A system for detecting satellite signal spoofing using error state estimates is provided. The system includes at least one satellite receiver to receive satellite signals, at least one memory and at least one controller. The at least one memory is configured to store at least operation instructions. The at least one controller is in communication with the at least one satellite receiver and the at least one memory. The at least one controller is configured to determine state estimates from the received satellite signals. The at least one controller is further configured to determine error state estimates based at least in part on differences in current state estimates and differences in delayed state estimates. The controller further configured to determine if spoofing is occurring in one more of the received satellite signals when the error state estimates are greater than a select threshold.

Systems and methods for GNSS spoofing detection using C/No based monitoring are provided. In certain embodiments, a system including at least one GNSS receiver that provides C/No for GNSS signals received from GNSS satellites. The system also includes a processor coupled to the at least one GNSS receiver. The processor executes instructions that cause the processor to calculate new C/No comparison values based on the C/No measurements and previous C/No comparison values. Further, the instructions cause the processor to compare the C/No measurements against the previous C/No comparison values. Moreover, the instructions cause the processor to determine whether one or more of the GNSS signals are spoofed based on the comparison of the C/No measurements against the previous C/No comparison values. Additionally, the instructions cause the processor to set the new C/No comparison values as the previous C/No comparison values.

The positioning signals broadcast by the GNSS constellations on civilian frequencies are likely to be counterfeited, while the use of authentic signals is becoming increasingly critical for certain applications. According to the invention, the authentication of GNSS signals is performed by analysis of consistency between the measurements of parameters characteristic of the signals (direction of arrival, amplitude, phase) and their state model, said state model taking account of an emulation by software and electronic means of displacements of the phase centre of the antenna and/or of the main lobe of the radiation pattern. Advantageously, these displacements are generated by a pseudo-random code. Advantageously, the analysis of consistency between measurements and models is a multiple-criterion analysis, the combination of criteria being chosen as a function of a reception quality indicator and/or of a presumed location.

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.

Methods and systems detect physical locations of vessels. A first satellite includes a first image sensor. A second satellite includes a second image sensor. The processor receives a first image of a target area from the first image sensor, and a second image of the target area from the second image sensor. Both images are taken within a predetermined time frame. The processor performs image recognition to identify a vessel that appears in both the first image and the second image. The processor receives the first satellite's location and orientation when the first image is taken and the second satellite's location and orientation when the second image is taken. Each satellite's location and orientation are determined by the satellite's geographic determination module. The processor determines the vessel's location by performing triangulation based on the first satellite's location and orientation and the second satellite's location and orientation. The processor outputs data representative of the vessel's determined location. The vessel's speed and bearing are also determined by the processor.

A method for sensor operation includes deploying a network of sensors, which have respective clocks that are not mutually synchronized. At least a group of the sensors receive respective signals emitted from each of a plurality of sources, and record respective times of arrival of the signals at the sensors according to the respective clocks. Location information is provided, including respective sensor locations of the sensors. The respective clocks are synchronized based on the recorded times of arrival and on the location information. In the process the sources may be localized, or if the sources are far away, then their directions may be resolved. Sensor positions may also be resolved in the process.

An atomic clock is used in conjunction with the GNSS receiver and the inertial sensors, creating a more capable inertial navigation system (INS). The system can be composed of a GNSS receiver, an accurate clock, and a mechanism for measuring relative pose changes. For example, the system can utilize an inertial measurement unit (IMU) to provide the relative pose changes, but other mechanisms, such as visual or LADAR odometry, can be used. The GNSS receiver measures the pseudo-ranges to the GNSS satellites in the field of view. These measurements are “time tagged” with the accuracy of the atomic clock. The relative motion between the pseudo-ranges is measured using the IMU. Finally, a lock is achieved by filtering these measurements. The filtering mechanism can be a traditional Kalman Filter or other mechanisms that attempt to minimize a mean square error.

A vehicle unit adapted to receive a GNSS raw data signal, characterised in that it comprises a secure processor or secure microcontroller unit (MCU) adapted to authenticate the GNSS raw data signal and securely calculate a position of the vehicle unit based on the authenticated or to be authenticated GNSS raw data signal.

A circular grazing system for poultry and/or livestock. The circular grazing system including a center pivot structure installed at a field. The center pivot structure may have a center pivot axis. The field may be a poultry and/or livestock grazing field. The circular grazing system for poultry and/or livestock may include an enclosure for containing poultry and/or livestock. The enclosure may extend generally radially from the center pivot structure to a circumference of the field. The enclosure may be rotably coupled to the center pivot structure such that the enclosure rotates around the center pivot axis.

The present invention relates to a system and method using hybrid spectral compression and cross correlation signal processing of signals of opportunity, which may include Global Navigation Satellite System (GNSS) as well as other wideband energy emissions in GNSS obstructed environments. Combining spectral compression with spread spectrum cross correlation provides unique advantages for positioning and navigation applications including carrier phase observable ambiguity resolution and direct, long-code spread spectrum signal acquisition. Alternatively, the present invention also provides unique advantages for establishing the validity of navigation signals in order to counter the possibilities of electronic attack using spoofing and/or denial methods.