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1887

Radio and Electronic Engineer

Volume 51, Issue 9, September 1981

Volumes & issues:

Volume 51, Issue 9

September 1981

James Clerk Maxwell 1831–1879
Oscillator design
Multi-discplinary engineering in the process industries
Correction: Integrated optics: a tutorial review
Function generator review
Microprocessor-based digital filters
Pseudo-linear operation of second-order phase-locked loops
  • Author(s): J.E. Allos ; S.R. Al-Araji ; E.H. Ezzet
  • Source: Radio and Electronic Engineer, Volume 51, Issue 9, p. 429 –434
  • DOI:  10.1049/ree.1981.0066
  • Type: Article
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  • p. 429 –434 (6)
    This paper defines a region of operation, calling it the pseudo-linear region, where a phase-locked loop (p.l.l.), behaves essentially in a linear manner. The results obtained for a loop with an active second-order filter suggest a very simple empirical definition for this region as a function of the parameters of the loop (ζ, and ωn), and classifies the regions of operation of the p.l.l., linear, pseudo-linear, non-linear and cycle slipping.
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Optimization of access points for automatic test program generation and fault location in large analogue circuits and systems
  • Author(s): M.A. Sarram ; J. Hywel Williams ; D.R. Towill ; K.C. Varghese
  • Source: Radio and Electronic Engineer, Volume 51, Issue 9, p. 435 –446
  • DOI:  10.1049/ree.1981.0067
  • Type: Article
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  • p. 435 –446 (12)
    The paper develops a methodology for the automatic test program generation (ATPG) for a large analogue circuit subject to component drifts. An optimization algorithm developed selects the best set of intermediate access points for a.c. and d.c. tests of the circuit.During ATPG, faults are simulated by varying each component over a wide range. Voltages measured at all available nodes are thus used in the pre-processing stage of node selection. An optimization procedure based on the discriminating power of measurements and separability between fault signatures is used to select the best set of frequencies applicable for all nodes in a.c. testing. A preamplifier and control amplifier of 56 components is chosen as Unit Under Test (UUT) to demonstrate the ATPG. The fault isolation scheme used is based on the nearest neighbour rule.The rexlationship between diagnosability and number of test features is shown to follow the customary Pareto type curve. However, four carefully chosen nodes and three carefully chosen test frequencies are shown to give an adequate level of diagnosability. The whole scheme is implemented automatically using a minicomputer interfaced to the UUT.
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Min m.i.s. schottky barrier solar cells—a review
  • Author(s): Y.W. Lam
  • Source: Radio and Electronic Engineer, Volume 51, Issue 9, p. 447 –454
  • DOI:  10.1049/ree.1981.0068
  • Type: Article
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  • p. 447 –454 (8)
    Problems inherent in conventional p-n junction solar cells are discussed. The principle of operation of min m.i.s. solar cells is then described. Among other advantages it is shown that the min m.i.s. solar cells are capable of giving a much higher Voc compared to the p-n junction solarcells. Problems associated with the min m.i.s. solar cells are also discussed. These include the incompatibility of light transmission and conductivity properties of the metal contact in the case of the contact covering the whole of the top surface, the contact linewidth/space ratio in the case of grating cells, resistivity dependence of Voc and degradation of cell performance in time.
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Detection processes for a 9600 bit/s modem
  • Author(s): A.P. Clark  and  M.J. Fairfield
  • Source: Radio and Electronic Engineer, Volume 51, Issue 9, p. 455 –465
  • DOI:  10.1049/ree.1981.0069
  • Type: Article
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  • p. 455 –465 (11)
    The paper describes various detection processes for a modem that has been designed for operation at 9600 bit/s over the public switched telephone network. The modem is a synchronous serial system, using a 16-point q.a.m. signal, with near-maximum-likelihood detection at the receiver. The detection processes are modifications of a technique that has recently been developed for use with severely distorted digital signals, the modifications leading to much simpler implementation. Results of computer simulation tests are presented, comparing the tolerances of the various detectors to additive white Gaussian noise, when the data are transmitted over different telephone circuits. The effects, on the tolerance to noise of a detector, of inaccuracies in the estimates of the level and carrier phase of the received signal are also studied.
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