DOI:10.1049/ree.1973.0078

出版商:IERE    

年代:1973

数据来源: IET

摘要:

A voting technique is used to diagnose fault conditions down to component level in a feedback control system using only the input-output cross-correlation function measured at suitable time delays. These time delays are chosen using a new formula based on Bayes's theorem, which ranks the time delays in order of usefulness in fault diagnosis; it can be readily applied at the design stage, thus assisting the integration of system design and test functions. The fault conditions necessary to set up the scheme may be obtained by direct fault generation in an actual system, or by simulation of the system mathematical model. A learning approach to the design of a fault diagnosis scheme is described which makes full use of any available failure data, together with the ranking formula for time delay selection, in the creation of an optimum scheme.Results obtained on a complex electro-hydraulic servo are presented which show that the scheme works satisfactorily in the presence of measurement noise and parameter drift, two factors which often cause a breakdown in conventional pattern recognition techniques. The computational requirements are extremely modest, and are well within the capacity of present day mini-computers proposed for use in automatic test equipment. In many instances, the scheme is suitable for manual and partially automated test sets, and can be used for fault diagnosis of a wide range of circuits and systems.

DOI:10.1049/ree.1973.0079

出版商:IERE    

年代:1973

数据来源: IET

摘要:

A travelling-wave dipole consisting of conventional arms with a resistanceRplaced atλ/4 from each end is analysed to enable a comparison of its signal/noise ratio with that of a standing-wave dipole of equal length to be made. Numerical results as a function of sky temperature are given when the dipole length is 3λ/2.

DOI:10.1049/ree.1973.0080

出版商:IERE    

年代:1973

数据来源: IET

摘要:

The matrix characterization of general fourterminal non-uniform transmission lines is derived by current and voltage gradient considerations and appropriate application of boundary conditions. The parameters allow ready simplification to any particular component cascade for any class of non-uniformities with solutions expressible in separable variables. By invoking the Principle of Duality, the corresponding immittance and transmission matrices of the dual structures can be simply written by inspection. Previous solutions are treated as special cases arid, in particular, a useful property of three-terminal autonomic lines is deduced.

DOI:10.1049/ree.1973.0081

出版商:IERE    

年代:1973

数据来源: IET

DOI:10.1049/ree.1973.0082

出版商:IERE    

年代:1973

数据来源: IET

摘要:

An expression for the sensitivity of a general second-order RC-active filter section to the finite gain-bandwidth product of the active elements (assumed to be first-order operational amplifiers) is derived and used to classify a number of well known active filter configurations according to the values of certain parameters of the general section. The circuits with a good high-frequency performance are found to have a high sensitivity to the values of passive components.

DOI:10.1049/ree.1973.0083

出版商:IERE    

年代:1973

数据来源: IET

摘要:

A large hybrid computer has been used to simulate modern communication systems, particularly those using digital radio techniques. This paper describes the basic thinking behind these models, outlines some of the techniques used and takes, as an example, a digital f.s.k. radio system. The unique results obtained, especially with regard to co-channel interference show the versatility and power of the simulation technique used.

DOI:10.1049/ree.1973.0084

出版商:IERE    

年代:1973

数据来源: IET

摘要:

The relationships between bit error probability and transmitter power are presented on a common basis for various binary and m-ary modulation schemes operating with the same system data rate. it is assumed that the channel is disturbed by additive white gaussian noise of fixed power spectral density and that optimal matched filter reception is used. the results presented allow a comparison of the efficiencies of the systems in the use of transmitter power to provide a specified bit error probability. the theoretical bandwidth requirements of each system have been considered. sometimes the system designer is constrained to the use of an existing channel of fixed bandwidth and signal/noise ratio. the choice of modulation system under these conditions has also been indicated.

DOI:10.1049/ree.1973.0085

出版商:IERE    

年代:1973

数据来源: IET

DOI:10.1049/ree.1973.0086

出版商:IERE    

年代:1973

数据来源: IET

DOI:10.1049/ree.1973.0087

出版商:IERE    

年代:1973

数据来源: IET