• Title/Summary/Keyword: Range Correlation Effect

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A Study on the Forward- and Reverse-Link Interrogation Range of a UHF RFID System (UHF RFID 시스템의 순방향 및 역방향 인식 거리에 관한 연구)

  • Jang, Byung-Jun;Park, Jun-Seok;Cho, Hong-Gu;Lim, Jae-Bong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.11
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    • pp.1243-1253
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    • 2007
  • Recently UHF RFID system has drawn a great deal of attention because of its potential to revolutionize supply chain management. An important characterization of the performance of a RFID system is 'interrogation range', which is defined as the maximum distance between a reader and a tag. Forward-link interrogation range is defined as the maximum distance from which the tag receives just enough power to turn on and back-scatter, and reverse-tink interrogation range is the maximum distance from which the reader can detect this back-scattered signal. A link balance has to be found between the two interrogation ranges. In this paper, the interrogation range equations are formulated in both forward-link and reverse-link and a trade-off between the two values is investigated in order to maximize the interrogation range. As a result, it is observed that the gain of the reader antenna, the isolation of the circulator, and the phase noise of the local oscillator with range correlation effect mainly determine the reverse-link interrogation range.

Performance Analysis of the UHF RFID Reader with the Range Correlation Effects of the Phase Noise (위상 잡음의 거리 상관 효과에 따른 UHF RFID 리더의 성능 분석)

  • Jang, Byung-Jun;Kang, Min-Soo;Lim, Jae-Bong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.2
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    • pp.152-160
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    • 2008
  • In this paper, we analyze the performance of a direct-conversion UHF RFID reader with the range correlation effects of the phase noise. Since a UHF RFIB system uses the same oscillator to generate the transmitted carrier and the local oscillation, the periodic interference and phase noise reduction effects occur due to time delay between two signals. Through exact theory and simulation, we verify how to cancel the periodic interference phenomena using I/Q diversity combining technique. And, we analyze phase noise reduction effects due to range correlation as a function of the tag-reader distance and the offset frequency Using these results, we simulate the symbol-error-rate performance with respect to phase noise with and without range correation effects. We show that the phase noise of the local oscillator has little effect on the symbol-error-rate performance because of phase noise reduction by range correlation.

Noise Analysis and Measurement for a CW Bio-Radar System for Non-Contact Measurement of Heart and Respiration Rate (호흡 및 심박수 측정을 위한 비접촉 방식의 CW 바이오 레이더 시스템의 잡음 분석 및 측정)

  • Jang, Byung-Jun;Yook, Jong-Gwan;Na, Won;Lee, Moon-Que
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.9
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    • pp.1010-1019
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    • 2008
  • In this paper, we present a noise analysis and measurement results of a bio-radar system that can detect human heartbeat and respiration signals. The noise analysis including various phase noise effects is very important in designing the bio-radar system, since the frequency difference between the received signal and local oscillator is very small and the received power is very low. All of the noise components in a bio-radar system are considered from the point of view of SNR. From this analysis, it can be concluded that the phase noise due to antenna leakage is a dominant factor and is a function of range correlation. Therefore, the phase noise component with range correlation effect, which is the most important noise contribution, is measured using the measurement setup and compared with the calculated results. From the measurement results, our measurement setup can measure a closed-in phase noise of a free-running oscillator. Based on these results, it is possible to design a 2.4 GHz bio-radar system quantitatively which has a detection range of 50 cm and low power of 1 mW without additional PLL circuits.