By Topic

Radio and Electronic Engineer

Issue 9 • Date September 1973

Filter Results

Displaying Results 1 - 10 of 10
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fault diagnosis using time domain measurements

    Page(s): 523 - 533
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1324 KB)  

    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. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Signal/noise ratio of travelling-wave dipole

    Page(s): 534 - 536
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (261 KB)  

    A travelling-wave dipole consisting of conventional arms with a resistance R placed at¿/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 3¿/2. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Matrices for dual representation of four-terminal non-uniform transmission lines

    Page(s): 537 - 544
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (865 KB)  

    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. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Colloquium report: electrical connectors

    Page(s): 545 - 546
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (311 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The effect of amplifier gain-bandwidth product on the performance of active filters

    Page(s): 547 - 552
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (583 KB)  

    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. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Hybrid computer simulation applied to digital communication systems

    Page(s): 553 - 561
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1208 KB)  

    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. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A comparison of modulation schemes for binary data transmission

    Page(s): 562 - 568
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (822 KB)  

    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. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • The 47th annual report

    Page(s): 570 - 587
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2368 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.