Abstract: The invention pertains to a method for recreating unavailable measurements in a GNSS system by producing at least one GNSS parameter estimate Formula (I) at a target carrier frequency (fk), the method comprising at least one of: deriving (1030), from one or more available pseudorange measurements (Pi) at respective other carrier frequencies (fi), a pseudorange estimate Formula (II) at said target carrier frequency (fk) and deriving (1040), from said one or more available pseudorange measurements (Pi) and one or more available carrier phase measurements (?i) at said respective other carrier frequencies (fi), a carrier phase estimate Formula (III) at said target carrier frequency (fk).

Abstract: The application pertains to a method for determining a phase of a target data carrier in a GNSS system, the method comprising: in an initialization phase: determining, at a first point in time, a bias term of a synthetic carrier phase function constructed to mimic a phase of the target data carrier; and in an operational phase: using said bias term determined in said initialization phase, obtaining a value of the synthetic carrier phase function, said value corresponding to a second point in time; and comparing a measured phase of the target data carrier at the second point in time to said value to assess the presence or absence of a half-cycle phase discrepancy; wherein said synthetic carrier phase function is constructed to mimic said phase of said target data carrier at points in time subsequent to said first point in time without requiring readjustment of said determined bias term.

Abstract: The invention pertains to a method for operating a GNSS receiver in the presence of spoofed signals, the GNSS receiver having a plurality of satellite signal receive chains with a low associated antenna envelope correlation coefficient, the method comprising: receiving signals from said plurality of satellite signal receive chains; obtaining (1010) relative amplitude and phase values of respective signals as provided by a pair of satellite signal receive chains from among said plurality of satellite signal receive chains; clustering (1020) said received signals on the basis of said monitored relative amplitude and phase values; and asserting (1040) a spoofing detection state when said clustering reveals a cluster of signals exhibiting similar relative amplitude and phase values over a predetermined time frame (1030). The invention also pertains to a GNSS receiver.

Abstract: The invention pertains to a method for operating a GNSS receiver in the presence of spoofed signals, the GNSS receiver having a plurality of satellite signal receive chains with a low associated antenna envelope correlation coefficient, the method comprising: receiving signals from said plurality of satellite signal receive chains; obtaining (1010) relative amplitude and phase values of respective signals as provided by a pair of satellite signal receive chains from among said plurality of satellite signal receive chains; clustering (1020) said received signals on the basis of said monitored relative amplitude and phase values; and asserting (1040) a spoofing detection state when said clustering reveals a cluster of signals exhibiting similar relative amplitude and phase values over a predetermined time frame (1030). The invention also pertains to a GNSS receiver.

Abstract: The invention pertains to a method for recreating unavailable measurements in a GNSS system by producing at least one GNSS parameter estimate Formula (I) at a target carrier frequency (fk), the method comprising at least one of: deriving (1030), from one or more available pseudorange measurements (Pi) at respective other carrier frequencies (fi), a pseudorange estimate Formula (II) at said target carrier frequency (fk) and deriving (1040), from said one or more available pseudorange measurements (Pi) and one or more available carrier phase measurements (?i) at said respective other carrier frequencies (fi), a carrier phase estimate Formula (III) at said target carrier frequency (fk).

Abstract: A correction is applied to a pseudorange measured by a satellite navigation receiver, operating on the basis of signals sampled at a sampling frequency Fs, wherein the correction is based on the measured pseudorange itself. The correction may be a correction to the discriminator value determined in the DLL, or it may be correction to the actual pseudorange as such. The correction is specific for a particular PRN code and for the parameters of the receiver. The correction is therefore implemented in the receiver as a predefined function of the measured pseudorange, to be calculated in real time, or as a look-up table of pre-defined values at least between 0 and cTs, with Ts equal to 1/Fs and c the speed of light.

Abstract: A correction is applied to a pseudorange measured by a satellite navigation receiver, operating on the basis of signals sampled at a sampling frequency Fs, wherein the correction is based on the measured pseudorange itself. The correction may be a correction to the discriminator value determined in the DLL, or it may be correction to the actual pseudorange as such. The correction is specific for a particular PRN code and for the parameters of the receiver. The correction is therefore implemented in the receiver as a predefined function of the measured pseudorange, to be calculated in real time, or as a look-up table of pre-defined values at least between 0 and cTs, with Ts equal to 1/Fs and c the speed of light.

Abstract: A method for demodulating alternate binary offset carrier signals includes at least two subcarriers, each having an in-phase and a quadrature component modulated by pseudo-random codes. The quadrature components are modulated by dataless pilot signals. The in-phase components are modulated by data signals. The method includes converting the alternate binary offset carrier signals into an intermediate frequency, band-pass filtering the converted signals and sampling the filtered signals, generating a carrier phase and carrier phase-rotating the sampled signals by the carrier phase, correlating the rotated sampled signals, and generating, for each subcarrier, pseudo-random binary codes and a subcarrier phase, which are used to correlate the rotated sampled signals.

Abstract: A method for demodulating alternate binary offset carrier signals includes at least two subcarriers, each having an in-phase and a quadrature component modulated by pseudo-random codes. The quadrature components are modulated by dataless pilot signals. The in-phase components are modulated by data signals. The method includes converting the alternate binary offset carrier signals into an intermediate frequency, band-pass filtering the converted signals and sampling the filtered signals, generating a carrier phase and carrier phase-rotating the sampled signals by the carrier phase, correlating the rotated sampled signals, and generating, for each subcarrier, pseudo-random binary codes and a subcarrier phase, which are used to correlate the rotated sampled signals.

Abstract: The present invention is related to a method and apparatus for processing a signal sent by a transmitter to a receiver, in particular for ranging applications. The signal is typically sent by a satellite, and comprises a carrier signal, modulated by at least one pseudo random noise code and a navigation signal. The method of the invention comprises a step of estimating the multipath error at each calculation of the range. The estimation is done by a multipath estimator module (23) on the basis of a predefined formula, said formula being a linear combination of said correlation values. Said formula is based on the calculation of at least four correlation values between at least four different versions of the PRN code and the PRN encoded signal sent by the transmitter. All except two of the coefficients used in the linear combination may be set to zero.

Abstract: The present invention is related to a method and apparatus for processing a signal sent by a transmitter to a receiver, in particular for ranging applications. The signal is typically sent by a satellite, and comprises a carrier signal, modulated by at least one pseudo random noise code and a navigation signal. The method of the invention comprises a step of estimating the multipath error at each calculation of the range. The estimation is done by a multipath estimator module (23) on the basis of a predefined formula, said formula being a linear combination of said correlation values. Said formula is based on the calculation of at least four correlation values between at least four different versions of the PRN code and the PRN encoded signal sent by the transmitter. All except two of the coefficients used in the linear combination may be set to zero.