2004/2

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Recent Submissions

Now showing 1 - 5 of 8
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    On the High Altitude Platform (HAP) W-CDMA System Capacity
    (Společnost pro radioelektronické inženýrství, 2004-06) Taha-Ahmed, Bazil; Calvo-Ramon, Miguel; de Haro-Ariet, Leandro
    The performance of a downlink power control model, based on a n-th power distance law, is evaluated for high altitude platform station (HAPS) W-CDMA systems. The downlink capacity using this model is compared with the uplink capacity. It is shown that the uplink capacity is higher than the downlink capacity.
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    Asymptotic Analysis of Optimal Piecewise Uniform Polar Quantization
    (Společnost pro radioelektronické inženýrství, 2004-06) Peric, Zoran H.; Bogosavljevic, Srdjan M.
    In this paper, a simple and complete asymptotical analysis is given for a mean square error (MSE) piecewise uniform polar quantizer (PUPQ). We show that PUPQ has the same performance as the asymptotic nonuniform polar quantizer (NPQ) and has implementation complexity between complexities of NPQ and uniform polar quantization. The goal of this paper is solving the quantization problem in case of PUPQ and finding the corresponding support region.
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    Frequency Stability Improvement in Direct Digital Frequency Synthesis
    (Společnost pro radioelektronické inženýrství, 2004-06) Stofanik, Vladimr; Balaz, Igor
    The paper describes a digital frequency synthesizer that incorporates a novel method of the clock signal frequency versus temperature dependency compensation. The clock signal is derived directly from a dual mode crystal oscillator (DMXO). With introducing the method, synthesized signal frequency versus temperature instability below a0.15ppm can be obtained over a wide temperature range (between 45°C and +85°C). Since a temperature information is obtained directly from a crystal itself rather than from an external sensor, temperature offset and lag effects are eliminated.
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    Rain Intensity Statistical Processing and Comparison with ITU-R Recommendations
    (Společnost pro radioelektronické inženýrství, 2004-06) Kvicera, Vaclav; Grabner, Martin; Hlavaty, Michal
    Rain intensities have been measured since February 1992 by means of a heated siphon raingauge. Rain intensity data gathered over 11-year period were statistically processed, cumulative distributions of rain intensities obtained, and relations between them were compared with ITU-R recommendations.
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    S-Parameter Measurements in the Time Domain
    (Společnost pro radioelektronické inženýrství, 2004-06) Tkadlec, Roman
    The paper provides a basic overview of the theory of time-domain measurements. Results of the use time-domain techniques to obtain S-parameter are here presented. Advantages and disadvantages of this technique compared to frequency-domain measurements are mentioned.