Publication Date:
2019-02-01
Description:
Ionospheric scintillations are caused by timevarying electron density irregularities in the ionosphere, occurring more often at equatorial and high latitudes. This paper focuses exclusively on experiments undertaken in Europe, at geographic latitudes between ~50°N and ~80°N,
where a network of GPS receivers capable of monitoring Total Electron Content and ionospheric scintillation parameters
was deployed. The widely used ionospheric scintillation indices S4 and бφ represent a practical measure of the intensity of amplitude and phase scintillation affecting
GNSS receivers. However, they do not provide sufficient information regarding the actual tracking errors that degrade GNSS receiver performance. Suitable receiver tracking models, sensitive to ionospheric scintillation, allow the computation
of the variance of the output error of the receiver PLL (Phase Locked Loop) and DLL (Delay Locked Loop), which expresses the quality of the range measurements used by the
receiver to calculate user position. The ability of such models of incorporating phase and amplitude scintillation effects into the variance of these tracking errors underpins our proposed method of applying relative weights to measurements from
different satellites. That gives the least squares stochastic model used for position computation a more realistic representation,
vis-a-vis the otherwise ‘equal weights’ model.
For pseudorange processing, relative weights were computed, so that a ‘scintillation-mitigated’ solution could be performed and compared to the (non-mitigated) ‘equal
weights’ solution. An improvement between 17 and 38% in height accuracy was achieved when an epoch by epoch differential solution was computed over baselines ranging from
1 to 750 km. The method was then compared with alternative approaches that can be used to improve the least squares stochastic model such as weighting according to satellite elevation angle and by the inverse of the square of the standard deviation of the code/carrier divergence (sigma CCDiv). The influence of multipath effects on the proposed mitigation approach is also discussed. With the use of high rate scintillation data in addition to the scintillation indices a carrier phase based mitigated solution was also implemented and
compared with the conventional solution. During a period of occurrence of high phase scintillation it was observed that problems related to ambiguity resolution can be reduced by the use of the proposed mitigated solution.
Description:
Published
Description:
953-966
Description:
1.7. Osservazioni di alta e media atmosfera
Description:
3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
Description:
JCR Journal
Description:
reserved
Keywords:
Global navigation satellites system
;
Global positioning system
;
Ionospheric scintillation
;
Receiver tracking models
;
Mitigation
;
Stochastic model
;
01. Atmosphere::01.02. Ionosphere::01.02.07. Scintillations
;
05. General::05.07. Space and Planetary sciences::05.07.01. Solar-terrestrial interaction
;
05. General::05.07. Space and Planetary sciences::05.07.02. Space weather
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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