A demodulator comprises a first-stage carrier demodulator and a second-stage carrier demodulator. The first-stage carrier demodulator is configured to remove or compensate for the tracking error in the baseband signal, where the tracking error comprises aggregate, channel tracking error of carrier phase for the same received band, sub-band, (baseband) GNSS satellite channel, or set GNSS channels. The second stage carrier demodulator is configured to remove or strip a carrier signal component without any unwanted image or carrier-related frequency artifacts and to prepare for correlation-based decoding or demodulation of the encoded baseband signal by the correlators. First correlators are configured to determine correlations for code phase tracking loop, where the code phase tracking loop is configured to estimate a corresponding code error component of the tracking error for the code local oscillator for a respective channel. Secondary correlators are configured to determine correlations for a carrier phase tracking loop, where the carrier phase tracking loop configured to estimate a corresponding aggregate feedback error for multiple channels or a set of channels.

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.

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.

Disclosed is a method for global navigation satellite system (GNSS) positioning and an electronic device performing the method. According to an example embodiment, the method includes monitoring whether an error of the GNSS positioning occurs, determining, when the error of the GNSS positioning is detected, whether a first output frequency of a first phase locked loop (PLL) used for demodulating a GNSS signal received from a satellite for the GNSS positioning is stable, and changing, when the first output frequency of the first PLL is unstable, a frequency used for demodulating the GNSS signal to a second output frequency of a second PLL or a basic frequency input to the first PLL and the second PLL.

Disclosed is a method for global navigation satellite system (GNSS) positioning and an electronic device performing the method. According to an example embodiment, the method includes monitoring whether an error of the GNSS positioning occurs, determining, when the error of the GNSS positioning is detected, whether a first output frequency of a first phase locked loop (PLL) used for demodulating a GNSS signal received from a satellite for the GNSS positioning is stable, and changing, when the first output frequency of the first PLL is unstable, a frequency used for demodulating the GNSS signal to a second output frequency of a second PLL or a basic frequency input to the first PLL and the second PLL.

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.

A pay television satellite broadcast includes validation data that can be used to validate authenticity of live global positioning system (GPS) data. The validation data may be included within entitlement messages and encrypted for security and selective reception by authorized receivers. A navigation system may compute checksums of received live GPS data and compare with the validation data for a match. A decision about whether or not to use the live GPS data may be taken based on whether or not the computed checksums match the validation data received via the pay television satellite broadcast signals.

A system and method for detecting multiple spoofed or faulty global navigation satellite signals are provided. The system comprises a single antenna configured to receive satellite signals from a plurality of global navigation satellites, the single antenna located on a vehicle; a receiver in the vehicle, the receiver coupled to the single antenna; and at least one processor in the vehicle, the processor in communication with the single antenna through the receiver. The processor is operative to determine a unit vector in a direction from the vehicle to a global navigation satellite in local coordinates, from the satellite signals; determine a plurality of signal blocks, wherein the signal blocks are a collection of subsets of the satellite signals and a covariance matrix for the satellite signals; and determine which satellite signals in the signal blocks are spoofed or faulty by comparing a geometry of the local coordinates with satellite coordinates.