• 제어로봇시스템학회논문지
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• 제20권10호
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• pp.1073-1078
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• 2014

In this paper, an effective repeat-back jamming (RBJ) mitigation scheme known assuccessive repeat-back jamming cancellation (SRC) is proposed for the utilization of the successive interference cancellation (SIC) algorithm which is used to mitigate the near-far effect and the multiple-access interference for code division multiple-access communication systems. The proposed scheme uses a combined pseudo-random noise (C-PRN) signal from the estimated major parameters of RBJ signals. To evaluate the performance of the proposed scheme, the root mean squared (RMS) code tracking errors are shown according to the standard deviation of the parameter estimation errors of an RBJ signal, and using the well-known major parameters estimation schemes with a C-PRN signal through Monte-Carlo simulation.

• 제어로봇시스템학회논문지
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• 제20권9호
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• pp.977-983
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• 2014

A repeat-back jamming signal is an intentionally re-broadcasted GNSS (Global Navigation Satellite System) interference. In this paper, a novel repeat-back jamming detection scheme is proposed. The proposed scheme uses a combined pseudo random noise signal (C-PRN) and is available for a generic GNSS receiver with a single antenna. The C-PRN signal is made by combining several received pseudo random noise signals that had been transmitted from the visible GNSS satellites. Through a Monte-Carlo simulation, the detection probability of a repeat-back jamming signal detected with the proposed scheme is presented.

• 제어로봇시스템학회논문지
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• 제22권8호
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• pp.665-670
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• 2016

This paper proposes a repeat-back jamming signal detection scheme using a correlation ratio test metric of a combined pseudo-random noise signal for global navigation satellite systems. The correlation ratio test metric allows for the monitoring of possible distortions in the signal correlation. The proposed scheme is a modified version of the correlation ratio test metric to detect a repeat-back jamming signal in a multipath environment. Through a Monte-Carlo simulation, it is confirmed that the proposed scheme detects almost the whole case, which is received a repeat-back jamming signal under the 6 dB jamming to signal power ratio.

• 한국항행학회논문지
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• 제17권2호
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• pp.157-164
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• 2013

일반적으로 기만신호는 GPS 신호보다 세기가 강한 신호이기 때문에 기만신호가 가해졌을 경우 GPS 신호의 정보를 획득하기는 어렵다. 특정 위성에 대한 기만신호가 발생하면 위성신호 획득시 도플러 주파수와 코드 페이스의 2차원 공간에 두 개의 피크가 존재하게 된다. 이를 이용하여 기만신호 존재 여부를 판단하고 각각의 신호획득 결과에 대한 채널 정보를 바탕으로 신호추적과정을 수행하여 기만신호를 제외한 GPS 신호를 활용할 수 있다. 본 논문에서는 의사위성 시뮬레이터를 이용하여 현재 가시위성 중 하나의 PRN에 대한 기만신호를 생성한 다음 소프트웨어 수신기를 이용하여 두 번의 신호획득 과정을 수행하여 두 개의 피크를 검출하고 각각에 대한 신호추적 이후 정상적인 GPS 신호의 결과를 추출할 수 있음을 확인하였다.

• Journal of Positioning, Navigation, and Timing
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• 제2권1호
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• pp.1-8
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• 2013

A signal system for improving the code acquisition complexity of Global Navigation Satellite System (GNSS) receiver is proposed and the receiving correlator scheme is presented accordingly. The proposed signal system is a hierarchical code type with a duplexing configuration which consists of the Zadoff-Chu (ZC) code having a good auto-correlation characteristic and the Pseudo Random Noise (PRN) code for distinguishing satellites. The receiving correlator has the scheme that consists of the primary correlator for the ZC code and the secondary correlator which uses the PRN code for the primary correlation results. The simulation results of code acquisition using the receiving correlator of the proposed signal system show that the proposed signal scheme improves the complexity of GNSS receiver and has the code acquisition performance comparable to the existing GNSS signal system using Coarse/Acquisition (C/A) code.

