• Title/Summary/Keyword: Precision Navigation

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A Study on Development of the GPIR system Receiver Using G-Files (G-File을 이용한 GPIR 시스템 수신기 개발)

  • Choi, Sang-Kyoon;Kim, Jae-Saeng
    • Journal of Advanced Navigation Technology
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    • v.14 no.3
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    • pp.336-342
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    • 2010
  • GPIR(GPS Position Information Revision) system is a new concept of GPS system which utilizes database containing the location of taking a picture by the existing GPS, an angle between a camera and a subject and the location information of buildings and minimizes the GPS's own margin of error and there by provides the services, such as location-guiding via GPS and way-guiding via navigation in an exact and precision way more than before. GPIR system comprehends the location of taking photos via GPS information saved in G-files, searches database in the direction of taking a photo at a photo-taking position via location information and the photo-taking directional angle. And GPIR system corrects the GPS information searched to the location of a subject, again saves such information in a G-file and is ready for receiving more detailed location of the subject. This study explores into the design and development of a receiver which a GPIR user is able to utilize its system as well as the design of the receiver's prototypes.

A Study on the DGPS Service Utilization for the Low-cost GPS Receiver Module Based on the Correction Projection Algorithm (위성배치정보와 보정정보 맵핑 알고리즘을 이용한 저가형 GPS 수신기의 DGPS 서비스 적용 방안 연구)

  • Park, Byung-Woon;Yoon, Dong-Hwan
    • Journal of Navigation and Port Research
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    • v.38 no.2
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    • pp.121-126
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    • 2014
  • This paper suggests a new algorithm to provide low-cost GPS modules with DGPS service, which corrects the error vector in the already-calculated position by projecting range corrections to position domain using the observation matrix calculated from the satellite elevation and azimuth angle in the NMEA GPGSV data. The algorithm reduced the horizontal and vertical RMS error of U-blox LEA-5H module from 1.8m/5.8m to 1.0m/1.4m during the daytime. The algorithm has advantage in improving the performance of low-cost module to that of DGPS receiver by a software update without any correction in hardware, therefore it is expected to contribute to the vitalization of the future high-precision position service infrastructure by reducing the costumer cost and vender risk.

SBAS Non-Standard Data Transmission Method for Korea Augmentation Satellite System Applications (KASS 활용을 위한 위성기반 보강항법시스템(SBAS) 비규격 데이터 전송 방법 연구)

  • Park, Jae-ik;Lee, Eunsung;Heo, Moon-beom;Nam, Gi-wook
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.12
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    • pp.1861-1867
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    • 2016
  • Korea augmentation satellite system (KASS), which is a satellite-based augmentation system tailored for Korea, was launched for development in 2014. SBAS is a standard for aviation but it can also be utilized in non-aviation applications. The type and content of transmitted in SBAS data format are restricted. In order to utilize SBAS in fields that require the precision within centimeters, additional information has to be transmitted. It is important that data transmitted in nonstandard SBAS data not affect any operation of SBAS equipment. In this paper, we propose a non-standard SBAS data transmission method applicable to non-aviation applications that does not affect aviation SBAS receivers.

Fast Ambiguity Resolution using Galileo Multiple Frequency Carrier Phase Measurement

