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Radio and Electronic Engineer

Issue 3 • Date March 1971

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Displaying Results 1 - 7 of 7
  • Manpower in the electronics industry

    Publication Year: 1971
    Save to Project icon | PDF file iconPDF (138 KB)  
    Freely Available from IEEE
  • Notices

    Publication Year: 1971
    Save to Project icon | PDF file iconPDF (153 KB)  
    Freely Available from IEEE
  • Speech scrambling by the re-ordering of amplitude samples

    Publication Year: 1971
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (5635 KB)  

    Many modern communication systems transmit amplitude samples of the original input signal, the sampling being carried out according to the wellknown requirements of the Sampling Theorem. At the receiver the signal is reconstituted by low-pass filtering. This paper investigates the degree of privacy which can be introduced in a speech communication system by deliberate variation of the order of transmission of the samples. The distortion of the signal which results from the low-pass filtering of such 'scrambled' samples is investigated theoretically and practically, and intelligibility tests are used to assess the effectiveness of the system. Finally, some guidance is given as to the selection of the scramble sequence for maximum effectiveness. View full abstract»

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  • Measurement techniques in television studios and outside broadcasts

    Publication Year: 1971 , Page(s): 113 - 125
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2538 KB)  

    A review is given of some methods of measurement employed in colour television studios and outside broadcasts which are used for acceptance tests which are carried out when new equipment is commissioned. Line-up of major items of apparatus, and the assessment of performance of temporary line or radio link transmission circuits, are also considered. View full abstract»

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  • Relationship between F.M. noise and current noise in a cavity-controlled gunn effect oscillator

    Publication Year: 1971 , Page(s): 126 - 132
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (846 KB)  

    A theory is developed to account for the observed ratio of f.m. noise and current noise in a cavity-controlled Gunn effect oscillator. The noise processes are assumed to have their origin in spontaneous fluctuations in the carrier concentration of the GaAs layer which give rise to a modulation of the Gunn diode impedance. The principal parameters of interest in the study are device current and domain capacitance both of which are functions of the carrier concentration n and the internal field F of the GaAs layer. In order to estimate the relative contribution of the two terms in the expression derived for fluctuation in the device an analysis is made of the fluctuation mechanisms in terms of the zero-diffusion model of a propagating domain. It is concluded that the term representing the effect of internal field fluctuations makes only a minor contribution to the f.m. noise and current noise. Experimental evidence is produced in support of the theoretical study and an estimate is made of the carrier concentration fluctuation. View full abstract»

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  • Avalanche diodes as transfer noise standards for microwave radiometers

    Publication Year: 1971 , Page(s): 133 - 136
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (519 KB)  

    Transfer calibrations of radiometers are performed by injecting noise via a directional coupler. The avalanche diode appears to have all of the physical attributes of the plasma noise tube, except for a reasonably predictable absolute noise level. Its saving in space, weight, cost and power consumption render it an attractive proposition for transfer noise calibrations. Results of measurements at three frequencies between 1 GHz and 3 GHz are given. View full abstract»

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  • Automatic measurement of insertion test signals

    Publication Year: 1971 , Page(s): 137 - 143
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (861 KB)  

    This paper describes some of the problems and constraints associated with the measurement of insertion test signals and outlines various techniques which are either being used or under investigation for the automatic measurement of the various elements in the signals. View full abstract»

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