Abstract: A computer-implemented method is for detecting Global Navigation Satellite System (GNSS) signal spoofing. The method includes storing sample sequences of the predictable part and of the unpredictable part of a GNSS signal at a GNSS receiver. The predictable part includes predictable bits and the unpredictable part includes unpredictable bits. The value of the unpredictable bits from which the unpredictable sample sequences are extracted is verified. A first and a second partial correlation between the unpredictable, respectively predictable, sample sequences and a locally stored GNSS signal replica are computed. A predefined metric from the complex valued partial correlations is calculated. The predefined metric is compared with a predefined threshold value. In a zero-delay replay attack, the spoofer estimates the unpredictable bits introduced by a GNSS authentication protocol and introduces distortion into the signal.

Abstract: A method of processing positioning signal constituted by a superposition of individual signals generated by a plurality of emitters, in particular satellite emitters, comprising:—a first step of coarse acquisition of said individual signals, comprising correlation of the received positioning signal with locally generated replicas of said individual signals;—a step of identifying spurious correlation peaks induced by interferences; and—a step of estimating the code delays and the carrier frequency shifts of the acquired individual signals which are not affected by said interferences. According to preferred embodiments of the invention, the method can also comprise:—a refining step of determining more accurate estimates of said code delays and carrier frequency shifts; and—a step of interference cancellation. The method of the invention is particularly suitable to indoor positioning applications.

Abstract: A method of processing positioning signal constituted by a superposition of individual signals generated by a plurality of emitters, in particular satellite emitters, comprising:—a first step of coarse acquisition of said individual signals, comprising correlation of the received positioning signal with locally generated replicas of said individual signals;—a step of identifying spurious correlation peaks induced by interferences; and—a step of estimating the code delays and the carrier frequency shifts of the acquired individual signals which are not affected by said interferences. According to preferred embodiments of the invention, the method can also comprise:—a refining step of determining more accurate estimates of said code delays and carrier frequency shifts; and—a step of interference cancellation. The method of the invention is particularly suitable to indoor positioning applications.

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.