• Title, Summary, Keyword: ionosphere

Search Result 248, Processing Time 0.028 seconds

An Error Analysis of Precise Point Positioning using Ionosphere Free Combination Measurements (IF 조합 측정치를 사용하는 단독 정밀 측위 오차해석)

  • Park, Sul-Gee;Cho, Deuk-Jae;Shin, Young-Cheol;Park, Chan-Sik
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.18 no.9
    • /
    • pp.871-877
    • /
    • 2012
  • An error analysis of PPP (Precise Point Positioning) using IF (Ionosphere Free) combination is given in this paper. It is shown that the performance of the ordinary model with positions, clock bias, integer ambiguities and ionosphere delay as unknowns is equivalent to that of an ionosphere difference combination where ionosphere delay is cancelled out. Furthermore, it is shown that IF combination is an ionosphere difference combination but not unique. It is also proved that all difference models show same performances. The error analysis evaluated with a hardware simulator and real measurements show that the ionosphere delay is effectively eliminated by IF combination or equivalently by the ionosphere difference combination. However, if bias errors such as troposphere, clock bias or multipath are included in the measurements, the performance of the IF combination is degraded because the bias errors are amplified by the ionosphere difference operation.

On the Electric Fields Produced by Dipolar Coulomb Charges of an Individual Thundercloud in the Ionosphere

  • Kim, Vitaly P.;Hegai, Valery V.
    • Journal of Astronomy and Space Sciences
    • /
    • v.32 no.2
    • /
    • pp.141-144
    • /
    • 2015
  • In this paper we study the transmission of the electrostatic field due to coulomb charges of an individual thundercloud into the midlatitude ionosphere, taking into account the total geomagnetic field integrated Pedersen conductivity of the ionosphere. It is shown that at ionospheric altitudes, a typical thundercloud produces an insignificant electrostatic field whereas a giant thundercloud can drive the horizontal electrostatic field with a magnitude of ${\sim}270{\mu}V/m$ for nighttime conditions.

Analysis of MSAS Ionosphere Correction Messages and the Effect of Equatorial Anomaly (MSAS 전리층 보정정보 및 적도변이에 의한 영향 분석)

  • Jeong, Myeong-Sook;Kim, Jeong-Rae
    • Journal of the Korean Society for Aviation and Aeronautics
    • /
    • v.16 no.2
    • /
    • pp.12-20
    • /
    • 2008
  • Japanese MSAS (Multi-functional Satellite Augmentation System) satellites have been transmitting GPS satellite orbit and ionosphere correction information since 2005. MSAS coverage includes Far East Asia, and it can improve the accuracy and integrity of GPS position solutions in Korea. This research analyzed the ionosphere correction information from the MSAS ionosphere correction data. The ionosphere delay data observed by a dual frequency receiver is compared with the MSAS ionosphere correction data. The variation of MSAS GIVE values are analyzed in connection with the equatorial anomaly and ionosphere scintillation.

  • PDF

Comparison of Ionospheric Spatial Gradient Estimation Methods using GNSS (GNSS를 이용한 전리층 기울기 추정 방법 비교)

  • Jeong, Myeong-Sook;Kim, Jeong-Rae
    • Journal of the Korean Society for Aviation and Aeronautics
    • /
    • v.15 no.2
    • /
    • pp.18-24
    • /
    • 2007
  • The high ionospheric spatial gradient during ionospheric storm is the most concern when applying GNSS(Global Navigation Satellite System) augmentation systems for aircraft precision approach. Since the ionospheric gradient level depends on geographical location as well as the storm, understanding the ionospheric gradient statistics over a specific regional area is necessary for operating the augmentation systems. This paper compares three ionosphere gradient computation methods, direct differentiation between two receivers' ionospheric delay signal for a common satellite, derivation from a grid ionosphere map, and derivation from a plate ionosphere map. The plate map method provides a good indication on the gradient variation behavior over a regional area with limited number of GNSS receivers. The residual analysis for the ionosphere storm detection is discussed as well.

  • PDF

FDTD Analysis of Electromagnetic Wave Propagation in an Inhomogeneous Ionosphere under Arbitrary-Direction Geomagnetic Field

  • Kweon, Jun-Ho;Park, Min-Seok;Cho, Jeahoon;Jung, Kyung-Young
    • Journal of electromagnetic engineering and science
    • /
    • v.18 no.3
    • /
    • pp.212-214
    • /
    • 2018
  • The finite-difference time-domain (FDTD) model was developed to analyze electromagnetic (EM) wave propagation in an inhomogeneous ionosphere. The EM analysis of ionosphere is complicated, owing to various propagation environments that are significantly influenced by plasma frequency, cyclotron frequency, and collision frequency. Based on the simple auxiliary differential equation (ADE) technique, we present an accurate FDTD algorithm suitable for the EM analysis of complex phenomena in the ionosphere under arbitrary-direction geomagnetic field. Numerical examples are used to validate our FDTD model in terms of the reflection coefficient of a single magnetized plasma slab. Based on the FDTD formulation developed here, we investigate EM wave propagation characteristics in the ionosphere using realistic ionospheric data for South Korea.

