The present invention sequentially and repeatedly accepts a plurality of types of information that can change with time, including position information obtained using a satellite signal, and correlates and records the accepted plurality of types of information with time information.

Systems and methods for calculating single delta range differences using synthetic clock steering are provided. In certain embodiments, a system includes a first GNSS receiver that provides first delta range measurements and first measurement times associated with a plurality of GNSS satellites. The system further includes a second GNSS receiver that provides second delta range measurements and second measurement times associated with the plurality of GNSS satellites. Additionally, the system includes a processing unit that executes instructions that cause the processing unit to synchronize the second delta range measurements with the first delta range measurements to create synchronized delta range measurements. The executable instructions also cause the processing unit to calculate a single difference of the first delta range measurements and the synchronized delta range measurements for at least one satellite in the plurality of GNSS satellites.

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.

Authentication mechanism is provided to open service signals in Global Navigation Satellite Systems (GNSS), by inverting a plurality of bits in a pseudorandom noise code in a GNSS signal having a predetermined period of a binary bit sequence of N bits. A position of each inverted bit in the binary bit sequence is specified by a serial number generated for each period using a cryptographic pseudorandom number generator, where at least one of the position of the inverted bit and a number of the inverted bits in the period varies period by period. A decryption key is provided to a GNSS receiver, which correlates, using a corresponding cryptographic pseudorandom number generator, the received GNSS signal, and accumulates an amplitude thereof at the inverted bit, thereby determining if the received signal is counterfeit based on the ratio of the inverted bit amplitude with respect to the signal amplitude.

A method for detecting a presence of interference during global navigation satellite system (GNSS)-based and inertial sensor signals (INS)-based localization of a vehicle includes determining localization results using a first filter configured to read in GNSS data and INS data, and storing a plurality of the determined localization results. The plurality of the determined localization results are after one another in terms of time and are each determined using the first filter. The method further includes analyzing the stored plurality of localization results using a second filter which differs from the first filter.

A system wherein when a normal state is entered: discipline only one of at least three oscillators to an external reference; output frequency and time based on the other oscillators not being disciplined to the external reference; and monitor the output frequency difference of the one of the oscillators being disciplined and a composite value of the output frequency difference among the other oscillators. A spoofing state is identified when the monitored difference is more than a difference threshold. When the spoofing state is identified: reset the frequency and time of the oscillator in the spoofing state to match the composite value of the other oscillators; resume disciplining the oscillator in the spoofing state from the external reference after expiration of a time period; and clear the spoofing state and return to the normal state when the oscillators have the output frequency differences among the oscillators below the difference threshold.

A system for identifying spoofed navigation signals includes a multi-element antenna configured to receive a plurality of navigation signals. The system also includes at least one processor configured to determine an angle of arrival for each of the navigation signals and analyze the angles of arrival for the navigation signals to determine whether one or more of the navigation signals are spoofed. To analyze the angles of arrival for the navigation signals, the at least one processor may be configured to (i) determine whether two or more of the navigation signals were received at substantially the same angle of arrival (which may be based on a difference of less than 5° between the angles of arrival) and/or (ii) compare the angles of arrival for the navigation signals to at least one expected angle of arrival (which may be based on information about expected or actual positions of multiple satellites).

In some examples, a system includes a transceiver configured to receive surveillance messages from Y target vehicles, where Y is an integer greater than two. The system includes processing circuitry configured to determine predicted positions of the Y target vehicles based on the surveillance messages. The processing circuitry is also configured to determine reported positions of the Y target vehicles based on later received surveillance messages. The processing circuitry is further configured to determine that respective differences between the respective predicted position and the respective reported position for X of the Y target vehicles is greater than a threshold distance. The processing circuitry is configured to determine that Global Navigation Satellite System interference has occurred in response to determining that X divided by Y is greater than a threshold level.

A multibeam Radio Frequency (RF) lens antenna is designed as a receiver for Global Navigation Satellite System (GNSS) applications, such as GPS (Global Positioning System), Galileo, GLONASS, COMPASS, and others. The RF lens and plurality of associated feed elements and receiver circuits combine to form a plurality of resulting high-gain relatively narrow beams that, taken together, allow reception of signals from GNSS satellites over the entire upper hemisphere. Any kind of RF lens can be used, where the lens can be of homogeneous or inhomogeneous, dielectric or metamaterial/metasurface construction. The benefit of this approach to build a GNSS receiver over existing alternatives is increased gain and decreased noise at each receiver, which improves the signal to noise ratio (SNR) and improves the accuracy and reliability of the position and time measurements, while also reducing the impact of, and sensitivity to, interference, jamming, and spoofing signals. The approaches described in this patent can be combined with existing signal processing and accuracy improvement methods (such as Real-Time Kinematic (RTK), Precise-Point Positioning (PPP), and Differential GPS (DEPS)) for further benefits. This system has applications within the surveying, maritime, land mobility, aerospace, and government positioning market areas.

Several examples of a navigation disruption device and methods of using the same are described herein that use real-time, low-cost computation to generate conflicting/competing signals to actual Global Navigation Satellite System (GNSS) signals. For example, the novel, hand-held navigation disruption devices described herein (1) generate signals from a simulated satellite constellation, wherein the signals from the simulated satellite constellation conflict/compete with signals from one or more actual satellite constellations, and (2) transmit the signals from the simulated satellite constellation(s) towards an unmanned vehicle. The signals from the simulated satellite constellation(s) cause the unmanned vehicle to compute an incorrect position, which in turn disrupts its ability to navigate and operate effectively.