• 대한전자공학회논문지
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• 제24권1호
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• pp.1-9
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• 1987

In this paper, the acquisition performance of a receiver that utilizes a non-coherent digital correlator is analyzed. In order to analyze the acquisition performance, the probability density function of a receiver output random variable has been derived approximately. Using this function, the acquisition performance of the coarse acquisition code receiver in a global positioning system is analyzed.

• Journal of Positioning, Navigation, and Timing
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• 제4권3호
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• pp.97-105
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• 2015

A navigation signal based on orthogonal tiered polyphase code was proposed. For the proposed signal, tiered polyphase code was used as the code of a pilot channel. Tiered polyphase code is a complex number type code, and thus the pilot channel and data channel were separated using the Walsh code which makes the correlation between different codes become 0. The results of the simulation indicated that the correlation characteristics and signal acquisition performance of the proposed signal were identical to those of tiered polyphase code, and that the disadvantage of tiered polyphase code could be supplemented through a data channel in terms of signal tracking.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.285-288
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• 2005

In this paper, we propose a two step Binary Exponential search algorithm for rapid acquisition time of UWB(Ultra Wide Band) signal on UWB communication systems. Previous proposed timing acquisition algorithm is searching whole frame that consist of the number of n Bins to terminate search, however this paper proposed two step Binary Exponential search algorithm can achieve remarkable reduction of UWB signal acquisition time as limiting search group. Proposed search algorithm is consisting of search group establishment step and Bit Reversing of search group establishment step.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.33.6-33
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• 2002

For RF sensitivity enhancement, the previous assisted GPS acquisition architecture adopts not only the coherent integration technique but also the non-coherent integration technique since the long coherent integration time increases the number of the frequency search cells. But the non-coherent integration technique induces the squaring loss, which is the dominant factor among the acquisition losses of assisted GPS dealing with weak GPS signals. This paper proposes an efficient architecture for weak signal acquisition in assisted GPS. In this paper, it is explained that the proposed architecture reduces the squaring loss using a modified non-coherent integration technique. Furthermore, it is..

• 대한전자공학회논문지
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• 제21권6호
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• pp.105-114
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• 1984

본 논문에서는 direct sequence(DS) 방식을 이용한 spread spectrum system에 사용할 수 있는 빠른 초기 동기 방법을 제안하였다. 수식적인 모델을 세우고 해석을 한 후 computer simulation을 거쳐 제안된 system의 성능을 분석하여 sliding correlator에 비해 우수함을 입증하였다. 입력 신호의 signal-to-noise ratio(SNR)가 -18dB에서 초기 동기 시간이 45ms 소요되었다. 이 방법의 hardsware 구현과 실험 결과도 설명하였다.

• 센서학회지
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• 제29권3호
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• pp.162-171
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• 2020

The incidences of cardiovascular diseases are rapidly increasing worldwide. The electrocardiogram (ECG) is a test to detect and monitor heart issues via electric signals in the heart. Presently, detecting heart disease in real time is not only possible but also easy using the myDAQ data acquisition device and LabVIEW. Hence, this paper proposes a system that can acquire ECG signals in real time, as well as detect heart abnormalities, and through light-emitting diodes (LEDs) it can simultaneously reveal whether a particular waveform is in range or otherwise. The main hardware components used in the system are the myDAQ device, Vernier adapter, and ECG sensor, which are connected to ECG monitoring electrodes for data acquisition from the human body, while further processing is accomplished using the LabVIEW software. In the Results section, the proposed system is compared with some other studies based on the features detected. This system is tested on 10 randomly selected people, and the results are presented in the Simulation Results section.

