• 대한임베디드공학회논문지
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• 제4권4호
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• pp.148-155
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• 2009

Precise localization heavily relies on the accuracy of its underlying ranging technique. It has been known that the Chirp Spread Spectrum (CSS) defined in the IEEE 802.15.4a provides more dependable ranging accuracy than the Received Signal Strength Indicator (RSSI) in the IEEE 802.15.4. This paper examines the accuracy of the CSS-based ranging technique in the indoor/outdoor environments and discovers its consistent inaccuracy in different environments. Next, it proposes an error-correction architecture for the CSS-based ranging technique that exploits the per-environment consistent inaccuracy information and user visiting patterns (represented by weights for each environment).

• Journal of Information Processing Systems
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• 제16권1호
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• pp.155-170
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• 2020

Passive ranging is a critical part of machine vision measurement. Most of passive ranging methods based on machine vision use binocular technology which need strict hardware conditions and lack of universality. To measure the distance of an object placed on horizontal plane, we present a passive ranging method based on monocular vision system by smartphone. Experimental results show that given the same abscissas, the ordinatesis of the image points linearly related to their actual imaging angles. According to this principle, we first establish a depth extraction model by assuming a linear function and substituting the actual imaging angles and ordinates of the special conjugate points into the linear function. The vertical distance of the target object to the optical axis is then calculated according to imaging principle of camera, and the passive ranging can be derived by depth and vertical distance to the optical axis of target object. Experimental results show that ranging by this method has a higher accuracy compare with others based on binocular vision system. The mean relative error of the depth measurement is 0.937% when the distance is within 3 m. When it is 3-10 m, the mean relative error is 1.71%. Compared with other methods based on monocular vision system, the method does not need to calibrate before ranging and avoids the error caused by data fitting.

• 한국통신학회논문지
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• 제30권12C호
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• pp.1125-1132
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• 2005

초광대역 신호의 높은 시간해상도는 복잡한 다중경로 환경에서의 정밀한 거리추정 및 위치추적 을 가능하게 한다. 그러나 신호의 도착신호 추정시 발생하는 큰 추정오차의 발생은 거리추정의 정확도를 저하시키는 요인이 된다. 본 논문에서는 다중경로, 다중사용자 환경에서 초광대역 거리추정의 성능을 평가한다. 상호상관을 이용한 직렬검색 알고리듬을 적용할 때 발생하는 추정오차를 분석하고 모의실험 결과를 개시한다.

• Journal of Astronomy and Space Sciences
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• 제35권1호
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• pp.39-46
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• 2018

In this study, the performance of ranging techniques for the Korea Pathfinder Lunar Orbiter (KPLO) space communication system is investigated. KPLO is the first lunar mission of Korea, and pseudo-noise (PN) ranging will be used to support the mission along with sequential ranging. We compared the performance of both ranging techniques using the criteria of accuracy, acquisition probability, and measurement time. First, we investigated the end-to-end accuracy error of a ranging technique incorporating all sources of errors such as from ground stations and the spacecraft communication system. This study demonstrates that increasing the clock frequency of the ranging system is not required when the dominant factor of accuracy error is independent of the thermal noise of the ranging technique being used in the system. Based on the understanding of ranging accuracy, the measurement time of PN and sequential ranging are further investigated and compared, while both techniques satisfied the accuracy and acquisition requirements. We demonstrated that PN ranging performed better than sequential ranging in the signal-to-noise ratio (SNR) regime where KPLO will be operating, and we found that the T2B (weighted-voting balanced Tausworthe, voting v = 2) code is the best choice among the PN codes available for the KPLO mission.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.2263-2268
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• 2010

본 논문은 SDS-TWR(Symmetric Double-Sided Two_Way Ranging)의 Ranging 오차를 보정하여 위치인식 성 능을 향상시키는 방법으로 비컨노드의 거리별 Ranging 오차의 평균 값을 이용하여 Ranging 오차를 보정하는 알고리즘($CA_d$)과, 균등거리비율의 적용으로 Ranging 오차를 보정하는 알고리즘(AEDR)이 적용된 하이브리드형 위치인식 보정 알고리즘($A_{HB}$)을 제안하고, 위치인식 실험을 통해 성능을 분석하였다. 실험결과, $A_{HB}$ 는 전체 32개의 좌표 중 28개 좌표에서 오차 개선이 이루어졌고, 설정한 3개의 오차크기 영역에서 최소한 70%이상의 오차 개선이 이루어졌음을 확인하였다. 또한 32개 좌표에서 발생한 평균 오차 2.67m를 1.19m로 55.4% 보정하였으며 특히 3m 이상의 오차크기 영역에서의 보정 성능은 90% 이상으로 매우 우수함을 확인하였다. 이와 같은 결과를 볼 때, $A_{HB}$ 는 $CA_d$와 AEDR이 각각 수행되었을 때 보다 오차 개선 비율 및 보정 성능이 더 우수함을 확인하였다.

