GNSS anti-jamming devices perform an important role in mitigating the intentional and unintentional interference of Global Navigation Satellite Systems signals, providing mission-critical defense systems with continuous, assured access to GNSS position, navigation and timing information.
Anti-Jam Technology for Defense
GNSS satellite signals, such as GPS, are crucial for a wide range of military systems, providing position, navigation and timing (PNT) for infantry, armored vehicles, naval vessels, UAVs (unmanned aerial vehicles) and more.
By the time they reach the GNSS receivers in equipment and vehicles, the power level of these signals is relatively weak, making them susceptible to interference sources that can cause jamming or spoofing.
GNSS jamming is caused by interference on the GNSS signal frequencies that overpowers the satellite signals, and may be done deliberately or occur unintentionally as a result of faulty electronic equipment or electromagnetic radiation from space. Spoofing uses fake GNSS signals to overcome the legitimate satellite transmissions and make the receiver think it is somewhere other than its true location.
GNSS Anti-Jamming Technology
Anti-jamming technology includes the use of special GNSS receivers that use filtering and signal processing to reject unwanted signals, which is especially effective for out-of-band interference. GNSS anti-jamming receivers may also be able to detect jamming signals by measuring signal strength – these signals may be higher-powered than the weak legitimate GNSS signals.
Anti-jam antennas can also be installed that can figure out the direction of the jamming signal and introduce “nulls” that decrease the effectiveness of the jammers.
An adaptive antenna array made up of CRPAs (controlled reception pattern antennas) can be used to mitigate a wide range of interference, even at frequencies that are very close to legitimate GNSS signals.
GNSS anti-spoofing measures include the use of authentication technology such as Galileo’s OSNMA (Open Service Navigation Message Authentication), which uses secure cryptography to check and ensure the authenticity of navigation data. Military GPS users also have access to Y-code, which is broadcast on the L1 and L2 frequencies and uses a constantly changing encrypted binary code to fool spoofing attempts.