Modelling of low-latitude ionosphere using modified planar fit method for GAGAN

Sarma, A. D.; Ratnam, D. Venkata; Reddy, D. Narasimha

doi:10.1049/iet-rsn.2009.0022

Cited by 50 publications

(26 citation statements)

References 6 publications

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“…In the last two decades, several grid models have been proposed to predict the TEC for GAGAN applications. Sarma et al (2009) [3] compared the performance of various grid based ionospheric time delay models for GAGAN system. Ratnam et al (2012) [4] used Spherical Harmonic Functions (SHF) to model ionosphreric time delay for GAGAN TEC network.…”

Section: Introductionmentioning

confidence: 99%

A New Technique Based on Grey Model for Forecasting of Ionospheric GPS Signal Delay Using Gagan Data

Venkateswarlu¹,

Sarma²

2017

PIER M

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Abstract-The ionospheric GPS signal delay which is a function of TEC plays a major role in the estimation positional accuracy of satellite based navigation systems and detrimental to position estimation, especially in strategic applications. Ionospheric TEC is a function of geographical location (Latitude, Longitude), time, season, etc. In this paper, we propose a system theory based Grey Model (GM(1,1)) which uses past and present data for forecasting TEC (GPS signal delay). In this model, data of nine sequential days from five stations of a GPS Aided Geo Augmented Navigation (GAGAN) system network located at different places representing different latitudes, longitudes and equatorial anomaly regions are used to forecast the 10 th day TEC values. The performance of the model is assessed by comparing the statistical parameters such as Standard Deviation (SD) and Mean Square Deviation (MSD). The forecasted results are very encouraging. For all the considered five stations, forecasting is better for post sunset time than day time. Also, the results indicate that SD and MSD values are comparatively higher for Trivandrum (near geomagnetic equator) and Ahmedabad (near the crest of the equatorial anomaly region) stations. These results indicate that the proposed model is useful for forecasting of GPS signal delay both for civil aviation and strategic applications.

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Section: Introductionmentioning

confidence: 99%

A New Technique Based on Grey Model for Forecasting of Ionospheric GPS Signal Delay Using Gagan Data

Venkateswarlu¹,

Sarma²

2017

PIER M

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“…The relation between the VTEC, STEC and the elevation-dependent mapping function at IPP is given as (Seeber 2003) (1) (Sarma, et al 2009). The hourly electric field (Ey) data were taken from (http://omniweb.gsfc.nasa.gov/form/dx1.html) in order to figure out the variations of the ionosphere enhancements caused by electric field variations.…”

Section: Data and Locationmentioning

confidence: 99%

“…Because of this, there will be a reduction in the position navigation and the timing (PTN) parameter accuracies. There are many techniques used for the estimation of TEC variations using GNSS satellites (Komjathy 1997;Schaer 1999), among which grid-based ionospheric modeling is used for the study of ionospheric modeling over the Indian region (Skone 1998;Sarma, et al 2009;Ratnam and Sarma 2012).…”

Section: Introductionmentioning

confidence: 99%

Analysis of local ionospheric variability based on SVD and MDS at low-latitude GNSS stations

Dabbakuti

Kanchumarthi

2016

Earth Planet Sp

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Investigation of ionospheric anomalies during equatorial and low latitude is of major concern for modeling and global navigation satellite system (GNSS) applications. Total electron content (TEC) varies with the ionospheric conditions, which will lead to the errors in the global positioning system (GPS) measurements. It is therefore a method that is necessary to characterize the ionospheric anomalies for satellite-based navigation systems. In this study, characterization of ionospheric variations based on the singular value decomposition (SVD) and classical multidimensional scaling (MDS) methods was studied. The yearly and daily variations are decomposed from the GPS-TEC, international reference ionosphere (IRI) 2007 and IRI 2012 models TEC over the three low-latitude GNSS stations located at Koneru Lakshmaiah University (KLU-Guntur), Hyderabad and Bangalore, respectively. From the results, it is found that there is a strong correlation between GPS-TEC and IRI models. The correlation coefficient for the first three singular values is more than 0.86. From this, it is possible to reconstruct more than 85 % of the variability contained in global GPSderived VTEC data (for year 2013) by using only the first three modes. The semiannual variation has maximum value during March-April and September-October and has minimum value during June-July. It is observed that the annual variations have maximum value in summer and minimum value in winter, and the amplitudes decrease with increasing latitude. Further, opposite latitudinal asymmetry among annual and semiannual variations for three GNSS stations is noticed. SVD and MDS methods clearly show time-varying characteristics and the absence of the winter anomaly at low-latitude GNSS stations.

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“…Those delays, in return, bring about accumulation losses during signal acquisition and integral calculation, so in this paper we introduce the compensation of TEC in the design of signal acquisition algorithms and constrain the energy loss in the decision of signal acquisition. Ionosphere Grid is a global vertical TEC network that built by GPS dual frequency receivers with the TEC precision of two to three TEC units [5] (one TEC units being 10 16 electrons/m 2 ). Based on the research of TEC compensation in signal acquisition, this paper proposes Ionosphere-Grid-aided fast acquisition algorithm and improves the acquisition performance.…”

Section: Introductionmentioning

confidence: 99%

Ionosphere-grid-aided fast acquisition algorithm of a satellite FFH telemetry signal

Chen¹,

He²,

Li³

et al. 2017

Proceedings of the 2nd Annual International Conference on Electronics, Electrical Engineering and Information Science (EEEIS 20

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Coherent Fast Frequency Hopping (FFH) spread spectrum signals effectively improve the ability to fend off forwarding jamming and interception of a satellite anti jamming communication system. However the acquisition of FFH signal is influenced by the frequency-selective ionosphere delays. The global ionosphere grid of Vertical Total Electron Content (VTEC) is used to aid the acquisition.The ionosphere delays were modeled as functions of VTEC and elevation angles, the integrals of different hops were adjusted and accumulated accordingly thus the acquisition complexity was reduced. The energy loss caused by VTEC error is calculated and the complexity reduction of this algorithm versus TEC searching algorithm is analyzed. This research is valuable to the synchronization of satellite FFH signal on different radio bands.

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Modelling of low-latitude ionosphere using modified planar fit method for GAGAN

Cited by 50 publications

References 6 publications

A New Technique Based on Grey Model for Forecasting of Ionospheric GPS Signal Delay Using Gagan Data

A New Technique Based on Grey Model for Forecasting of Ionospheric GPS Signal Delay Using Gagan Data

Analysis of local ionospheric variability based on SVD and MDS at low-latitude GNSS stations

Ionosphere-grid-aided fast acquisition algorithm of a satellite FFH telemetry signal

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