• 음성과학
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• 제3권
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• pp.167-176
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• 1998

Conventional time-scale modification methods have the problem that as the modification rate gets higher the time-scale modified speech signal becomes less intelligible, because they ignore the effect of articulation rate on speech characteristics. Results of research on speech perception show that the timing information of transient portions of a speech signal plays an important role in discriminating among different speech sounds. Inspired by this fact, we propose a novel scheme for modifying the time-scale of speech. In the proposed scheme, the timing information of the transient portions of speech is preserved, while the steady portions of speech are compressed or expanded somewhat excessively for maintaining overall time-scale change. In order to identify the transient and steady portions of a speech signal, we employ a simple method using LPC cepstral distance between neighboring frames. The result of the subjective preference test indicates that the proposed method produces performance superior to that of the conventional SOLA method, especially for very fast playback case.

• Journal of Positioning, Navigation, and Timing
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• 제10권3호
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• pp.207-214
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• 2021

A new positioning technique for positioning of LTE base stations is proposed. The positioning information of the base station is absolutely necessary for model-based wireless positioning, and is required in some of the various merhodologies for estimating signals in an uncorrected area when construnting a database for fingerprinting-based positioning. Using the acquired location-based Reference Signal Received Power (RSRP) information to estimate the location of the base station, it is impossible with the existing trilateration methods. Therefore, in this paper, a method using reference particles is proposed. Particles are randomly generated in the application area, and signal propagation modeling is performed assuming that a base station is located in each particle. Based on this, the errors of measurements are calculated. The particle group with the minimum measurement errors is selected, the position of the base station is estimated through weighted summation, and the signal propagation model of the corresponding base station is built at the same time. The performance of the proposed technology is verified using data acquired in Seocho-dong, Seoul.

• Journal of Positioning, Navigation, and Timing
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• 제10권2호
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• pp.131-137
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• 2021

The Angle-of-Arrival (AOA) estimation in real time is one of core technologies for the real-time tracking system, such as a radar or a satellite. Although AOA estimation algorithms for various antenna types have been studied, most of them are for the single-shaped array antenna suitable to the specific frequency. In this paper, we propose the cascade AOA estimation algorithm for the combined array antenna with Uniform Rectangular Frame Array (URFA) and Uniform Circular Array (UCA), with the excellent performance for various frequencies. The proposed technique is consisted of Capon for roughly finding AOA groups with multiple signal AOAs and Beamspace Multiple Signal Classification (MUSIC) for estimating the detailed signal AOA in the AOA group, for the combined array antenna. In addition, we provide computer simulation results for verifying the estimation performance of the proposed algorithm.

• Journal of Positioning, Navigation, and Timing
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• 제10권1호
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• pp.21-28
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• 2021

In order to develop a Korea Positioning System (KPS) as part of key national infrastructure, independent navigation signal design is essential. The designed signal candidates must coexist with existing or planned GNSS signals within the limited frequency band. This requires a RF compatibility assessment, which can be performed using the Spectral Separation Coefficient (SSC) and Effective Carrier to Noise Density Ratio (Effective C/N0), for navigation signals. Thus, in this paper, the analysis of RF compatibility between the designed signal candidates and the existing GNSS signals is carried out based on analytical and numerical techniques.

• 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.

• Journal of Positioning, Navigation, and Timing
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• 제13권2호
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• pp.207-213
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• 2024

This paper examines the frame boundary detection performance for a satellite navigation augmentation signal orthogonally modulated with Hadamard code to determine the number of message preamble bits. Simulation results show that, even in weak signal environments, designing the message preamble with 32 bits is recommended for achieving stable frame boundary detection.

• 융합신호처리학회논문지
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• 제23권1호
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• pp.1-7
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• 2022

타이밍벨트는 동력전달 요소로서 V벨트와 기어의 장점을 살린 톱니붙이 전동 벨트로서 미끄러지지 않고 소음도 적어 기구에서 회전축이나 직선 운동에서 동력을 전달할 때 동력 전달 장치로 사용되고 있다. 기어처럼 등간격의 홈을 가진 벨트 풀리와 홈에 정확히 맞물리도록 동일한 간격의 홈을 가진 타이밍 벨트를 통해 회전을 정확하게 전달할 수가 있다. 특히 출력축에 타이밍벨트가 사용된 메커니즘에서 타이밍벨트의 강성을 포함한 동적 특성이 시스템 전달 특성을 결정하게 되므로 그 중요성이 커진다. 본 논문에서는 제한된 범위의 움직임을 갖는 타이밍 벨트에 적용하여 강성을 증가시킬 수 있는 강성 강화 벨트를 제안하였다. 강성 강화 벨트의 동특성을 연구하기 위하여 강성 강화 벨트에 대한 운동방정식을 수립하고, 강성 강화 벨트에 대한 시뮬레이션 모델을 만들어 분석을 수행하였다. 운동 방정식과 시뮬레이션 모델의 분석 결과를 확인하기 위하여 강성 강화 벨트를 사용한 1축 회전 실험 장치를 제작하고 실험을 수행하였다. 운동 방정식, 시뮬레이션 모델, 실험을 통하여 제안한 강성 강화 벨트를 적용하면 타이밍벨트의 강성과 동특성을 개선할 수 있음을 확인하였다.

