• 한국통신학회논문지
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• 제30권10C호
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• pp.992-998
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• 2005

본 논문에서는 고정밀 차량위치 추적 기반의 교통신호등 제어를 위한 저전송율 초광대역 무선통신 시스템에서의 Ultra Fast Acquisition 알고리즘을 연구하였다. 현재 CDMA에서 사용되는 acquisition방식으로는 저전송율 UWB시스템에서 회로가 복잡해지고 빠른 acquisition을 기대할 수 없기 때문에 새로운 Ultra Fast Acquisition방식이 필요하다. 기본적으로 Sequential Estimation방식을 사용하며 trinomial m-시퀀스를 사용하여 유비쿼터스 센서 네트워크용 U시스템에서 long PN code를 사용하는 경우에도 회로의 복잡도를 줄이고 FCC Emission limit을 만족시키면서, $1\~3{\mu}sec$이내의 acquisition을 가능하도록 설계하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(5)
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• pp.85-88
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• 2000

This paper describes a Band-Selective Charge-Pump PLL(CPPLL) for clock recovery and clock generator. The proposed PLL satisfies fast acquisition time and low jitter characteristics simultaneously by reducing initial frequency error. The acquisition time of the designed Band-Selective CPPLL can be decreased down to 55% of a conventional CPPLL.

• Journal of information and communication convergence engineering
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• 제9권3호
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• pp.305-309
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• 2011

This paper proposes a new rotational frequency detector (RFD) for phase-locked loop (PLL) or clock and data recovery (CDR) applications for fast frequency acquisition. The proposed RFD uses the four states finite state machine (FSM) model to accelerate the frequency acquisition time. It is modeled and simulated with MATLAB Simulink. The functionalities of the proposed RFD are examined and the results are compared to those of a conventional RFD. The proposed RFD's frequency acquisition time is four times faster than that of a conventional one. The proposed RFD incorporated with a phase detector (PD) in PLL or CDR is expected to improve the frequency and phase acquisition performance later greatly.

• 제어로봇시스템학회논문지
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• 제14권6호
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• pp.603-607
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• 2008

This paper proposes a fast acquisition method using INS velocity and multiple correlators for high speed vehicles. In order to reduce acquisition time in GPS receiver, the method utilizes inertial velocity information and multiple correlators. Search range of the Doppler frequency is reduced by using INS velocity and the number of cells at one search can be increased by using multiple correlators. By using both multiple correlators and the INS velocity in the acquisition, search space can be greatly reduced. Experimental results show that the method gives faster signal acquisition performance than the conventional method.

• Journal of Positioning, Navigation, and Timing
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• 제11권1호
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• pp.11-21
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• 2022

Fast Fourier transform (FFT)-based parallel acquisition techniques with reduced computational complexity have been widely used for the acquisition of binary phase shift keying (BPSK) global positioning system (GPS) signals. In this paper, we propose a low computational FFT-based fine acquisition technique, for binary offset carrier (BOC) modulated BPSK signals, that depending on the subcarrier-to-code chip rate ratio (SCR) selectively utilizes the computationally efficient frequency-domain realization of the BPSK-like technique and two-dimensional compressed correlator (BOC-TDCC) technique in the first stage in order to achieve a fast coarse acquisition and accomplishes a fine acquisition in the second stage. It is analyzed and demonstrated that the proposed technique requires much smaller mean fine acquisition computation (MFAC) than the conventional FFT-based BOC acquisition techniques. The proposed technique is one of the first techniques that achieves a fast FFT-based fine acquisition of BOC signals with a slight loss of detection probability. Therefore, the proposed technique is beneficial for the receivers to make a quick position fix when there are plenty of strong (i.e., line-of-sight) GNSS satellites to be searched.

• 한국통신학회논문지
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• 제21권3호
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• pp.684-691
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• 1996

Since the period of a spreading code in DS/SS communication systems is generally long, it is necessary to make the code acquisition as fast as possible. The code acquisition time can be sued as a measure to evaluate the performance of code acquisition systems. The search rate of serial search codee acquisition system used in the coventional CDMA cellular system is lower than that of the matched filter technique. In order to reduce the code acquisition time, this paper proposes hybrid code acquisition system composed filters combined with serial search blocks. In the proposed system, the matched filter sweeps possible code phases fast and the acquired phase information is verified by the serial search block. The mean and the variance of its acquisition time are calculated and compared with those of double dwell serial search system. The results indicate better performance of the proposed system by yielding its small vaues of the mean and the variance of code acquisition time.

