Spoofing detection system for a satellite positioning system

A satellite positioning system receiver system capable of detecting a change from receiving (i) satellite information signals transmitted from a transmitter aboard satellite vehicles which form, in part, a satellite based global positioning system, where each of said satellite information signals consists of a carrier signal having coded satellite-specific information, therewith, from which (a) the estimated position of said satellite vehicles may be determined at selected moments in time, (b) the range between a satellite information signal receiver system antenna and selected ones of said satellite vehicles may be estimated, and (c) the position of the satellite information signal receiver system antenna may be estimated, and (ii) reception of one or more satellite information signals transmitted from a spoofing signal transmitter and which contain erroneous satellite-specific information therewith, said satellite positioning system receiver system comprising:

• signal receiver system means for tracking said satellite information signals, said signal receiver system means including,
• first and second antennae, separated by a known separation distance, for separately receiving said satellite information signals and producing first and second electrical signals, respectively, in response to said received signals;
• means for deriving first satellite-specific information from said first electrical signal for each received satellite information signal, and for deriving second satellite-specific information from said second electrical for each received satellite information signal;
• means for deriving transmitter-specific discriminant values, where each of said transmitter-specific discriminant values is derived from said first and second satellite-specific information associated with a single satellite information signal transmitted from a single transmitter, and where each of said transmitter-specific discriminant values is related to a transmitter-specific pointing angle, where said pointing angle is the angle between (i) a vector from said first to said second antenna, and (ii) a vector from said first antenna to one of said transmitters
• analyzing processor means for analyzing said transmitter-specific discriminant values and determining a statistical value of said transmitter-specific discriminant values;
• and
• means for comparing said statistical value with a selected detection threshold value where said comparison is indicative of said statistical value deviating from a selected norm of operation consistent with the behavior of satellite information signals transmitted from satellite vehicle transmitters, thereby providing an indication of receiving satellite information signals from a spoofing signal transmitter.

A method for detecting a satellite positioning system signal receiver system receiving satellite information signals transmitted from a spoofing signal transmitter and which contain erroneous satellite-specific information therewith, as compared to those satellite information signals transmitted from a transmitter aboard satellite vehicles which form, in part, a satellite based global positioning system, where each of said satellite information signals consists of a carrier signal having coded satellite-specific information, therewith, from which (a) the estimated position of said satellite vehicles may be determined at selected moments in time, (b) the range between a satellite information signal receiver system antenna and selected ones of said satellite vehicles may be estimated, and (c) the position of the satellite information signal receiver system antenna may be estimated, said method comprising the steps of:

• separately receiving said satellite information signals through first and second antennae, separated by a known separation distance, and producing first and second electrical signals, respectively, in response to said received satellite information signals;
• deriving first transmitter-specific information from said first electrical signal for each received satellite information signal;
• deriving second transmitter-specific information from said second electrical for each received satellite information signal;
• deriving transmitter-specific discriminant values, where each of said transmitter-specific discriminant values is derived from said first and second transmitter-specific information associated with a single satellite information signal transmitted from a single transmitter, and where each of said transmitter-specific discriminant values is related to a transmitter-specific pointing angle, where said pointing angle is the angle between (i) a vector from said first to said second antenna, and (ii) a vector from said first antenna to one of said transmitters;
• and
• selectively comparing said transmitter-specific discriminant values with a selected norm of operation consistent with satellite information signals transmitted from said satellite vehicles which form, in-part, said satellite positioning system.

A method for detecting a satellite positioning system signal receiver system receiving satellite information signals transmitted from a spoofing signal transmitter and which contain erroneous satellite-specific information therewith, as compared to those satellite information signals transmitted from a transmitter aboard satellite vehicles which form, in part, a satellite based global positioning system, where each of said satellite information signals consists of a carrier signal having coded satellite-specific information, therewith, from which (a) the estimated position of said satellite vehicles may be determined at selected moments in time, (b) the range between a satellite information signal receiver system antenna and selected ones of said satellite vehicles may be estimated, and (c) the position of the satellite information signal receiver system antenna may be estimated, said method comprising the steps of:

• separately receiving said satellite information signals through first and second antennae, separated by a known separation distance, and producing first and second electrical signals, respectively, in response to said received satellite information signals;
• deriving first transmitter-specific information from said first electrical signal for each received satellite information signal;
• deriving second transmitter-specific information from said second electrical for each received satellite information signal;
• deriving, from said first and second transmitter-specific information, the estimated geocentric position of said first and second antennae and a line-of-sight vector matrix representative of the vectors between said first antenna and each of said satellite vehicles associated with said received satellite information signals by said first antenna;
• determining the carrier phase difference between each satellite information signal received by both said first and second antennae;
• determining the time rate of change of a first vector, where said first vector is representative of a vector between said first and second antennae;
• calculating the rate of change of said first vector;
• and
• selectively comparing said rate of change of said first vector to a selected detection threshold value where said comparison is indicative of said statistical value deviating from a selected norm of operation consistent with the behavior of satellite information signals transmitted from satellite vehicle transmitters, thereby providing an indication of receiving satellite information signals from a spoofing signal transmitter .