V. V. Demyanov

The total failures of GPS functioning caused by the powerful solar radio burst on December 13, 2006

We investigated failures in the GPS performance produced by extremely dense solar radio burst fluxes associated with the intense (X3.4 in GOES classification) solar flare and Halo CME recorded by SOHO/LASCO on December 13, 2006. According to substantial experimental evidence, high-precision GPS positioning on the entire sunlit side of the Earth was partially disrupted for more than 12–15 min; the high level of GPS slips resulted from the wideband solar radio noise emission. Our results are in agreement with the data obtained recently for the extreme solar radio burst on December 6, 2006, and provide a sound basis for revising the role of space weather factors in the functioning of state-of-the-art satellite systems and for taking a more thorough account of these factors in their development and operation.

Malfunction of satellite navigation systems GPS and GLONASS caused by powerful radio emission of the Sun during solar flares on December 6 and 13, 2006, and October 28, 2003

Poor quality of functioning of GPS during solar flares on December 6 and 13, 2006 is analyzed in this paper. These flares were accompanied by extremely high (unexampled) level of the solar radio emission flux. A comparison is made of these events with the solar flare on October 28, 2003. Statistically reliable experimental evidence is obtained that GPS positioning was partially paralyzed on the sunlit side of the Earth during the strongest bursts of solar radio emission. The obtained results give a serious ground to revise the role played by space weather factors in operation of modern satellite systems and to take these factors into account more carefully, when such systems are designed and exploited.

Effects of Solar Radio Emission and Ionospheric Irregularities on GPS/GLONASS Performance

During the period of 2001-2010, several strong geomagnetic storms and direct solar radio emission interference deteriorated serious GPS performance. The L-band solar radio emission has recently been regarded as a potential threat to stable GPS and GLONASS performance. However, the threat has not been completely investigated or assessed so far. Furthermore, ionization anomaly at low latitudes along with the effect of the equatorial plasma “bubbles” increase the possibility of fading for transionospheric signals, especially during geomagnetic storms. Instabilities of ionospheric plasma on the “walls” of a bubble with electron density lower than the background value are also characterized by sharp gradients of electron density. For example, the walls of bubbles can be a source of ionospheric scintillations as well. There‐ fore, the spatial orientation of plasma bubble plays a decisive role in strengthening and weakening the amplitude and phase scintillations of satellite vehicle (SV) signals.

Experimental observations of carrier phase acceleration in conditions of polar ionosphere

The paper presents a comparative analysis of the quality of measuring the phase carrier of signals from GLONASS and GPS navigation satellites and spectrum of small-scale irregularities of electron density in conditions of a nonstationary and inhomogeneous polar ionosphere. It is shown that small-scale irregularities of the electron density in the ionosphere can lead to a substantial nonstationary increase in the acceleration of the phase carrier of both GPS and GLONASS by a factor of 1.3–2.5 from the background level.

Detecting the small-scale ionospheric irregularities based on GNSS data

Small-scale ionospheric disturbances can bring additional information about earthquakes and tsunami parameters. On the other hand such weak disturbances hardly can be detected by GNSS-TEC measurements. Being using of S4 and σφ indices we can count on reliable detecting of such events. However both of these indices do not have enough sensitivity too. We suppose that the second-order derivative of the GNSS signal phase is a high-sensitive parameter for the small-scale ionospheric disturbances detection. This report devotes to the problem of how to utilize the second-order derivative of the GNSS-signal phase as a sensitive mean to detect the weak small-scale ionospheric disturbances.

Controlling current conditions of signal propagation of navigation satellites

We suggest using the S4 scintillation index to control the current radiowave propagation condition and radio navigation parameter measurement quality by signals from individual GPS satellites. We corroborate the possibility to use the S4 index for the above purposes by example of simultaneous observations of navigation-temporal positioning errors via applying users GPS/ GLONASS MRK-19L navigation equipment and current geomagnetic conditions during the 2004 November 9 powerful magnetic storm.

THE METHOD OF REAL-TIME CONTROL OF POSITIONING QUALITY FOR THE TRANSPORTATION APPLICATIONS

A new method of real-time GPS/WAAS user positioning quality control for transportation applications is considered. Current quality of positioning is defined through the GPS/WAAS user’s required navigation parameters (RNP) such as positioning accuracy and positioning availability taking in account the current Positioning Delusion of Precision (PDOP). The method is based on real-time assessment of the RNP achievement total probability for the concrete GPS/WAAS user within WAAS coverage zone. The method allows detecting sudden positioning quality deterioration for the concrete RNP of aviation users and can be effectively used for some transportation applications which have strong RNP. Especially, the method can be recommended for transportation applications such as aviation landing systems and automatic railroad traffic control.

Deterioration in the Accuracy of GPS System Positioning due to the Effect of Ionospheric Bubbles

The state of the ionosphere affects the operational stability of satellite radio navigation systems. The dense network of GEONET GPS sites on the territory of Japan allows to conduct a thorough investigation of the stability of system operation at mid-latitudes in different heliogeophysical conditions. This paper considers deterioration in the accuracy of GPS system positioning due to the effect of a large-scale ionospheric disturbance (an ionospheric bubble) over Japan on February 12, 2000.