• Title/Summary/Keyword: Early Minus Late Delay Lock Loop

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A Novel Code Tracking Scheme in Advanced Correlation Timing Offset Region for Band-Limited DS/SS System (좌부엽 상관간을 이용한 대역 제한된 직접수열 확산대역 시스템의 추적편이 완화 기법)

  • Yoo, Seung-Soo;Jung, Sang-Hyo;Yoon, Seok-Ho;Kim, Sun-Yong
    • Proceedings of the IEEK Conference
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    • 2007.07a
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    • pp.71-72
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    • 2007
  • 대역 제한된 DS/SS 시스템의 상관 함수는 최고 값이 나타나는 시점과 함께 이른 또는 늦은 상관시간 옵셋 영역에서 극소 또는 극대로 나타나는 시점을 특징점으로 갖는다. 이 가운데 이른 상관시간옵셋 영역의 상관 함수는 다중경로 신호에 의해 덜 왜곡되기 때문에 이 영역의 상관 함수를 이용해 부호 동기를 추적하여 유지할 수 있다면 EL-DLL (delay lock loop with early minus late discriminator) 보다 추적편이를 줄일 수 있다. 본 논문에 이런 특성을 이용하는 추적편이 완화 기법을 제안하고, 모의실험을 통해 성능을 알아본다.

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A Tracking Scheme using Correlation Value at Advanced Offset Range in Galileo BOC(1,1) Signal (Galileo BOC(1,1)에서 이른 상관시간 옵셋 영역의 상관 값을 이용한 추적기법)

  • Yoo, Seung-Soo;Kim, Sang-Hun;Yoon, Seok-Ho;Song, Iick-Ho;Kim, Jun-Tae;Kim, Sun-Yong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.1C
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    • pp.86-93
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    • 2008
  • The Galileo system, a global navigation satellite system(GNSS) developed by E.U., uses the direct sequence/spread spectrum(DS/SS) modulation. A DS/SS-based system performs a fine synchronization between the received and locally generated spreading signals, via attacking process. In the absence of multipath signals, using the symmetric characteristic of the correlation function, the delay lock loop with the early minus late discriminator(EL-DLL) offers the best performance in tracking. However, in the presence of multipath signals, the symmetry of the correlation function could be lost, causing a tracking bias. In this paper, we observe that the correlation values in the advanced offset range remain almost unchanged, due to the multipath signals being received later than a line-of-sight signal. Based on this observation, we propose a novel tracking scheme for a Galileo BOC(1,1) system.

A Novel Scheme for Code Tracking Bias Mitigation in Band-Limited Global Navigation Satellite Systems (위성 기반 측위 시스템에서의 부호 추적편이 완화 기법)

  • Yoo, Seung-Soo;Kim, Sang-Hun;Yoon, Seok-Ho;Song, Iich-Ho;Kim, Sun-Yong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.10C
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    • pp.1032-1041
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    • 2007
  • The global navigation satellite system (GNSS), which is the core technique for the location based service, adopts the direct sequence/spread spectrum (DS/SS) as its modulation method. The success of a DS/SS system depends on the synchronization between the received and locally generated pseudo noise (PN) signals. As a step in the synchronization process, the tacking scheme performs fine adjustment to bring the phase difference between the two PN signals to zero. The most widely used tracking scheme is the delay locked loop with early minus late discriminator (EL-DLL). In the ideal case, the EL-DLL is the best estimator among various DLL. However, in the band-limited multipath environment, the EL-DLL has tracking bias. In this paper, the timing offset range of correlation function is divided into advanced offset range (AOR) and delayed offset range (DOR) centering around the correct synchronization time point. The tracking bias results from the following two reasons: symmetry distortion between correlation values in AOR and DOR, and mismatch between the time point corresponding to the maximum correlation value and the synchronization time point. The former and latter are named as the type I and type II tracking bias, respectively. In this paper, when the receiver has finite bandwidth in the presence of multipath signals, it is shown that the type II tracking bias becomes a more dominant error factor than the type I tracking bias, and the correlation values in AOR are not almost changed. Exploiting these characteristics, we propose a novel tracking bias mitigation scheme and demonstrate that the tracking accuracy of the proposed scheme is higher than that of the conventional scheme, both in the presence and absence of noise.

A Combined Pseudo-random Noise Signal Based Advanced Region Correlation Scheme for BOC(pn,n) Modulated GNSS Signals in Repeat-back Jamming Environment (재방송 재밍 환경에서 BOC(pn,n) GNSS 변조된 신호를 위한 CP-ARC 기법)

  • Yoo, Seungsoo;Yeom, Dong-Jin;Jee, Gyu-In;Kim, Sun Yong
    • Journal of Institute of Control, Robotics and Systems
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    • v.22 no.11
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    • pp.977-983
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    • 2016
  • This paper proposes a novel code-tracking scheme to track the fine code synchronization for BOC (pn,n)-modulated global navigation satellite system signals in a repeat-back jamming environment. The correlation function of BOC (pn,n)-modulated signals has several peaks. The correlation function in the advanced offset region remains almost unchanged due to the repeat-back signals being received later than a line-of-sight signal in the same multipath signal receiving case. Additionally, the combined pseudo-random noise signal can be treated as repeat-back jamming signals, like multipath signals. In this paper, we propose a novel code-tracking scheme utilizing the advantages of using a combined pseudo-random noise signal in the advanced offset region and verify its performance through simulation.

A Generalized Advanced Region Correlation (G-ARC) Scheme for BOC(pn,n) Modulated Code Tracking in GNSS (BOC(pn,n) 변조된 확산신호의 부호동기추적을 위한 일반화된 이른영역상관기법)

  • Yoo, Seung-Soo;Lee, Young-Yoon;Kim, Yeong-Moon;Yoon, Seok-Ho;Kim, Sun-Yong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.3C
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    • pp.329-340
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    • 2009
  • This paper proposes a novel code tracking scheme to track the fine code synchronization for BOC(pn,n) modulated spreading signals. The correlation function of BOC(pn,n) modulated spreading signals has been several peaks. In this paper, we observe that the correlation function in the advanced offset region remains almost unchanged, due to the multipath signals being received later than a line-of-sight signal. Based on this observation, we propose a novel code tracking scheme which is called the advanced region correlation (ARC) method for BOC(n,n) modulated spreading signals. And, we compare with the code tracking accuracy between the conventional and proposed methods in the static multipath and land mobile satellite system channels through the Monte-Carlo simulation. Then, base on the proposed scheme, we propose the generalized-ARC (ARC) scheme for BOC(pn, n) modulated spreading signals.