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Vehicular Technology, IEEE Transactions on

Issue 3 • Date Aug. 1973

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Displaying Results 1 - 6 of 6
  • [Front cover and table of contents]

    Page(s): c1
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    Freely Available from IEEE
  • A mobile-radio space-diversity receiving system using delta modulation with a "STAR" type cophasing scheme

    Page(s): 61 - 68
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    A multiple branch predetection combining diversity receiver technique using pulse-envelope modulation of the transmitted signal is described. The receiver branches use the "STAR" scheme of multiple heterodyning of the received signal with itself to eliminate all exponential modulation components imparted by the transmission medium. Each branch can be shown to be mathematically equivalent to a simple square-law detector. A modulation scheme using low-bit-rate (50 kHz) companded delta modulation is proposed which provides a reasonable output signal-to-noise ratio (30-40 dB). The convenience of received signal gain control before pulse regeneration and the possible application of conjugate phase retransmission could make this technique useful. View full abstract»

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  • On the use of space diversity in the square-law reception of fading on-off keyed signals

    Page(s): 68 - 77
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    In this paper the total bit-error probability using square-law detection of an on-off keyed carrier received through a fading medium is calculated. It is shown that the use of diversity will recover much of the performance loss caused by the fading, provided that an optimum decision threshold is used. Consideration is given to the performance obtained with a fixed optimum threshold (depending only on the mean-square signal strength) and to that obtained with two forms of variable threshold, assumed to follow the instantaneous fading signal strength. Compared to the fixed optimum threshold, the best variable threshold results in a 5- or 2.5-dB reduction in the required rms SNR for a 10-4error rate with two- or four-branch diversity, respectively; as compared to the no fading case, use of the fixed threshold requires 3 dB more SNR for a 10-4error rate with four-branch diversity, and requires 32 dB more SNR if only a single branch is used. A calculation of the average fade duration of the diversity-combiner output-signal component shows that diversity reduces the average time that the signal component spends below the threshold according to N-1/2for N branches. This is true for both the fixed or the best variable threshold, but the average duration with the fixed threshold is larger by about [log (1+σρ2)]1/2, where σρ2is the mean-square SNR per branch. View full abstract»

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  • A UHF mobile telephone system using digital modulation: Preliminary study

    Page(s): 78 - 81
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    A UHF mobile telephone system using digital modulation is described. The system uses on-off keying of an 836-MHz carrier, the code being supplied by an adaptive delta coder with a clock frequency of 50 kHz. The maximum audio baseband signal-to-noise ratio is approximately 30 dB. The mobile receiver employs space diversity in a maximal-ratio combiner. Due to the use of amplitude modulation of the carrier rather than exponential modulation, the diversity receiver is very simple. The system was tested in the laboratory and in the field. Field tests were made in suburban and urban areas. For the four-branch system, threshold occurred at an average IF signal-to-noise ratio of approximately 12 dB. View full abstract»

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  • The effect of background noise on phase ranging measurements in urban vehicle monitoring systems

    Page(s): 81 - 85
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    The effect of background noise on the performance of phase-trilateration urban vehicle-monitoring systems is discussed. An expression for the density function of the error as a function of such system parameters as carrier-to-noise ratio, frequency deviation, observation time, and bandwidth is derived. View full abstract»

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  • [Back cover]

    Page(s): c4
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    Freely Available from IEEE

Aims & Scope

IEEE Transactions on Vehicular Technology covers land, airborne, and maritime mobile services, vehicular electrotechnology, equipment, and systems identified with the automotive industry.

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Meet Our Editors

Editor-in-Chief
Yuguang Michael Fang
University of Florida