Modeling the effects of ionospheric scintillation on GPS/Satellite‐Based Augmentation System availability

Conker, Robert S.; El-Arini, M. Bakry; Hegarty, Christopher; Hsiao, Thomas T.

doi:10.1029/2000rs002604

Cited by 246 publications

(325 citation statements)

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“…From a global view, scintillations on GNSS are more severe and frequent at low latitudes, particularly during post-sunset hours and high solar activity years, and at high latitudes scintillations also occur but less severe in magnitude (Kintner et al, 2007). Until now, the ionospheric scintillation is still one of the most challenging problems in GNSS navigation (Basu et al, 2002;Conker et al, 2003;Dehel et al, 2004;Kintner et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Climatology of GPS signal loss observed by Swarm satellites

2018

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Abstract. By using 3-year global positioning system (GPS) measurements from December 2013 to November 2016, we provide in this study a detailed survey on the climatology of the GPS signal loss of Swarm onboard receivers. Our results show that the GPS signal losses prefer to occur at both low latitudes between ±5 and ±20 • magnetic latitude (MLAT) and high latitudes above 60 • MLAT in both hemispheres. These events at all latitudes are observed mainly during equinoxes and December solstice months, while totally absent during June solstice months. At low latitudes the GPS signal losses are caused by the equatorial plasma irregularities shortly after sunset, and at high latitude they are also highly related to the large density gradients associated with ionospheric irregularities. Additionally, the highlatitude events are more often observed in the Southern Hemisphere, occurring mainly at the cusp region and along nightside auroral latitudes. The signal losses mainly happen for those GPS rays with elevation angles less than 20 • , and more commonly occur when the line of sight between GPS and Swarm satellites is aligned with the shell structure of plasma irregularities. Our results also confirm that the capability of the Swarm receiver has been improved after the bandwidth of the phase-locked loop (PLL) widened, but the updates cannot radically avoid the interruption in tracking GPS satellites caused by the ionospheric plasma irregularities. Additionally, after the PLL bandwidth increased larger than 0.5 Hz, some unexpected signal losses are observed even at middle latitudes, which are not related to the ionospheric plasma irregularities. Our results suggest that rather than 1.0 Hz, a PLL bandwidth of 0.5 Hz is a more suitable value for the Swarm receiver.

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Section: Introductionmentioning

confidence: 99%

Climatology of GPS signal loss observed by Swarm satellites

2018

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“…This is not surprising since it is well known that tolerance to phase scintillation increases with increasing carrier loop bandwidth [Morrissey et al, 2000;Knight and Finn, 1998;Conker et al, 2000]. The L1 carrier loop bandwidths of the EMAGR and GSV4004 are 15 and 10 Hz, respectively, as compared to the 3 Hz WRS L1 carrier loop bandwidth.…”

Section: Emagr and Gsv4004 Resultsmentioning

confidence: 81%

“…The L1 carrier loop bandwidths of the EMAGR and GSV4004 are 15 and 10 Hz, respectively, as compared to the 3 Hz WRS L1 carrier loop bandwidth. The latter bandwidth, though chosen primar- ily for RFI reduction purposes, provides a good compromise between tolerance to phase scintillation and tolerance to amplitude scintillation, which decreases with increasing carrier loop bandwidth [Morrissey et al, 2000;Knight and Finn, 1998;Conker et al, 2000]. 7. Estimation of Phase Scintillation at L1 (S f f f f f )from L2 Carrier Phase Error Standard Deviation [24] In a related effort [Shallberg, 2001] an analysis was performed of the correlation between phase scintillation strength s f and L2 carrier phase standard deviation for WAAS measurement data.…”

Section: Emagr and Gsv4004 Resultsmentioning

confidence: 99%

“…In theory [Knight and Finn, 1998;Conker et al, 2000], the logarithm of a phase scintillation power spectral density (PSD) function is related to the logarithm of frequency by a straight line. However, in the absence of any low-pass filtering, the PSDs associated with the above data began leveling off around 2-3 Hz owing to the more dominant receiver noise floor, a typical observation at the GPS L1 frequency.…”

Section: Phase Scintillation Waveform Generationmentioning

confidence: 99%

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GPS receiver performance characterization under realistic ionospheric phase scintillation environments