• 한국통신학회논문지
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• 제29권8A호
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• pp.898-908
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• 2004

본 논문에서는 RACH(Random Access Channel) 구조에 적자한 WCDMA 역방향 링크 수신기용 고속 프리앰블 탐색기를 제안한다. WCDMA 시스템에서는 IS-95 시스템과 상이한 AISMA(Acquisition Indication Sense Multiple Access)방식을 적용하고 있으므로 UE에서 송신하는 RACH 프리앰블과 수신하는 AI(Acquisition indicators)의 시간 제한이 존재하며, 또한 RACH에 할당된 시그너쳐의 수가 제한적이므로 원활한 동작을 위하여 RACH 프리앰블에 대한 빠른 포착 확인이 요구된다. 본 논문에서 제안하는 프리앰블 탐색자는 2 안테나 기반의 구조로 빠른 포착(acquisition)을 위하여 radix-2 16 point FFT구조를 갖는 FHT(Fast Hadamard Transform)를 적용하였다. 본 논문의 FHT는 각 시그너쳐를 상관하는 일반적인 방식보다 최대 32배의 빠른 포착이 가능하다. 이러한 빠른 포착 능력을 기반으로 전체 프리앰블 4096칩에 대한 상관을 수행함으로써 포착 성능을 극대화하였다. 본 논문에서 제안한 프리앰블 탐색기는 WCDMA 기지국 모뎀 구현에 적용되었으며, 성능 분석은 Neyman-pearson 방식을 이용하였다.

• ETRI Journal
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• 제32권1호
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• pp.142-144
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• 2010

In this letter, we propose GPS L5 acquisition schemes to detect a fast code phase and improve the accuracy of the Doppler frequency. The proposed approach is based on the code-phase changes which occur during the acquisition processing time originating in the Doppler frequency. The proposed schemes detect a fast code phase within about 1 chip near the estimated code phase and improve the accuracy of the Doppler frequency by up to about 4 times in comparison with the popular Septentrio receiver. The feasibility of the proposed schemes is demonstrated through simulation.

• 제어로봇시스템학회논문지
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• 제12권8호
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• pp.765-772
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• 2006

The L2 Civil Signal (L2CS) will be transmitted by modernized IIR(IIR-M), IIF and all subsequent GPS satellites. It contains two codes of different length; CM code contains 10,230chips, repeats every 20milliseconds and is modulated with message data, and CL code contains 767,250chips, repeats every 1.5second Z-count and has no data modulation. And the message data is encoded for Forward Error Correction(FEC). The long code length is useful for weak signal, but it also requires very long acquisition time. Therefore, the structure of GPS Ll/L2C Correlator and the fast acquisition scheme are proposed in this paper.

• Journal of Positioning, Navigation, and Timing
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• 제4권4호
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• pp.151-160
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• 2015

GPS L2C signal is a recently added civil signal to L2 frequency and is constructed by time division multiplexing of civil moderate (L2-CM) and civil long (L2-CL) code signals. While the L2-CM code is 20 ms-periodic and modulates satellite navigation message, the L2-CL code is 1.5s-periodic with 767,250 chips long code sequence and carries no data. Therefore, the L2-CL code signal allows receivers to perform a very long coherent integration. However, due to the length of the L2-CL code, the acquisition of the L2-CL code signal may take too long or require too much hardware resources. In this paper, we propose a three-step ultra-fast L2-CL code acquisition (TSCLA) technique for dual band GPS receivers. In the proposed TSCLA technique, a dual band GPS receiver sequentially acquires the coarse/acquisition (C/A) code signal at L1 frequency, the L2-CM code signal, and the L2-CL code signal to minimize mean acquisition time (MAT). The theoretical performance analysis and numerous Monte Carlo simulations show the significant advantage of the proposed TSCLA technique over conventional techniques introduced in the literature.