• 한국통신학회논문지
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• 제33권6A호
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• pp.685-692
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• 2008

본 논문에서는 Inmarsat (International Marine Satellite) mini-m 시스템의 하향 링크 수신기를 위한 timing recovery 루프를 제안한다. Inmarsat mini-m 시스템 규격에서 요구하는 frequency tolerance는 ${\pm}924$ Hz (signal bandwidth: 2.4 kHz) 이며, timing acquisition 시간은 하나의 UW (Unique Word) 신호 구간인 15ms 이기 때문에 주파수 옵셋에 강인하고 UW 신호 구간에서의 빠른 aquisition 이 가능한 루프 설계가 요구된다. 이에 따라 본 논문에서는 주파수 옵셋에 강인하고 빠른 aquisition 이 가능한 timing recovery 루프를 제안하였으며, 제안된 timing recovery 루프는 UW detector와 UW detector에 의해 검출된 UW 신호를 이용한 timing recovery 루프를 연동한 구조이다. UW detector는 주파수 옵셋 환경에서 안정적인 성능을 위해 차동 기반의 noncoherent detector 방식을 적용하였으며, TED (Timing Error Detector) 알고리즘은 기존의 GAD (Gardner Detector) 알고리즘 대신 본 논문에서 제안하는 UW 신호를 이용한 차동 기반의 ELD (Early Late Detector) 알고리즘 적용하였다. 제안된 방식과 기존의 GAD와의 성능 비교를 통해 제안된 방식이 만족스러운 성능과 신뢰성 있는 동작이 가능함을 입증하였다.

• Journal of Positioning, Navigation, and Timing
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• 제4권4호
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• pp.161-171
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• 2015

Alternative binary offset carrier (AltBOC) signals can be approximated by four synchronized direct sequence spread spectrum (DSSS) signals, each pair of which is a quadrature phase shift keyed (QPSK) signal at a different frequency. Therefore, depending on the strength of an incoming AltBOC signal, an acquisition technique can reduce the mean acquisition time (MAT) by searching the four DSSS signals asynchronously; the search for each of the four DSSS signals can start at one of the evenly separated hypotheses on the two-dimensional hypothesis space. And detection sensitivity can be improved by multiple levels when different numbers of search results for the same hypothesis are combined. In this paper, we propose a fast AltBOC acquisition technique that has an asynchronous search strategy and efficiently utilizes the output of the four search results to increase the sensitivity level when sensitivity improvement is needed. We provide a complete theoretical analysis and demonstrate with numerous Monte Carlo simulations that the MAT of the proposed technique is much smaller than conventional AltBOC acquisition techniques.

• 한국통신학회논문지
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• 제36권7C호
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• pp.459-466
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• 2011

본 논문에서는 위성항법 시스템에서 (global navigation satellite system: GNSS) 사용되는 이진 옵셋 반송파(binary offset carrier: BOC) 신호 상관함수의 주변 첨두 때문에 발생하는 신호 획득 문제에 대해 소개한다. 우선 BOC 신호의 상관함수를 분석하여 상관함수의 주변 첨두가 불규칙한 형태를 갖는 부 상관함수들의 결합을 통해 형성된다는 점을 관찰하며, 관찰 결과를 바탕으로 cyclostationarity를 지니는 부 상관함수들의 재조합에 기반을 둔 신호 획득 기법을 제안한다. 제안한 기법은 모든 BOC 신호에 적용되어 주변 첨두를 완벽히 제거할 수 있으며, 모의실험을 통해 제안한 기법이 기존의 기법들에 비해 더 나은 평균 신호 획득 시간 (mean acquisition time: MAT) 성능을 제공함을 보인다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1994년도 춘계학술대회
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• pp.53-56
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• 1994

We have developed biological signal measurement modules and data acquisition and control card for a biological signal measurement, archiving, and communication system (SiMACS). Biological signals included in this system are ECG, EEG, EMG, invasive blood pressure, respiration, and temperature. Parameters of each module can be controlled by PC-base IDPU (intelligent data processing unit) through a data acquisition and control card. The data acquisition and control card can collect up to 16 channels of biological signals with sampling rate of $50\;{\sim}\;2,000Hz$ and 12-bit resolution. All measurement moduls and data acquisition functions are controlled by microcontroller which receives commands from PC. All data transfers among PC, microcontroller, and ADC are done through a shared RAM access by polling method for real rime operation.