Abstract: Methods and systems that can detect GNSS spoofing attacks and that do not require explicit or implicit knowledge of exact position or attitude and that provide hypothesis test statistics, threshold values, and probabilities of false alarm and missed detection.

Abstract: A system and method of continuous carrier wave reconstruction includes a radio navigation receiver that includes one or more processors, memory coupled to the one or more processors, and an input for receiving a signal from a transmitter. The signal has a phase. The one or more processors are configured to obtain phase lock on the received signal, extract first phase information from the received signal, detect a loss in phase lock on the received signal, and extrapolate second phase information while phase lock is lost using a model of the phase. In some embodiments, the one or more processors are further configured to reconstruct the carrier signal based on the first and second phase information. In some embodiments, the one or more processors are further configured to scale the first and second phase information from a first nominal frequency of the received signal to a different second nominal frequency.

Abstract: Position, navigation and/or timing (PNT) solutions may be provided with levels of precision that have previously and conventionally been associated with carrier phase differential GPS (CDGPS) techniques that employ a fixed terrestrial reference station or with GPS PPP techniques that employ fixed terrestrial stations and corrections distribution networks of generally limited terrestrial coverage. Using techniques described herein, high-precision PNT solutions may be provided without resort to a generally proximate, terrestrial ground station having a fixed and precisely known position. Instead, techniques described herein utilize a carrier phase model and measurements from plural satellites (typically 4 or more) wherein at least one is a low earth orbiting (LEO) satellite. For an Iridium LEO solution, particular techniques are described that allow extraction of an Iridium carrier phase observables, notwithstanding TDMA gaps and random phase rotations and biases inherent in the transmitted signals.

Abstract: Position, navigation and/or timing (PNT) solutions may be provided with levels of precision that have previously and conventionally been associated with carrier phase differential GPS (CDGPS) techniques that employ a fixed terrestrial reference station or with GPS PPP techniques that employ fixed terrestrial stations and corrections distribution networks of generally limited terrestrial coverage. Using techniques described herein, high-precision PNT solutions may be provided without resort to a generally proximate, terrestrial ground station having a fixed and precisely known position. Instead, techniques described herein utilize a carrier phase model and measurements from plural satellites (typically 4 or more) wherein at least one is a low earth orbiting (LEO) satellite. For an Iridium LEO solution, particular techniques are described that allow extraction of an Iridium carrier phase observables, notwithstanding TDMA gaps and random phase rotations and biases inherent in the transmitted signals.

Abstract: Methods and systems that can detect GNSS spoofing attacks and that do not require explicit or implicit knowledge of exact position or attitude and that provide hypothesis test statistics, threshold values, and probabilities of false alarm and missed detection.

Abstract: A system and method of continuous carrier wave reconstruction includes a radio navigation receiver that includes one or more processors, memory coupled to the one or more processors, and an input for receiving a signal from a transmitter. The signal has a phase. The one or more processors are configured to obtain phase lock on the received signal, extract first phase information from the received signal, detect a loss in phase lock on the received signal, and extrapolate second phase information while phase lock is lost using a model of the phase. In some embodiments, the one or more processors are further configured to reconstruct the carrier signal based on the first and second phase information. In some embodiments, the one or more processors are further configured to scale the first and second phase information from a first nominal frequency of the received signal to a different second nominal frequency.

Abstract: A system and method for detecting spoofing of signals by processing intermittent bursts of encrypted Global Navigation Satellite System (GNSS) signals in order to determine whether unencrypted signals are being spoofed. The system and method can allow a specially equipped GNSS receiver to detect sophisticated spoofing that cannot he detected using receiver antonomous integrity monitoring techniques. The system and method do not require changes to the signal structure of encrypted civilian GNSS signals, but instead use a short segment of an encrypted signal that is broadcast by the same GNSS spacecraft which broadcast the unencrypted signal of interest.

Abstract: A system and method for detecting spoofing of signals by processing intermittent bursts of encrypted Global Navigation Satellite System (GNSS) signals in order to determine whether unencrypted signals are being spoofed.

Abstract: A practical method for adding new high-performance, tightly integrated Nav-Com capability to any Global Navigation Satellite System (GNSS) user equipment requires no hardware modifications to the existing user equipment. In one example, the iGPS concept is applied to a Defense Advanced GPS Receiver (DAGR) and combines Low Earth Orbiting (LEO) satellites, such as Iridium, with GPS or other GNSS systems to significantly improve the accuracy, integrity, and availability of Position, Navigation, and Timing (PNT) and to enable new communication enhancements made available by the synthesis of precisely coupled navigation and communication modes. To achieve time synchronization stability between the existing DAGR and a plug-in iGPS enhancement module, a special-purpose wideband reference signal is generated by the iGPS module and coupled to the DAGR via the existing antenna port.

Abstract: A practical method for adding significant new high-performance, tightly integrated Nav-Com capability to any Global Navigation Satellite System (GNSS) user equipment, such as GPS receivers, requires no hardware modifications to the existing user equipment. In one example, the iGPS concept is applied to a Defense Advanced GPS Receiver (DAGR) and combines Low Earth Orbiting (LEO) satellites, such as Iridium, with GPS or other GNSS systems to significantly improve the accuracy, integrity, and availability of Position, Navigation, and Timing (PNT)—in some cases by three orders of magnitude, to enable high precision GNSS carrier phase observable to be more readily exploited to improve PNT availability—even under interference conditions or occluded environments, and to enable new communication enhancements made available by the synthesis of precisely coupled navigation and communication modes.

Abstract: A navigation system provides a significant level of protection against all forms of interference or jamming to GPS in a cost-effective way. The system employs a network of ground reference stations and Low Earth Orbiting (LEO) satellites in conjunction with GPS. A common-view ranging geometry to a GPS satellite is established that links a reference station and a user. A second common-view geometry to a LEO satellite between the same reference station and user pair is also established. The ground stations synthesize real-time aiding signals by making carrier phase measurements of GPS the LEO satellite signals. This aiding information is transmitted via the LEO satellites to the user receiver at high power to penetrate ambient jamming. The user receiver locks onto the carrier phase of the LEO satellite, demodulates the aiding information, then applies the carrier phase measurements and the aiding information to enable extended coherent measurements of the GPS signals.

Abstract: A navigation system provides a significant level of protection against all forms of interference or jamming to GPS in a cost-effective way. The system employs a network of ground reference stations and Low Earth Orbiting (LEO) satellites in conjunction with GPS. A common-view ranging geometry to a GPS satellite is established that links a reference station and a user. A second common-view geometry to a LEO satellite between the same reference station and user pair is also established. The ground stations synthesize real-time aiding signals by making carrier phase measurements of GPS the LEO satellite signals. This aiding information is transmitted via the LEO satellites to the user receiver at high power to penetrate ambient jamming. The user receiver locks onto the carrier phase of the LEO satellite, demodulates the aiding information, then applies the carrier phase measurements and the aiding information to enable extended coherent measurements of the GPS signals.

Abstract: A real-time software receiver that executes on a general purpose processor. The software receiver includes data acquisition and correlator modules that perform, in place of hardware correlation, baseband mixing and PRN code correlation using bit-wise parallelism.

Abstract: A real-time software receiver that executes on a general purpose processor. The software receiver includes data acquisition and correlator modules that perform, in place of hardware correlation, baseband mixing and PRN code correlation using bit-wise parallelism.

Abstract: A real-time software receiver that executes on a general purpose processor. The software receiver includes data acquisition and correlator modules that perform, in place of hardware correlation, baseband mixing and PRN code correlation using bit-wise parallelism.