• 한국항행학회논문지
• /
• 제28권1호
• /
• pp.155-158
• /
• 2024

Multipath, a major error source in urban GNSS positioning (global navigation satellite system), pose a challenge due to its site-dependent nature, varying with the user's signal reception environment. In our previous study, we introduced a technique generating GNSS multipath map in urban canyon. However, due to uncertainty in initial GNSS positions, applying multipath maps required generating multiple candidate positions. In this study, we present an efficient method for applying multipath maps by projecting the multipath correction in position domain. This approach effectively applies multipath maps, addressing the challenges posed by urban user position uncertainties.

• 한국측량학회지
• /
• 제36권5호
• /
• pp.403-412
• /
• 2018

Recently, GNSS (Global Navigation Satellite System)-derived orthometric height determination has been studied to improve the time and cost-effectiveness of traditional leveling surveying. However, the accuracy of this new survey method was evaluated when unknown points are located lower than control points. In this study, the accuracy of GNSS-derived orthometric height was examined using TPs (Triangulation Points) to verify the stability of surveying in mountainous areas. The GNSS survey data were obtained from Mungyeong, Unbong/Hadong, Uljin, and Jangseong. Three unknown points were surrounded by more than three UCPs (Unified Control Points) or BMs (Benchmarks) following the guideline for applying GNSS-derived orthometric height determination. A newly developed national geoid model, KNGeoid17 (Korean National Geoid 2017), has been applied for determining the orthometric height. In comparison with the official orthometric heights of the TPs, the heights of the unknown points in Mungyeong and Unbong/Hadong differ by more than 20 cm. On the other hand, TPs in Uljin and Jangseong show 15-16 cm of local bias with respect to the official products. Since the precision of official orthometric heights of TPs is known to be about 10 cm, these errors exceed the limit of the precision. Therefore, the official products should be checked to offer more reliable results to surveyors. As an alternative method of verifying accuracy, three different GNSS post-processing software were applied, and the results from each software were compared. The results showed that the differences in the whole test areas did not exceed 5 cm. Therefore, it was concluded that the precision of the GNSS-derived orthometric height was less than 5 cm, even though the unknown points were higher than the control points.

• 한국산학기술학회논문지
• /
• 제19권4호
• /
• pp.593-602
• /
• 2018

본 논문에서는 GNSS 단일기선해석과 망조정을 통한 측량기준점 성과 산정에서 종속기선 포함여부가 미치는 영향을 분석하기 위해 망조정 이론을 바탕으로 실험적인 연구를 수행하였다. 이를 위해 국토지리정보원 운영 위성기준점 50 개소의 관측데이터를 이용하여 종속기선 포함여부에 따라 3가지 형태의 기준점 측량망 구성 및 조정실험을 수행하고, 그 결과를 정확도 표현과 산정성과의 차이 측면에서 분석 하였다. GNSS 망조정에 종속기선을 포함하는 경우 조정성과 차이는 밀리미터 수준으로 매우 제한적이었으나, 망의 자유도와 기하강도 왜곡으로 그 정확도가 과대평가되는 결과를 얻었다. 3가지 경우에 대한 조정성과를 국토지리정보원 고시좌표와 비교했으며, 그 결과 독립기선으로만 이루어진 망의 성과가 가장 높은 일치성을 보였다. 그러나 종속기선을 포함한 조정결과는 상대적으로 큰 차이를 나타내어 성과의 정확도 표현에 왜곡이 있음을 확인할 수 있었다. 이와 같은 분석결과에 따라 GNSS 단일기선해석으로 얻어진 기선벡터의 망조정에서는 기존 성과와의 일치성, 현실적인 정확도 표현 그리고 과대한 데이터 처리에 따른 시간 및 비용 부담을 고려할 때 종속기선을 제외하는 것이 타당할 것으로 판단된다.

• 한국측량학회지
• /
• 제38권5호
• /
• pp.415-423
• /
• 2020

GNSS (Global Navigation Satellite System) is mostly used for high-precise surveys due to its accuracy and efficiency. But this technique does not always fulfill the demanding accuracy in harsh operational environments such as urban canyon and forest. One of the remedies for overcoming this barrier is to compose a heterogeneous surveying network by adopting terrestrial measurements (i.e., distances and angles). Hence, this study dealt with the adjustment of heterogeneous surveying networks consisted of GNSS baseline vectors, distances, horizontal and vertical angles with a view to enhancing their accuracy and so as to derive an appropriate scheme of the measurement combination. Reviewing some technical issues of the network adjustments, the simulation, and experimental studies have been carried out, showing that the inclusion of the terrestrial measurements in the GNSS standalone overall increased the accuracy of the adjusted coordinates. Especially, if the distances, the horizontal angles, or both of them were simultaneously adjusted with GNSS baselines, the accuracy of the GNSS horizontal component was improved. Comparing the inclusion of the horizontal angles with those of the distances, the former has been more influential on accuracy than the latter even though the same number of measurements were employed in the network. On the other hand, results of the GNSS network adjustment together with the vertical angles demonstrated the enhancement of the vertical accuracy. As conclusion, this paper proposes a simultaneous adjustment of GNSS baselines and the terrestrial measurements for an effective scheme that overcomes the limitation of GNSS control surveys.

