Multifrequency studies of equatorial ionospheric scintillations at Ootacamund

Rastogi, R. G.; Koparkar, P. V.; Chandra, H.; Deshpande, M. R.

doi:10.1016/0021-9169(90)90116-5

Cited by 6 publications

(3 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…S 4 < 0.6. Instead for S 4 > 0.6 n decreases monotonically, approaching a value of zero for saturated scintillations (strong scintillations) (Rastogi et al, 1990).…”

Section: Which Is the Frequencymentioning

confidence: 95%

A different approach to the analysis of GPS scintillation data

Forte

Radicella

Ezquer

2009

Annals of Geophysics

View full text Add to dashboard Cite

Amplitude scintillation data from GPS were analyzed. The objective is to estimate the impact of ionospheric scintillations at Satellite Based Augmentation Systems Ranging and Integrity Monitoring Station (SBAS RIMS) level and at GPS user level. For this purpose, a new approach to the problem was considered. Data were studied from the point of view of the impact of scintillations on the calculation of VTEC at pierce points and ionospheric grid points. An ionospheric grid of 5°× 5°surface squares was assumed. From geometrical considerations and taking into account the basic principle to compute VTEC at grid points, with the data analyzed it is shown that scintillations very seldom affect the calculation of a grid point VTEC. Data from all the RIMS and for the entire GPS satellites network must be analyzed simultaneously to describe a realistic scenario for the impact of scintillations on SBAS. Finally, GPS scintillation data were analyzed at user level: service availability problems were encountered.

show abstract

“…S 4 < 0.6. Instead for S 4 > 0.6 n decreases monotonically, approaching a value of zero for saturated scintillations (strong scintillations) (Rastogi et al, 1990).…”

Section: Which Is the Frequencymentioning

confidence: 95%

A different approach to the analysis of GPS scintillation data

Forte

Radicella

Ezquer

2009

Annals of Geophysics

View full text Add to dashboard Cite

show abstract

“…The scaling on the phase was accomplished by keeping the ratio between different wavelengths considered. On the other hand, the scaling on the intensity was accomplished by assuming a dependence on the wavelength of the tye S 4 ∝ f −1.5 , which is a reasonable assumption for typical low latitudes conditions and low scintillation levels [ Yeh and Liu , 1982; Rastogi et al , 1990]. The particular scaling adopted to perturb both the intensity and phase of nominal GNSS signals was based on a conservative assumption.…”

Section: The Simulation Scenariosmentioning

confidence: 99%

Analysis of the PLL phase error in presence of simulated ionospheric scintillation events

Forte

2012

Radio Science

View full text Add to dashboard Cite

[1] The functioning of standard phase locked loops (PLL), including those used to track radio signals from Global Navigation Satellite Systems (GNSS), is based on a linear approximation which holds in presence of small phase errors. Such an approximation represents a reasonable assumption in most of the propagation channels. However, in presence of a fading channel the phase error may become large, making the linear approximation no longer valid. The PLL is then expected to operate in a non-linear regime. As PLLs are generally designed and expected to operate in their linear regime, whenever the non-linear regime comes into play, they will experience a serious limitation in their capability to track the corresponding signals. The phase error and the performance of a typical PLL embedded into a commercial multiconstellation GNSS receiver were analyzed in presence of simulated ionospheric scintillation. Large phase errors occurred during scintillation-induced signal fluctuations although cycle slips only occurred during the signal re-acquisition after a loss of lock. Losses of lock occurred whenever the signal faded below the minimum C/N 0 threshold allowed for tracking. The simulations were performed for different signals (GPS L1C/A, GPS L2C, GPS L5 and Galileo L1). L5 and L2C proved to be weaker than L1. It appeared evident that the conditions driving the PLL phase error in the specific case of GPS receivers in presence of scintillation-induced signal perturbations need to be evaluated in terms of the combination of the minimum C/N 0 tracking threshold, lock detector thresholds, possible cycle slips in the tracking PLL and accuracy of the observables (i.e. the error propagation onto the observables stage).Citation: Forte, B. (2012), Analysis of the PLL phase error in presence of simulated ionospheric scintillation events, Radio Sci., 47, RS3006,

show abstract

“…Some of the most intense postsunset ionospheric scintillations are encountered at locations around the northern crest of the Equatorial Ionization Anomaly (EIA) in the Indian longitude sector, and the occurrence morphology depends on season, longitude, solar cycle, and magnetic activity, and exhibits a high degree of variability from one night to the next [ Aarons , ]. Extensive observations of scintillations have been reported from the geophysically sensitive Indian longitude sector involving Applications Technology Satellite‐6 (ATS‐6) and All India Coordinated Programme of Ionospheric and Thermospheric Studies (AICPITS) [ Chandra et al, , ; Rastogi et al, , ; Somayajulu et al, ; Dabas and Reddy , ; Kumar et al, ]. Stations like Calcutta (latitude: 22.58°N longitude: 88.38°E geographic; magnetic dip: 32°N) experience intense, often saturated, scintillations at VHF and L band on a significant proportion of nights during the equinoxes.…”

Section: Introductionmentioning

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

View full text Add to dashboard Cite

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

show abstract

Multifrequency studies of equatorial ionospheric scintillations at Ootacamund

Cited by 6 publications

References 17 publications

A different approach to the analysis of GPS scintillation data

A different approach to the analysis of GPS scintillation data

Analysis of the PLL phase error in presence of simulated ionospheric scintillation events

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

Contact Info

Product

Resources

About