Signals processing of global navigation satellite systems (GNSS) make it possible to estimate delay due to refraction in the ionosphere, as well as the ionospheric total electronic content (TEC). Most of used the ionospheric delay estimation methods are based on processing joint measurements by code and carrier phase in two bands of signals from a navigation satellite. For these methods it is necessary to estimate the value of systematic errors associated with different signal delays in different frequency bands in the radio frequency path of the transmitter satellite and receiver navigation equipment, called differential code biases (DCB). The paper describes the features of the implementation of the method of processing only synchronous phase measurements in different frequency ranges by signals from two GLONASS satellites. The proposed method allows to exclude the influence of DCB on the error of navigation signal delay estimation due to refraction in the ionosphere. An important condition for the implementation of the method is the possibility of observing two satellites with close viewing angles relative to the receiver. The composition of the sources of uncertainty of the obtained estimates of the delay in the ionosphere and TEC is given.
Receiving and processing of global navigation satellite systems (GNSS) signals make it possible to determine the ionospheric total electronic content (TEC). Most of the TEC estimation methods used are based on processing joint measurements by code and carrier phase in two bands of signals from a navigation satellite. With such an estimate of the TEC, systematic errors arise associated with different signal delays in different frequency bands in the radio frequency path of the satellite transmitter and the navigation receiver, called differential code biases (DCB). To exclude the effect of DCB on the error in determining the slant TEC (STEC), a method for processing only simultaneous carrier-phase measurements in different frequency bands based on signals from two or three satellites is proposed. To resolve the ambiguity of carrier-phase measurements, these satellites should have a close angular position relative to the receiver.
Reception and processing of GNSS signals allows determining the full electronic content and monitoring of ionosphere parameters. Analysis of the receivers used by Russian experts to assess the Total Electron Content (TEC) shows that the measurement rate of GNSS signal parameters and the need for primary signal processing in the equipment do not allow recording fast-flowing (less than 0.2 s) processes in the ionosphere. To evaluate various ionospheric disturbances, it is proposed to record GNSS signals at a high frequency up to the initial processing stage with subsequent software processing of the recorded data. Options are proposed for constructing such a hardware-software complex for evaluating fast processes in the ionosphere. The proposed approach allows one to overcome discrepancies in the interpretation of measurements and calibration corrections for GNSS receivers.
A method for determining the values of the slant tropospheric delay of signals transmitted by the navigation satellites of the global navigation satellite systems (GNSS) is presented. The method is based on the joint processing of measurement data of meteorological parameters from the upper-air radiosonde and the propagation delays of the GNSS signals received by the on-board radiosonde receiver and ground-based stationary receiver.
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