• Title/Summary/Keyword: differential code bias

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Test Results of Wide-Area Differential Global Positioning System with Combined Use of Precise Positioning Service and Standard Positioning Service Receiver

  • Kim, Kap Jin;Ahn, Jae Min
    • Journal of Positioning, Navigation, and Timing
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    • v.10 no.1
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    • pp.43-48
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    • 2021
  • Most existing studies on the wide-area differential global positioning system (WADGPS) used standard positioning service (SPS) receivers in their observation reference stations which provide the central control station global positioning system (GPS) measurements to generate augmentation data. In the present study, it is considered to apply a precise positioning service (PPS) receiver to an observation reference station which is located in the threatened jamming area. Therefore, the reference station network consists of a PPS receiver based observation reference station and SPS receiver based observation reference stations. In this case, to maintain correction performance P1C1 differential code bias (DCB) should be compensated. In this paper, P1C1 DCB estimation algorithm was applied to the PPS/WADGPS system and performance test results using measurements in the Korean Peninsula were presented.

Generation of Korean Ionospheric Total Electron Content Map Considering Differential Code Bias (Differential Code Bias를 고려한 한반도 전리층 총전자수 지도 생성)

  • Lee, Chang-Moon;Kim, Ji-Hye;Park, Kwan-Dong
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.29 no.3
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    • pp.293-301
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    • 2011
  • The ionospheric delay is the largest error source in GPS positioning after the SA effect has been turned off in May, 2000. In this study, we used 44 permanent GPS stations being operated by National Geographic Information Institute (NGII) to estimate Total Electron Content (TEC) based on pseudorange measurements phase-leveled by a linear combination with carrier phases. The Differential Code Bias (DCB) of GPS satellites and receivers was estimated and applied for an accurate estimation of the TEC. To validate our estimates of DCB, changes of TEC values after DCB application were investigated. As a result, the RMS error went down by about an order of magnitude; from 35~45 to 3~4 TECU. After the DCB correction, ionospheric TEC maps were produced at a spatial resolution of $1^{\circ}{\times}1^{\circ}$. To analyze the effect of the number of sites used for map generation on the accuracy of TEC values, we tried 10, 20, 30, and 44 stations and the RMS error was computed with the Global Ionosphere Map as the truth. While the RMS error was 5.3 TECU when 10 sites are used, the error reduced to 3.9 TECU for the case of 44 stations.

Receiver DCB Estimation and Analysis by Types of GPS Receiver

  • Choi, Byung-Kyu;Chung, Jong-Kyun;Cho, Jeong-Ho
    • Journal of Astronomy and Space Sciences
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    • v.27 no.2
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    • pp.123-128
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    • 2010
  • This paper analyzes that the global positioning system (GPS) receiver differential code bias (DCB) has effect on the estimation the ionosphere total electron content (TEC). The data from nine permanent GPS sites of the Korea Astronomy and Space Science Institute (KASI) were used for the estimation of the receiver DCB before (Trimble 4000 SSi) and after (Trimble NetRS) the receiver replacement, using the singular value decomposition method. The results showed that the estimated mean value of the receiver DCB varied from 0.11 ns (nanosecond) to 7.54 ns before the receiver replacement, but the receiver DCBs shoed large values than 20 ns except some stations after the replacement. The receiver DCB showed a relatively large difference by types of the receivers, and, as a result, it had a great effect on the estimation the ionosphere TEC using GPS.

GPS Receiver and Satellite DCB Estimation using Ionospheric TEC (전리층 TEC를 이용한 GPS 수신기와 위성의 DCB 추정)

  • Choi, Byung-Kyu;Cho, Sung-Ki;Lee, Sang-Jeong
    • Journal of Astronomy and Space Sciences
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    • v.26 no.2
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    • pp.221-228
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    • 2009
  • We estimated the receiver and satellite differential code bias(DCB) based on the ionospheric total electron content(TEC) estimation method. The GPS network which has been operated by the Korea Astronomy and Space Science Institute(KASI) was designed to calculate TEC. The receiver and satellite DCB values were obtained from the weighted least square method with time interval for one hour. The results represented that the receiver DCB values are mostly varying within ${\pm}2m$ meter and are derived comparatively stable within three days. The estimated mean values of the satellite DCB show the maximum and minimum values of 4.09 nano-second(ns), -6.28ns respectively. We could detect great variations of TEC over 9 TECU difference at any time when the DCB sets were applied to TEC estimation.