• 한국음향학회지
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• 제43권3호
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• pp.324-334
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• 2024

파면곡률거리추정(Wavefront Curvature Ranging, WCR)은 음파의 파면곡률로부터 음원의 거리를 추정하는 방법이다. 기존의 파면곡률거리추정은 음속을 상수로 가정하고 삼각법으로 거리를 추정한다. 이 가정 때문에 해저면반사경로가 뚜렷하게 분리되는 해양환경에서는 거리 오차가 발생한다. 거리 오차를 줄이기 위해 해양의 음속구조를 적용하고 최대우도추정(Maximum Likelihood Estimation, MLE)방법으로 거리를 추정하는 정합 파면곡률거리추정(Matched Wavefront Curvature Ranging, MWCR) 을 제안하였다. 정합 파면곡률거리추정의 시뮬레이션 결과로부터 거리 오차의 감소를 확인하였다. 향후에 실측 신호로부터 거리 추정의 신뢰성을 확인하면 소나 시스템에 적용 가능할 것이다.

• 한국산학기술학회논문지
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• 제11권4호
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• pp.1248-1253
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• 2010

본 논문은 SDS-TWR(Symmetric Double-Sided Two-Way Ranging)의 Ranging 오차를 보정하기 위하여 균등거리비율 개념을 적용한 위치인식 보정 알고리즘인 AEDR(Algorithm for localization using the concept of Equivalent Distance Rate)을 제안하고, 위치인식 실험을 통해 위치인식 측정 성능을 분석하였다. SDS-TWR의 Ranging 오차는 실험에 의하면 비콘노드와 이동노드의 특정 거리구간에서 평균 1m~8m로 측정되었다. 그러나 제안한 AEDR에 의한 위치인식 성능은 실험을 통해 전체적으로 교내 강당과 복도 모두에서 SDS-TWR 보다 4배 정도 우수하였으며, 측정된 3~10m 이상의 위치인식 오차를 평균 2m 내외로, 3m 이내의 위치인식 오차를 평균 1m 내외로 각각 감소시킬 수 있음을 확인하였다. 특히 AEDR은 LOS(Line Of Sight) 보다 NLOS(Non Line Of Sight)에서 훨씬 더 위치인식 보정 성능이 우수함을 나타내며, 대부분의 센서 네트워크의 환경이 NLOS임을 고려할 때 AEDR이 실제환경에서의 위치인식에 큰 도움을 줄 수 있다고 판단된다.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.658-665
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• 2013

While the chirp signal is extensively used in radar and sonar systems for target decision in wireless communication systems, it has not been widely used for positioning in indoor environments. Recently, the IEEE 802.15.4a standard has adopted the chirp spread spectrum (CSS) as an underlying technique for low-power and low-complexity precise localization. Chirp signal based ranging solutions have been established and deployed but their ranging performance has not been analyzed in multipath environments. This paper presents a ranging performance analysis of a chirp signal and suggests a method to suppress multipath error by using a type of non-linear chirp signal. Multipath ranging performance is evaluated using a conventional linear chirp signal and the proposed non-linear chirp signal. We verify the feasibility of both methods using two-ray multipath model simulation. Our results demonstrate that the proposed non-linear chirp signal can successfully suppress the multipath error.

• 한국정밀공학회지
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• 제34권3호
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• pp.191-197
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• 2017

Light detection and ranging (LiDAR) is one of the most efficient technologies to obtain the topographic and bathymetric map of coastal zones, superior to other technologies, such as sound navigation and ranging (SONAR) and synthetic aperture radar (SAR). However, the measurement results using LiDAR are vulnerable to environmental factors. To achieve a correspondence between the acquired LiDAR data and reality, error sources must be considered, such as the water surface slope, water turbidity, and seafloor slope. Based on the knowledge of those factors' effects, error corrections can be applied. We concentrated on the effect of the seafloor slope on LiDAR waveforms while restricting other error sources. A simulation regarding in-water beam scattering was conducted, followed by an investigation of the correlation between the seafloor slope and peak timing of return waveforms. As a result, an equation was derived to correct the depth error caused by the seafloor slope.

• 한국항공운항학회지
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• 제17권1호
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• pp.52-57
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• 2009

One of the error sources for microwave ranging is the instability of the oscillator that drives the microwave signals. Dual one-way ranging (DOWR) minimizes the oscillator effect by combining two one-way carrier phase signals from two transmitter/receiver instrument. The DOWR is first implemented in the GRACE (Gravity Recovery and Climate Experiment) satellites. Direct evaluation of the DOWR is not possible due to its extremely high accuracy. The flight performance of the GRACE DOWR is analyzed by applying several indirect methods. Comparison with the design noise level is discussed.