• 한국항공우주학회지
• /
• 제47권5호
• /
• pp.388-396
• /
• 2019

본 논문은 시험발사체에 탑재된 송신기에서 송신되는 S 대역 신호에 의해 위성항법수신기에서 나타난 RF 신호간섭을 설명하고, 그 원인을 분석한다. 능동형 위성항법안테나의 LNA는 항법위성 신호와 비교하여 상대적으로 신호세기가 매우 높은 S 대역 신호에 의해 포화되었으며, 2개의 S 대역 신호가 위성항법안테나에 수신될 때마다 GNSS 대역에 해당하는 상호변조신호가 LNA에서 발생하였다. 이러한 현상으로 인해 위성항법수신기에서 계산된 항법위성신호의 C/N0가 크게 감쇄하였다. S 대역 신호에 의한 RF 신호간섭을 차단하기 위하여 위성항법안테나 LNA의 설계변경을 수행하였고, 설계변경 전 후의 LNA에 대해 수행한 비교시험을 통하여 설계변경된 LNA에서 S 대역 신호에 의한 RF 신호감쇄 현상이 억제될 수 있음을 확인하였다.

• 한국지리정보학회지
• /
• 제25권4호
• /
• pp.200-209
• /
• 2022

실시간 위치 정보를 제공하는 것이 국가산업의 주요한 목표로 부상하고 있는 실정이다. 이러한 실시간 위치 정보(3차원 공간 정보)를 제공하기 위해서는 위성 측위 방법의 기술 발달이 필수적이다. 그래서 국가에서는 Network RTK GNSS방식을 도입하여, 수요자의 요구에 만족도를 증가시키는 노력을 지속적으로 하고 있다. 본 연구에서는 국토지리정보원에서 제공하고 있는 Network RKT GNSS(Global Navigation Satellite System) 방식 중 VRS(Virtual Reference Station)과 FKP(Flachen-Korrektur Parameter)을 이용하여 통합기준점에서 연속 관측과 단독 관측을 측량하여 정확도 평가를 하였다. 또한 현장에서 급속하게 증가하고 있는 Network RTK GNSS 방법에 대하여 정확도를 제시하여 효율성을 극대화하고자 한다.

• 한국측량학회지
• /
• 제35권5호
• /
• pp.389-404
• /
• 2017

The main purpose of this presented investigation is to build up the BHMS based on GNSS. This proposed monitoring system can conduct the deflection and dynamic characteristics analysis by using only GNSS positioning solution. The general bridge monitoring system being operated recently is composed of a combination of various sensors that are able to conduct deflection monitoring and dynamic characteristics monitoring analysis at the same time. However, GNSS based BHMS has the unique procedure in terms of data analysis. In the other words, GNSS positioning solution is firstly applied to deflection monitoring analysis then, this deflection analysis can be sequentially reflected in the dynamic characteristics. Unfortunately, the adjustment result of GNSS positioning solution estimated through various options and conditions and the process of monitoring analysis has not been fulfilled systematically. This means that different results or analysis value are presented according to the methodology and officers. Most of researches have been focusing on deflection monitoring analysis and some investigation regarding to dynamic characteristics is recently introduced. Moreover, it is not still reported the systematic investigation with regards to proper filtering and analysis methodology. This study was carried out based on a large amount of data, from this, various variables not reported yet are actively considered. Therefore, specific software for both monitoring analysis have been developed.

• 한국측량학회지
• /
• 제36권1호
• /
• pp.1-8
• /
• 2018

To compensate for the shortcomings of spirit leveling, research on the determination of GNSS (Global Navigation Satellite System)-derived orthometric height has been actively carried out. However, most analyses were primarily performed inland. In this study, the influences of the arrangement of control points, observation duration, and geoid model on the accuracy of the GNSS-derived orthometric height have been analyzed to suggest the proper method to apply the determination of GNSS-derived orthometric height to the leveling loop disconnected area. As a result, it was found that two known points located near the unknown points need to be fixed in the leveling loop disconnected area. Further, 3 cm level of accuracy can be achieved if the GNSS survey is performed over two days, for four hours per day. In terms of the geoid model, the latest national geoid model should be applied rather than the EGM08 (Earth Gravitational Model 2008) to minimize regional bias and increase accuracy. Future research is necessary to apply the determination of the GNSS-derived orthometric height technique as a method to connect with the islands because the vertical reference system used inland and that used for the islands in Korea are still different.

• 한국위성정보통신학회논문지
• /
• 제4권1호
• /
• pp.8-13
• /
• 2009

한국전자통신연구원은 다양한 위성항법 응용프로그램과 항법알고리즘을 시험 및 평가하기 위한 소프트웨어 레벨의 환경을 제공하는 위성항법 신호생성 및 수신처리 시뮬레이터 툴을 개발하고 있다. 본 시뮬레이션 툴은 GPS 및 갈릴레오의 디지털 신호 생성하고 이를 수신처리하는 툴을 제공하게 된다. 본 논문에서는 이러한 위성 항법 신호생성 및 수신처리 시뮬레이션 툴의 상세설계 및 모듈 구현에 대하여 기술하고 있다.

• 제어로봇시스템학회논문지
• /
• 제22권11호
• /
• pp.967-976
• /
• 2016

This paper presents a 3D carrier-smoothed GNSS/DR (Global Navigation Satellite System/Dead Reckoning) integrated system for precise ground-vehicle trajectory estimation. For precise DR navigation on sloping roads, the AHRS (Attitude Heading Reference System) methodology is employed. By combining the integrated carrier phase of GNSS and DR sensor measurements, a vehicle trajectory with an accuracy of less than 20cm is obtained even when cycle slip or change of visibility occur. In order to supplement the weak GNSS environment with DR successfully, the DR sensor is precisely compensated for using GNSS Doppler measurements when GNSS visibility is good. By integrating a multi-GNSS receiver with low-cost IMU, a precise 3D navigation system for land vehicles is proposed in this paper. For real-time implementation, a decoupled Kalman filter is employed in the integrated system. Through field experiments, the performance of the proposed system is verified in various road environments, including sloping roads, good-visibility areas, high multi-path areas, and under-ground parking areas.