3차원적 도핑 분포 측정을 위한 SCM 응용 방법 (The SCM Method for Three-Dimensional Dopant Profiles)

  • Lee Jun-Ha;Lee Hoong-Joo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.7 no.1
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    • pp.7-11
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    • 2006
  • Through SCM modeling, we found that the depletion layer in silicon was of a form of a spherical capacitor with the SCM tip biased. Two-dimensional (2D) finite differential method code with a successive over relaxation (SOR) solver has been developed to model the measurements by SCM of a semiconductor wafer that contains an ion-implanted impurity region. Then, we theoretically analyzed the spherical capacitor and determined the total depleted-volume charge Q, capacitance C, and the rate of capacitance change with bias dC/dV. It is very important to observe the depleted carriers' movement in the silicon layer by applying the bias to the tip. So, we calculated the depleted-volume charge, considering different factors such as tip size, oxide thickness, and applied bias (dc+ac), which have an influence on potential and depletion charges.

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Developing GPS Code Multipath Grid Map (CMGM) of Domestic Reference Station (국내 기준국의 GPS 코드 다중경로오차 격자지도 생성)

  • Gyu Min Kim;Gimin Kim;Chandeok Park
    • Journal of Positioning, Navigation, and Timing
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    • v.13 no.1
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    • pp.85-92
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    • 2024
  • This study develops a Global Positioning System (GPS) Code Multipath Grid Map (CMGM) of each individual domestic reference station from the extracted code multipath of measurement data. Multipath corresponds to signal reflection/refraction caused by obstacles around the receiver antenna, and it is a major source of error that cannot be eliminated by differencing. From the receiver-independent exchange format (RINEX) data for two days, the associated code multipath of a satellite tracking arc is extracted. These code multipath data go through bias correction and interpolation to yield the CMGM with respect to the azimuth and elevation angles. The effect of the CMGM on multipath mitigation is then quantitatively analyzed to improve the Root Mean Square (RMS) of averaged pseudo multipath. Furthermore, the single point positioning (SPP) accuracy is analyzed in terms of the RMS of the horizontal and vertical errors. During two weeks in February 2023, the RMSs of the averaged pseudo multipath for five reference stations decreased by about 40% on average after CMGM application. Also, the SPP accuracies increased by about 7% for horizontal errors and about 10% for vertical errors on average after CMGM application. The overall quantitative analysis indicates that the proposed approach will reduce the convergence time of Differential Global Navigation Satellite System (DGNSS), Real-Time Kinematic (RTK), and Precise Point Positioning (PPP)-RTK correction information in real-time to use measurement data whose code multipath is corrected and mitigated by the CMGM.

Development of real-time car tracking system with RGPS and its error analysis (RGPS를 이용한 실시간 차량관제시스템 구현과 오차분석)

  • Go, Sun-Jun;Lee, Ja-Sung
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.1
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    • pp.15-24
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    • 2000
  • Stand-alone global position system receiver based on C/A code tracking generates position error of 100m mainly due to the selective availability and ionospheric and tropospheric delay errors. The differential GPS is the most commonly used method for removing those bias range error components. The relative GPS, although somewhat restrictive in its use, is ideally suited to the car monitoring system for improved Automatic Vehicle location, especially where the DGPS infrastructure is not available. The RGPS does not require any additional hardware, facility or external infrastructure and can be operated within the system with existing host computer and communication link. This paper presents detailed description of the RGPS concept and its implementation for real-time data processing. Performance of RGPS is evaluated with real data and is compared with DGPS.

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Wide Area Augmentation System Estimating C1P1 DCB (C1P1 DCB를 추정하는 광역보강항법 시스템)

  • Bu, Sung-Chun;So, Hyoung-Min;Kim, Kap-Jin;Lee, Chul-Soo;Kim, Do-Kyoung;Ko, Yo-Han
    • Journal of Advanced Navigation Technology
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    • v.22 no.5
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    • pp.400-408
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    • 2018
  • Wide area augmentation system is a system that generates and transmits correction and Integrity information for use in wide area. Typical system is SBAS. In the United States, it operates under the name WAAS, EGNOS in Europe, MSAS in Japan, SDCM in Russia, GAGAN in India. it is developing Korean SBAS which named KASS by 2022 in Korea. SBAS is a standard System that is operated as civil aviation service base and set as international standards by ICAO. So the correction data can only is used for civil SPS receiver. In this paper, we discuss C1P1 DCB estimation which need to use SPS correction service for PPS receiver. Then we analyze C1P1 DCB correction effect under standalone Satellite Navigation and method to use PPS receiver under SPS DGPS. Finally we organize wide area augmentation system for PPS receiver and analysis performance.