Characteristics of L-band (1.5GHz) and VHF (244MHz) amplitude scintillations recorded at Kolkata during 1996–2006 and development of models for the occurrence probability of scintillations using neural network

Das, Arijit; Gupta, Arjun; Ray, S.

doi:10.1016/j.jastp.2010.03.010

Cited by 18 publications

(6 citation statements)

References 51 publications

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“…Correlation between the fading rates of VHF scintillations and GPS S 4 has been studied by Das et al []. The scale size of irregularities causing GPS L band scintillations are of the order of 300–400 m. It has been observed from GPS scintillation records at Calcutta and Siliguri that the durations of scintillation patches on different satellite links recorded from Calcutta and Siliguri are often 25–30 min, which in turn indicates a spatial zonal extent of the irregularity cloud of 300–400 km, assuming a nominal zonal drift velocity of 200 m/s [ Bhattacharyya et al , , ].…”

Section: Discussionmentioning

confidence: 99%

Relation of decorrelated transionospheric GPS signal fluctuations from two stations in the northern anomaly crest region with equatorial ionospheric dynamics

Paul

2017

Radio Sci.

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The ionosphere around the northern crest of the equatorial ionization anomaly (EIA) and beyond exhibits rapid temporal as well as spatial development of ionization density irregularities during postsunset hours. A GPS campaign was conducted during September 2012 and April 2013 from the Institute of Radio Physics and Electronics, Calcutta (22.58°N, 88.38°E geographic; magnetic dip: 32°N), and North Bengal University (NBU), Siliguri (26.72°N, 88.39°E geographic, magnetic dip: 39.49°N) in India in order to assess and quantify differences, if any, in the nature of carrier to noise ratio (C/N0) fluctuations observed on the same satellite link around the same time interval from these stations. Significant decorrelation of the received signals was found when tracking the same satellite vehicle (SV) link from these stations during periods of scintillations. Low values of correlation coefficient of C/N0 at L1 frequency recorded on the same SV link at these two stations were found to correspond with high irregularity characteristic velocities. North‐south spatial displacement rates of the impact of ionospheric irregularities were calculated based on coordinated GPS observations which followed an increasing trend with irregularity characteristic velocities measured at VHF. Values of characteristic velocities in excess of 36 m/s were also found to result in large receiver position deviations ~3.5–4.0 m during periods of scintillations. Information related to time lag associated with occurrence of scintillations on the same SV link observed from two stations could be useful for improving performance of transionospheric satellite‐based position determination techniques.

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Section: Discussionmentioning

confidence: 99%

Relation of decorrelated transionospheric GPS signal fluctuations from two stations in the northern anomaly crest region with equatorial ionospheric dynamics

Paul

2017

Radio Sci.

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“…Significant decorrelation in received transionospheric satellite signal phase from C/NOFS has been reported at VHF and UHF from Ascension Island [ van de Kamp et al, ]. Correlation between the fading rates of VHF scintillations and GPS S 4 has been attempted earlier [ Das et al, ]. GPS PDOP, which combines values of horizontal as well as vertical positioning accuracies, provides an estimate of the level of integrity of position determination to the user.…”

Section: Discussionmentioning

confidence: 99%

Effects of transionospheric signal decorrelation on Global Navigation Satellite Systems (GNSS) performance studied from irregularity dynamics around the northern crest of the EIA

2014

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Transionospheric satellite navigation links operate primarily at L band and are frequently subject to severe degradation of performances arising out of ionospheric irregularities. Various characteristic features of equatorial ionospheric irregularity bubbles like the drift velocity, characteristic velocity, decorrelation time, and decorrelation distance can be determined using spaced aerial measurements at VHF. These parameters measured at VHF from a station Calcutta situated near the northern crest of the Equatorial Ionization Anomaly (EIA) in the geophysically sensitive Indian longitude sector have been correlated with L band scintillation indices and GPS position accuracy parameters for identifying possible proxies to L band scintillations. Good correspondences have been observed between decorrelation times and distances at VHF with GPS S 4 and Position Dilution of Precision during periods of GPS scintillations (S 4

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“…Hence, the signal outages from this location form an important benchmark for the international Space Weather program. Ray and DasGupta (2007) and Das et al (2010) had observed the occurrence of post sunset GPS L band scintillation from Calcutta to be maximum during the equinoctial periods. This GNSS receiver is able to track and log data from GPS, GLONASS, and Galileo, as well as different Satellite-based Augmentation System satellites at corresponding transmission frequencies.…”

Section: Methodsmentioning

confidence: 99%

Interfrequency Performance Characterizations of GPS During Signal Outages From an Anomaly Crest Location

et al. 2019

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Introduction of new navigation signals L2C (1227.60 MHz) and L5 (1176.45 MHz) to the existing GPS (Global Positioning System) spectrum, under the modernization program of GPS offers the improvement of position accuracy. The present study aims to understand the relative robustness of the L2C and L5 signals compared to legacy L1 C/A signal during periods of scintillations in terms of durations of cycle slips encountered from an anomaly crest location, Calcutta (22.58°N, 88.38°E geographic; magnetic dip 32°N). The data analyzed in this study were recorded during the vernal equinox of 2014 (February–April), a period of high solar activity of cycle 24. Results obtained from the comparative analyses, which are perhaps one of the first from the Indian longitude sector, indicate GPS L5 to be more robust than L1 C/A and L2C in terms of occurrence and duration of cycle slips under adverse ionospheric conditions. Furthermore, loss‐of‐lock events of duration greater than 6 s are found to be more frequent for S4 ≥ 0.6. It is found that frequency sensitivity of the GPS spectrum, in terms of occurrence of cycle slips and loss of locks are in conformity with earlier results from the equatorial region but are different from the high latitudes with respect to local time of occurrence and geomagnetic activity.

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Characteristics of L-band (1.5GHz) and VHF (244MHz) amplitude scintillations recorded at Kolkata during 1996–2006 and development of models for the occurrence probability of scintillations using neural network

Cited by 18 publications

References 51 publications

Relation of decorrelated transionospheric GPS signal fluctuations from two stations in the northern anomaly crest region with equatorial ionospheric dynamics

Relation of decorrelated transionospheric GPS signal fluctuations from two stations in the northern anomaly crest region with equatorial ionospheric dynamics

Effects of transionospheric signal decorrelation on Global Navigation Satellite Systems (GNSS) performance studied from irregularity dynamics around the northern crest of the EIA

Interfrequency Performance Characterizations of GPS During Signal Outages From an Anomaly Crest Location

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