• Journal of Positioning, Navigation, and Timing
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• v.4 no.3
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• pp.107-114
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• 2015

Binary Offset Carrier (BOC) signal planned for future Global Navigation Satellite System (GNSS) provided better positioning accuracy and smaller multipath error than GPS C/A signal. However, due to the multiple side peaks in the auto-correlation function (ACF) of the BOC modulated signals, a receiver may false lock onto one of the side peaks in the tracking mode. This false lock would then result in a fatal tracking error. In this paper, we propose an unambiguous tracking method for composite BOC (CBOC) signals to mitigate this problem. It aims to reduce the side peaks of the ACF of CBOC modulated signals. It is based on the combination of traditional CBOC correlation function (CF) and reference CF of unmodulated pseudo- random noise code (PRN code). First, we present that cross-correlation function (CCF) with unmodulated PRN code is close to the secondary peaks of the traditional CBOC. Then, we obtain an unambiguous correlation function by subtracting traditional CBOC ACF from these CFs. Finally, the tracking performance for the CBOC signals is examined, and it is shown that the proposed method has better performance than the traditional unambiguous tracking method in additive white Gaussian noise (AWGN) channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.6
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• pp.512-519
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• 2013

In this paper, we propose a novel unambiguous correlation function for composite binary offset carrier (CBOC) signal tracking. First, we observe that a sub-carrier of CBOC signal is seen as a sum of four partial sub-carriers, and generate four partial-correlations composing the CBOC autocorrelation. Then, we obtain an unambiguous correlation function with a sharp main-peak by re-combining the partial correlations. From numerical results, we confirm that the proposed unambiguous correlation function offers a better tracking performance than the conventional correlation functions in terms of the tracking error standard deviation and multipath error envelope.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1433-1440
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• 2015

In this paper, we propose an unambiguous correlation function to improve tracking performance for binary offset carrier (BOC) signals. Specifically, we divide a BOC sub-carrier into multiple rectangular pulses, and analyze that the BOC autocorrelation function is made up of the sum of several partial correlation functions. Then, we obtain two sub-correlation functions by combining two partial correlation functions and propose a novel unambiguous correlation function with no side-peak which can be regulated its width based on the combination of the sub-correlation functions and partial correlation functions. From numerical results, it is confirmed that the proposed correlation function provides a tracking performance improvement over the conventional correlation functions in terms of the tracking error standard deviation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.6
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• pp.343-349
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• 2014

In this paper, we propose a three-stage unambiguous tracking scheme for CBOC signals. We evenly divide composite binary offset carrier (CBOC) signal, which was adopted in the Galileo system developed by the European Union (EU), by width of BOC(6,1) signal pulse, and then, generate 12 partial correlations. Then, we generate an unambiguous correlation function by recombining the partial correlations with two kinds of operation. The proposed correlation function is narrower and higher than the conventional correlation functions. From simulation result, it is shown that the proposed correlation function offers a better signal tracking performance over the conventional correlation functions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9C
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• pp.581-588
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• 2011

In this paper, we propose a novel unambiguous code tracking scheme for cosine phased binary offset carrier (BOC) signals. We first obtain the sub-correlation functions composing the BOC autocorrelation function, and then, re-combine the sub-correlation functions generating a correlation function with no side-peak. Finally, by using the correlation function with no side-peak in the delay lock loop, the proposed scheme performs unambiguous signal tracking. Numerical results demonstrate that the proposed scheme provides a performance improvement over the conventional unambiguous scheme in terms of the tracking error standard deviation (TESD).

• MALSORI
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• no.51
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• pp.57-69
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• 2004

Comprehension monitoring is a process of message evaluation and a very important skill of communication. Comprehension monitoring is a necessary language skill in classroom, as it is important for children to assess their own understanding of task instructions and teaching content. The present study investigated comprehension monitoring skill of children with Specific Language Impairment(SLI) compared to age-matched children and language-matched children. 18 vignettes and 6 displays were constructed. Children were asked to choose one object or 'DK' card from a display after the children listened to the vignettes. The results showed that children with SLI didn't have problem in comprehending unambiguous utterance and using prior statement. However, they had problem in monitoring comprehending ambiguous utterance compared age-matched children. Their performance were similar to language matched younger children. With respect to their performance, several possible explanations were discussed.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.3
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• pp.45-55
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• 2002

중거리 유도무기 체계가 탄도탄과 같이 기동이 심한 표적과 교전할 때에는 지상 레이더는 표적 및 유도탄 위치정보를 보다 빈번하게 전송하여야 하지만, 자신의 임무를 수행해야 하므로 유도탄 및 교전 표적에 대한 정보를 필요이상으로 자주 전송할 수 없다. 이러한 상황에서 탐색기가 자체적으로 표적의 거리, 속도, 방향을 측정함으로서 지상레이더에 추가 부담을 지우지 않고 우수한 추적 정밀도로 교전성능을 향상할 시킬 수 있는 고반복 펄스열을 사용하는 PRF 변조방식을 제안한다.

• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2717-2720
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• 2010

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.957-963
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• 2015

The autocorrelation of an alternative binary offset carrier (AltBOC) signal provides an improved positioning accuracy because of its narrow main-peak. However, The AltBOC signal has a disadvantage that the autocorrelation of the AltBOC signal has multiple side-peaks which incur a severe positioning error. In this paper, we propose a generating method of an unambiguous correlation function for AltBOC signal tracking. Specifically, we first obtain symmetric partial correlation functions, and subsequently, we obtain an unambiguous correlation function by combining them. In numerical results, it is confirmed that the proposed correlation function provides better tracking error standard devation (TESD) performances comparing with the conventional correlation functions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.7
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• pp.559-565
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• 2014

In this paper, we propose an unambiguous correlation function for time-multiplexed binary offset carrier (TMBOC) signal tracking. Specifically, considering that the TMBOC modulation transmits two kinds of sine-phased BOC signals in time domain alternatively, we generate sub-correlation functions for each of the BOC signals by using split sine-phased BOC signals, and then, obtain a correlation function with no side-peak by recombining the sub-correlation functions. From numerical results, we confirm that the proposed correlation function offers an improved tracking error standard deviation performance than the TMBOC autocorrelation function.