  • Ji, Shengyue;Chen, Wu;Zhao, Chunmei;Ding, Xiaoli;Chen, Yongqi
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.1
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    • pp.179-184
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    • 2006
  • Rapid and high-precision positioning with a Global Navigation Satellite System (GNSS) is feasible only when very precise carrier-phase observations can be used. There are two kinds of mathematical models for ambiguity resolution. The first one is based on both pseudorange and carrier phase measurements, and the observation equations are of full rank. The second one is only based on carrier phase measurement, which is a rank-defect model. Though the former is more commonly used, the latter has its own advantage, that is, ambiguity resolution will be freed from the effects of pseudorange multipath. Galileo will be operational. One of the important differences between Galileo and current GPS is that Galileo will provide signals in four frequency bands. With more carrier-phase data available, frequency combinations with long equivalent wavelength can be formed, so Galileo will provide more opportunities for fast and reliable ambiguity resolution than current GPS. This paper tries to investigate phase only fast ambiguity resolution performance with four Galileo frequencies for short baseline. Cascading Ambiguity Resolution (CAR) method with selected optimal frequency combinations and LAMBDA method are used and compared. To validate the resolution, two tests are used and compared. The first one is a ratio test. The second one is lower bound success-rate test. The simulation test results show that, with LAMBDA method, whether with ratio test or lower bound success rate validation criteria, ambiguity can be fixed in several seconds, 8 seconds at most even when 1 sigma of carrier phase noise is 12 mm. While with CAR method, at least about half minute is required even when 1 sigma of carrier phase noise is 3 mm. It shows that LAMBDA method performs obviously better than CAR method.

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A quantitative analysis of synthetic aperture sonar image distortion according to sonar platform motion parameters (소나 플랫폼의 운동 파라미터에 따른 합성개구소나 영상 왜곡의 정량적 분석)

  • Kim, Sea-Moon;Byun, Sung-Hoon
    • The Journal of the Acoustical Society of Korea
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    • v.40 no.4
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    • pp.382-390
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    • 2021
  • Synthetic aperture sonars as well as side scan sonars or multibeam echo sounders have been commercialized and are widely used for seafloor imaging. In Korea related research such as the development of a towed synthetic aperture sonar system is underway. In order to obtain high-resolution synthetic aperture sonar images, it is necessary to accurately estimate the platform motion on which it is installed, and a precise underwater navigation system is required. In this paper we are going to provide reference data for determining the required navigation accuracy and precision of navigation sensors by quantitatively analyzing how much distortion of the sonar images occurs according to motion characteristics of the platform equipped with the synthetic aperture sonar. Five types of motions are considered and normalized root mean square error is defined for quantitative analysis. Simulation for error analysis with parameter variation of motion characteristics results in that yaw and sway motion causes the largest image distortion whereas the effect of pitch and heave motion is not significant.

Performance Analysis of Vision-based Positioning Assistance Algorithm (비전 기반 측위 보조 알고리즘의 성능 분석)

  • Park, Jong Soo;Lee, Yong;Kwon, Jay Hyoun
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.37 no.3
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    • pp.101-108
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    • 2019
  • Due to recent improvements in computer processing speed and image processing technology, researches are being actively carried out to combine information from camera with existing GNSS (Global Navigation Satellite System) and dead reckoning. In this study, developed a vision-based positioning assistant algorithm to estimate the distance to the object from stereo images. In addition, GNSS/on-board vehicle sensor/vision based positioning algorithm is developed by combining vision based positioning algorithm with existing positioning algorithm. For the performance analysis, the velocity calculated from the actual driving test was used for the navigation solution correction, simulation tests were performed to analyse the effects of velocity precision. As a result of analysis, it is confirmed that about 4% of position accuracy is improved when vision information is added compared to existing GNSS/on-board based positioning algorithm.

Time Synchronization Technique for GNSS Jamming Monitoring Network System (GNSS 재밍 신호 모니터링 네트워크 시스템을 위한 독립된 GNSS 수신기 간 시각 동기화 기법)

  • Jin, Gwon gyu;Song, Young jin;Won, Jong hoon
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.20 no.3
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    • pp.74-85
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    • 2021
  • Global Navigation Satellite System (GNSS) receivers are intrinsically vulnerable to radio frequency jamming signals due to the fundamental property of radio navigation systems. A GNSS jamming monitoring system that is capable of jamming detection, classification and localization is essential for infrastructure for autonomous driving systems. For these 3 functionalities, a GNSS jamming monitoring network consisting of a multiple of low-cost GNSS receivers distributed in a certain area is needed, and the precise time synchronizaion between multiple independent GNSS receivers in the network is an essential element. This paper presents a precise time synchronization method based on the direct use of Time Difference of Arrival (TDOA) technique in signal domain. A block interpolation method is additionally incorporated into the method in order to maintain the precision of time synchronization even with the relatively low sampling rate of the received signals for computational efficiency. The feasibility of the proposed approach is verified in the numerical simualtions.