Performance Analysis of a Satellite-Based Ionosphere Model for WADGPS under Disturbed Ionosphere Condition

  • So, Hyoungmin;Lee, Kihoon;Kim, Kapjin;Park, Junpyo
    • Journal of Positioning, Navigation, and Timing
    • /
    • v.8 no.4
    • /
    • pp.225-232
    • /
    • 2019
  • The satellite-based ionospheric model consists of local first-order plane function parameters for individual satellites and provides excellent accuracy in the flat ionospheric environment of the Korean Peninsula. This paper analyzes the performance of such model under the rapid changes in the ionosphere. Rapid changes in the ionosphere were observed in Korea from September to October 2014, and a satellite-based ionosphere model was applied to Wide Area Differential GPS (WADGPS) to analyze the navigation performance and the performance of estimating ionospheric delay errors. After processing the test data, it was confirmed that there was a deterioration in navigation performance and extrapolation performance in low-latitude areas and analyzed the cause.

Comparison of Ionosphere Models for Single Frequency GNSS Receiver (단일주파수 GNSS 수신기를 위한 전리층 모델 비교)

  • Lee, Chang-Moon;Park, Kwan-Dong
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
    • /
    • /
    • pp.147-150
    • /
    • 2010
  • Ionopheric deley is the largest error sources in GNSS positining. The single frequency receiver user needs an ionospheric model like the Klobuchar model or NeQuick model to eliminate the ionospheric error. In this study we estimated VTEC(Vertical Total Electron Content) over DAEJ station using the two models in each season. We compared the results with Global Ionosphere Maps and International Reference Ionosphere model predictions. As a result, the NeQuick model was more accurate than Klobuchar model.

  • PDF

Low Latitude Plasma Blobs: A Review

  • Kim, Vitaly P.;Hegai, Valery V.
    • Journal of Astronomy and Space Sciences
    • /
    • v.33 no.1
    • /
    • pp.13-19
    • /
    • 2016
  • In recent years, there has been renewed activity in the study of local plasma density enhancements in the low latitude F region ionosphere (low latitude plasma blobs). Satellite, all-sky airglow imager, and radar measurements have identified the characteristics of these blobs, and their coupling to Equatorial Plasma Bubbles (EPBs). New information related to blobs has also been obtained from the Communication/Navigation Outage Forecasting System (C/NOFS) satellite. In this paper, we briefly review experimental, theoretical and modeling studies related to low latitude plasma blobs.

Ionospheric Storm Detection Method Using Multiple GNSS Reference Stations

  • Ahn, Jongsun;Lee, Sangwoo;Heo, Moonbeom;Son, Eunseong;Lee, Young Jae
    • Journal of Positioning, Navigation, and Timing
    • /
    • v.8 no.3
    • /
    • pp.129-138
    • /
    • 2019
  • In this work, we propose detection method for ionosphere storm that occurs locally using widespread GNSS reference stations. For ionosphere storm detection, we compare ionosphere condition with other reference stations and estimate direction of movement based on ionosphere time variation. The method use carrier phase measurement of dual frequency, for accuracy and precision of test statistics, are evaluated with multiple GNSS reference stations data.

IONOSPHERIC EFFECTS ON THE RADIO COMMUNICATION (전파통신에서의 전리층 역할)

  • PYO YOO SURN;CHO KYOUNGSEOK;LEE DONG-HUN;KIM EUNHWA
    • Publications of The Korean Astronomical Society
    • /
    • v.15 no.spc2
    • /
    • pp.21-25
    • /
    • 2000
  • The ionosphere, the atmosphere of the earth ionized by solar radiations, has been strongly varied with solar activity. The ionosphere varies with the solar cycle, the seasons, the latitudes and during any given day. Radio wave propagation through or in the ionosphere is affected by ionospheric condition so that one needs to consider its effects on operating communication systems normally. For examples, sporadic E may form at any time. It occurs at altitudes between 90 to 140 km (in the E region), and may be spread over a large area or be confined to a small region. Sometimes the sporadic E layer works as a mirror so that the communication signal does not reach the receiver. And radiation from the Sun during large solar flares causes increased ionization in the D region which results in greater absorption of HF radio waves. This phenomenon is called short wave fade-outs. If the flare is large enough, the whole of the HF spectrum can be rendered unusable for a period of time. Due to events on the Sun, sometimes the Earth's magnetic field becomes disturbed. The geomagnetic field and the ionosphere are linked in complex ways and a disturbance in the geomagnetic field can often cause a disturbance in the F region of the ionosphere. An enhancement will not usually concern the HF communicator, but the depression may cause frequencies normally used for communication to be too high with the result that the wave penetrates the ionosphere. Ionospheric storms can occur throughout the solar cycle and are related to coronal mass ejections (CMEs) and coronal holes on the Sun. Except the above mentioned phenomena, there are a lot of things to affect the radio communication. Nowadays, radio technique for probing the terrestrial ionosphere has a tendency to use satellite system such as GPS. To get more accurate information about the variation of the ionospheric electron density, a TEC measurement system is necessary so RRL will operate the system in the near future.

  • PDF