• Journal of Positioning, Navigation, and Timing
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• 제4권4호
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• pp.173-180
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• 2015

In this study, an algorithm that detects a spoofing signal for a GPS L1 signal was proposed, and the performance was verified through RF spoofing signal simulation. The proposed algorithm determines the reception of a spoofing signal by detecting a correlation distortion of GPS L1 C/A code caused by the spoofing signal. To detect the correlation distortion, a detection criterion of a spoofing signal was derived from the relationship among the Early, Prompt, and Late tap correlation values of a receiver correlator; and a detection threshold was calculated from the false alarm probability of spoofing signal detection. In this study, an RF spoofing environment was built using the GSS 8000 simulator (Spirent). For the RF spoofing signal generated from the simulator, the RF spoofing environment was verified using the commercial receiver DL-V3 (Novatel Inc.). To verify the performance of the proposed algorithm, the RF signal was stored as IF band data using a USRP signal collector (NI) so that the data could be processed by a CNU software receiver (software defined radio). For the performance of the proposed algorithm, results were obtained using the correlation value of the software receiver, and the performance was verified through the detection of a spoofing signal and the detection time of a spoofing signal.

• 대한교통학회지
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• 제23권7호
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• pp.43-52
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• 2005

실시간 신호제어군의 결합 및 분리를 통한 실시간 연동신호교차로군 조절은 최근에 강조되고 있는 첨단교통신호제어시스템의 기능 중 하나이다. 필요에 따라 연동축 및 연동방향을 능동적으로 조절하는 과정에서 신호제어군의 실시간 분리 결합 상황이 발생하며, 이때 필수적으로 옵셋을 재조정을 위한 '옵셋전이시간'이 소요된다. 이 때 '옵셋전이시간'이 필요이상 긴 경우 비효율적인 신호운영변수가 장시간 적용됨으로 인하여, 필요이상 짧은 경우 갑작스런 신호시간 변화에 따른 교통흐름 장애 (turbulence)로 인하여 해당 구간 신호제어 운영 효율성이 저하될 수 있다. 현재의 국내 실시간 신호제어시스템은 3주기에서 5주기에 걸쳐 '옵셋전이시간'을 적용할 것을 개략적으로 권고하고 있으나 해당분야에서의 공학적 연구가 미비하다. 본 연구에서는 네 가지 다른 옵셋전이시간(한 주기길이, 두 주기길이, 세 주기길이, 네 주기길이)를 활용하는 네 가지 다른 옵셋전이방법의 성능을 CORSIM 모의실험 환경에서 CORSIM RTE 기능을 이용하여 분석하고 비교하였다. 설정된 총 15가지 상이한 교통소통 상황을 토대로 다양한 무작위난수를 적용하는 모의실험을 수행하며 수집된 평균 차량지체자료를 통계 분석한 결과 한 주기 길이 옵셋전이시간이 본 연구에서 설정된 모든 교통상황에서 기타 옵셋전이시간보다 우수하거나(낮은 지체도) 적어도 동일한 것으로 분석되었다. 본 연구는 한 주기 '옵셋전이길이' 적용을 옵셋전이 적용지침으로 사용할 것을 제안한다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2012년도 춘계학술대회
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• pp.80-81
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• 2012

우리 사회는 전력의 생산 및 배전 시스템, 통신기술, 텔레커뮤니케이션, 금융시스템, 수송시스템 등의 효율적이고 정상적으로 운영 됨으로써 국가의 중대한 인프라로 구성이 된다. 이런 중대한 인프라 및 그 응용분야는 P.N.T(Positioning, Navigation, Timing) 시스템에 의존하고 있는데 이 P.N.T가 텔레커뮤니케이션(시각동기), 금융시장(시각동기), 물류관리(위치, 항법, 시각동기), 수송(위치, 항법, 시각동기) 등의 버팀목이 된다. 국가적으로 P.N.T 서비스를 지속적으로 사용할 수 있도록 GPS 시스템과 별도의 항법시스템 구축이 필요하여 안정적으로 PNT 서비스를 할 수 있는 시스템 구축에 대한 연구를 하였다.