Carrier Phase Based Cycle Slip Detection and Identification Algorithm for the Integrity Monitoring of Reference Stations

  • Su-Kyung Kim;Sung Chun Bu;Chulsoo Lee;Beomsoo Kim;Donguk Kim
    • Journal of Positioning, Navigation, and Timing
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    • v.12 no.4
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    • pp.359-367
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    • 2023
  • In order to ensure the high-integrity of reference stations of satellite navigation system, cycle slip should be precisely monitored and compensated. In this paper, we proposed a cycle slip algorithm for the integrity monitoring of the reference stations. Unlike the legacy method using the Melbourne-Wübbena (MW) combination and ionosphere combination, the proposed algorithm is based on ionosphere combination only, which uses high precision carrier phase observations without pseudorange observations. Two independent and complementary ionosphere combinations, Ionospheric Negative (IN) and Ionospheric Positive (IP), were adopted to avoid insensitive cycle slip pairs. In addition, a second-order time difference was applied to the IN and IP combinations to minimize the influence of ionospheric and tropospheric delay even under severe atmosphere conditions. Then, the cycle slip was detected by the thresholds determined based on error propagation rules, and the cycle slip was identified through weighted least square method. The performance of the proposed cycle slip algorithm was validated with the 1 Hz dual-frequency carrier phase data collected under the difference levels of ionospheric activities. For this experiment, 15 insensitive cycle slip pairs were intentionally inserted into the raw carrier phase observations, which is difficult to be detected with the traditional cycle slip approach. The results indicate that the proposed approach can successfully detect and compensate all of the inserted cycle slip pairs regardless of ionospheric activity. As a consequence, the proposed cycle slip algorithm is confirmed to be suitable for the reference station where real time high-integrity monitoring is crucial.

Performance Analysis of GNSS Residual Error Bounding for QZSS CLAS

  • Yebin Lee;Cheolsoon Lim;Yunho Cha;Byungwoon Park;Sul Gee Park;Sang Hyun Park
    • Journal of Positioning, Navigation, and Timing
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    • v.12 no.3
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    • pp.215-228
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    • 2023
  • The State Space Representation (SSR) method provides individual corrections for each Global Navigation Satellite System (GNSS) error components. This method can lead to less bandwidth for transmission and allows selective use of each correction. Precise Point Positioning (PPP) - Real-Time Kinematic (RTK) is one of the carrier-based precise positioning techniques using SSR correction. This technique enables high-precision positioning with a fast convergence time by providing atmospheric correction as well as satellite orbit and clock correction. Currently, the positioning service that supports PPP-RTK technology is the Quazi-Zenith Satellite System Centimeter Level Augmentation System (QZSS CLAS) in Japan. A system that provides correction for each GNSS error component, such as QZSS CLAS, requires monitoring of each error component to provide reliable correction and integrity information to the user. In this study, we conducted an analysis of the performance of residual error bounding for each error component. To assess this performance, we utilized the correction and quality indicators provided by QZSS CLAS. Performance analyses included the range domain, dispersive part, non-dispersive part, and satellite orbit/clock part. The residual root mean square (RMS) of CLAS correction for the range domain approximated 0.0369 m, and the residual RMS for both dispersive and non-dispersive components is around 0.0363 m. It has also been confirmed that the residual errors are properly bounded by the integrity parameters. However, the satellite orbit and clock part have a larger residual of about 0.6508 m, and it was confirmed that this residual was not bounded by the integrity parameters. Users who rely solely on satellite orbit and clock correction, particularly maritime users, thus should exercise caution when utilizing QZSS CLAS.