UAVs (unmanned aerial vehicles) and drones can be jammed by interference that affects the GNSS satellite signals needed for position, navigation and timing (PNT). This interference can cause drones that utilize RTK and PPP to switch to less precise positioning methods, or in the worst case lose tracking and positioning capabilities altogether.
TUALAJ GPS/GNSS CRPA Anti-Jamming System by TUALCOM
GNSS signals can also be spoofed. Spoofing involves using fake GPS signals that overcome weaker legitimate signals and are picked up by the drone’s receiver antenna. These fake signals cause the drone to assume it is at a completely different location, and this can result in a crash or can be used to force the drone to attack or spy on different targets to those originally intended.
Drone anti-jamming receivers use filtering and signal processing to reject interference, and may look for anomalies such as signals that are stronger than the usually relatively weak GNSS signals. Some receivers can handle even the most complex of jamming interference, such as frequency-hopping signals.
Anti-Spoofing & Anti-Jamming GNSS Receiver by Meteksan Defense
Anti-jamming antennas can be used that do not require replacement of the original GNSS receiver. They can locate the direction of the jamming signal and introduce “nulls” that decrease the effectiveness of the jammers. Controlled Radiation Pattern Antennas (CRPAs) may be used to provide a dynamically controlled pattern that optimises the GNSS signal-to-noise ratio, making it easier to reject interfering signals.
GAJT®-710ML Anti-Jamming GPS Antenna by Novatel
Anti-spoofing systems may use signals designed to prevent spoofing, such as Galileo OS-NMA and E6, or the GPS military code. They may also use advanced signal processing algorithms to detect spoofed signals by looking for anomalies. Dual polarized antennas can also be used to detect and mitigate a spoofing attack by measuring the radiation patterns of spoofed signals and comparing them to authentic satellite signals.
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