• Journal of Positioning, Navigation, and Timing
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• 제4권3호
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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.

• Clinical and Experimental Vaccine Research
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• 제13권3호
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• pp.242-252
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• 2024

Purpose: In this study, an in-house enzyme-linked immunosorbent assay (ELISA) was developed and validated. The titer of ELISA was calculated using the reference line (RFL) method based on the standard curve drawn using the international reference anti-mouse serum NIBSC (National Institute for Biological Standards and Control) 97/642. Materials and Methods: In the development step, signal to noise was depicted to select the buffers that showed the most appropriate ratio. In the validation step, standard range, precision, dilution linearity, and specificity were confirmed, and RFL and parallel line (PLL) methods were compared in precision and dilution linearity. Results: Coating concentration for plate was achieved at 0.1 ㎍/mL for pertussis toxin (PT), 0.15 ㎍/mL for filamentous hemagglutinin antigen (FHA), and 0.25 ㎍/mL for pertactin (PRN). The signal to noise ratio was 22.02 for PT, 14.93 for FHA, and 8.02 for PRN with 0.25% goat serum in phosphate-buffered saline (PBS) as a dilution buffer, and 2% skim milk in PBS as a blocking buffer. Based on the precision results, we assessed the lower limit of quantification by 1, 0.2, and 1.5 EU/mL concentration for PT, FHA, and PRN which met the ICH (International Council for Harmonization) M10 criteria of a 25% accuracy and total error of 40%. In specificity, homologous serum was spiked into heterologous serum and the accuracy met the criteria. There was no difference in the results between RFL and PLL calculations (p-value=0.3207 for PT, 0.7394 for FHA, 0.2109 for PRN). Conclusion: ELISA validated with RFL calculation method in this study is a relatively accurate assay for mouse humoral immunogenicity test.

• 한국통신학회논문지
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• 제34권1C호
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• pp.131-137
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• 2009

Bin offset carrier (BOC) 신호 동기화 과정은 GPS, Galileo와 같은 위성항법시스템에서 가장 중요한 단계이다. BOC 신호 동기화 과정은 일반적으로, 수신 BOC 신호와 단말기의 BOC 신호 사이의 상관함수를 이용하여 이루서진다. 따라서 BOC 자기상관함수의 다중 첨두 문제는 동기화 오차의 주요한 원인이 된다. 최근 Julien에 의해 BOC 상관함수 상의 주변 첨두 크기를 줄일 수 있는 기법이 제안되었다. 그러나 이 기법은 주변 첨두를 완벽히 제거하지 못하며, 적용할 수 있는 신호도 제한적이다. 본 논문에서는 주변 첨두가 완벽히 제거된 새로운 상관함수를 제안하였다. 제안한 상관함수는 sine 위상 및 cosine 위상의 BOC 신호 모두에 적용할 수 있으며, 주변 첨두를 완벽히 제거할 수 있다. 또한 제안한 상관함수를 효율적으로 구현할 수 있는 상관기 구조도 제안하였다.

• Journal of Positioning, Navigation, and Timing
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• 제12권1호
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• pp.59-65
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• 2023

A GNSS receiver must perform signal acquisition to estimate the code phase and Doppler frequency of the incoming satellite signals, which are essential information for baseband signal processing. Modernized GNSS signals have different modulation schemes and long PRN code lengths from legacy signals, which makes it difficult to acquire the signals and increases the computational complexity and time. This paper proposes a novel FFT/Inverse-FFT with baseband resampling to resolve the aforementioned challenges. The suggested algorithm uses a single block only for the FFT and thereby requires less hardware resources than conventional structures such as Double Block Zero Padding (DBZP). Experimental results based on a MATLAB simulation show this algorithm can successfully acquire GPS L1C/A, GPS L2C, Galileo E1OS, and GPS L5.