Morrissey

Shallberg

Dierendonck³

et al. 2004

Radio Science

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It is well known that ionospheric scintillation has the potential to affect all types of GPS receivers, even dual‐frequency military precise‐positioning service versions. In a previous effort the degree of degradation to Wide Area Augmentation System (WAAS) operation caused by scintillation, on the basis of simulated data input to an actual WAAS reference receiver under carefully controlled laboratory conditions at Space and Naval Warfare Systems Center, was analyzed and reported [Morrissey et al., 2000]. This degradation is manifested in increased errors for carrier phase and code range measurements and in a higher probability of loss of GPS signal track. However, the results supported the assessment that scintillation should not be a problem for WAAS receivers in the conterminous United States, except perhaps during the very rare occurrence of a “severe geomagnetic storm.” The previous work was briefed in a number of fora, and a detailed report was widely distributed throughout the ionospheric community along with a request for identification of any “gaps” in the results that could be addressed with further testing. From the feedback received, the following tests were conducted: (1) tests with long‐duration deep amplitude nulls, corresponding to the GPS signal moving with the ionospheric disturbance; (2) tests with phase scintillation waveforms derived from 50 Hz ionospheric scintillation monitor (ISM) data previously collected by the U.S. Air Force (Philips Laboratory) at Antofagosta, Chile; (3) tests of a modified military single‐frequency receiver (Enhanced Miniaturized Airborne GPS Receiver (EMAGR)) side‐by‐side with the WAAS receiver, with emphasis on maintaining lock at L1; and (4) tests at values of input carrier‐to‐noise ratio (CNR) lower (i.e., down to 36 dB Hz) than those used in the original tests. The tests with deep amplitude nulls were reported by Morrissey et al. [2002], and the tests with realistic input phase scintillation waveforms were reported at the Ionospheric Effects Symposium (IES) 2002. The current paper is based upon the IES 2002 results as modified by recent testing. Both these amplitude and phase results include EMAGR and low CNR performance.

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“…The ionospheric scintillation, caused by irregularities in the density of electrons present in the ionosphere, can weaken the signal received by the GPS receiver, causing degradation of positioning or even signal loss [3]. The main indicative to investigate the ionospheric scintillation impact in GPS satellite signals quality is the S4 index.…”

Section: Methodsmentioning

confidence: 99%

Non-decimated Wavelet Transform for a Shift-invariant Analysis

Brassarote

Souza

2018

Tend. Mat. Apl. Comput.

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ABSTRACT. Due to the ability of time-frequency location, the wavelet transform has been applied in several areas of research involving signal analysis and processing, often replacing the conventional Fourier transform. The discrete wavelet transform has great application potential, being an important tool in signal compression, signal and image processing, smoothing and de-noising data. It also presents advantages over the continuous version because of its easy implementation, good computational performance and perfect reconstruction of the signal upon inversion. Nevertheless, the downsampling required in the computation of the discrete wavelet transform makes it shift variant and not appropriated to some applications, such as for signals or time series analysis. On the other hand, the Non-Decimated Discrete Wavelet Transform is shiftinvariant because it eliminates the downsampling and, consequently, is more appropriate for identifying both stationary and non-stationary behaviors in signals. However, the non-decimated wavelet transform has been underused in the literature. This paper intends to show the advantages of using the non-decimated wavelet transform in signal analysis. The main theoretical and practical aspects of the multi-scale analysis of time series from non-decimated wavelets in terms of its formulation using the same pyramidal algorithm of the decimated wavelet transform was presented. Finally, applications with a simulated and real time series compare the performance of the decimated and non-decimated wavelet transform, demonstrating the superiority of non-decimated one, mainly due to the shift-invariant analysis, patterns detection and more perfect reconstruction of a signal.

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Modeling the effects of ionospheric scintillation on GPS/Satellite‐Based Augmentation System availability

Cited by 246 publications

References 12 publications

Climatology of GPS signal loss observed by Swarm satellites

Climatology of GPS signal loss observed by Swarm satellites

GPS receiver performance characterization under realistic ionospheric phase scintillation environments

Non-decimated Wavelet Transform for a Shift-invariant Analysis

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