A Wide Band Antenna for Multi-Constellation GNSS and Augmentation Systems

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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.

“…, n is a function of time 't', because k value varies with time. Then x (1) (t) is a time function of x (1) . Now Equation (6) can be written as…”

Section: Grey Model Gm(p Q)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Venkateswarlu¹,

Sarma²

2017

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“…Both of the LMS and RLS filters can be used in multiconstellation wide band Global Navigation Satellite Systems (GNSS) receivers. Wide band receivers are very prone to noise; hence more care should be taken while designing the multi-constellation antennas [24].…”

Section: Discussionmentioning

confidence: 99%

Estimation and Mitigation of GPS Multipath Interference Using Adaptive Filtering

Kamatham¹,

Sarma²,

Srinivas³

2011

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Abstract-Estimation and mitigation of multipath error improves the positional accuracy of GPS. The objective of this paper is to estimate the effect of multipath interference at the receiver antenna based on both code and carrier phase measurements using Code minus Carrier (CMC) technique, and suggest a suitable method to mitigate it for static applications. Different adaptive filters such as Least Mean Squares (LMS) and various Recursive Least Squares (RLS) are considered to mitigate the error. The estimated multipath error for a typical signal is 0.8 m and 2.1 m on L 1 and L 2 carriers, respectively. The results due to adaptive filtering methods are encouraging and significant reduction of error (cm level) is observed. It is found that, when compared with experimental static dual frequency GPS receiver data, LMS and RLS filters give better error minimization on L 1 and L 2 , respectively.

“…The standalone GPS is not suitable for certain critical navigation applications, such as aircraft landing. In order to meet the Required Navigation Performance (RNP) parameters: integrity, continuity, accuracy, and availability, Airport Authority of India (AAI) and Indian Space Research Organization (ISRO) developed regional Satellite Based Augmentation System (SBAS), called GPS Aided Geo Augmented Navigation (GAGAN) [1]. Ionospheric modelling is necessary for successful implementation of GAGAN system over Indian region.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Correlation Between Roti and S4 Using Gagan Data

Manga¹,

Lakshmanna²,

Sarma³

et al. 2021

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As ionosphere is one of the most prominent sources of error, ionospheric TEC and scintillation studies are necessary for improving the performance of a navigation system. In this paper, the behavior of the correlation coefficient (ρ) between Rate of TEC Index (ROTI) and amplitude scintillation index (S 4 ) over low latitude station Hyderabad (Latitude: 17.44 • (deg.) N, Longitude: 78.74 • (deg.) E) for different seasons is analyzed. Also, the analysis is extended for nearly same longitude stations like Trivandrum, Bangalore, Bhopal, Delhi, and Shimla for the higher values of total K p index for 60 days (most disturbed 5 days per month). For Trivandrum (lowest latitude station), it is observed that both S 4 and ROTI are high as compared to Bangalore, Bhopal, Delhi, and Shimla. It is found that there is a good correlation between the temporal variations of ROTI with S 4 after post sunset hours. The confidence intervals for computed correlation coefficients at 95% confidence level are also given.