scale.

DOI:10.1049/ree.1971.0022

出版商:IERE    

年代:1971

数据来源: IET

摘要:

An experiment is described in which a focused image of objects within a solid material was obtained from signals received at a transducer array on the material surface. Image construction from these data was done by digital computer. The results conform to the theoretical resolution obtainable under the prevailing physical constraints.

DOI:10.1049/ree.1971.0023

出版商:IERE    

年代:1971

数据来源: IET