Jamming Technology Introduction
The satellite navigation system represented by GPS is very vulnerable to intentional or unintentional interference signals as receiving very weak signals transmitted approximately 20,000km above from ground level. Recently in the U.S., major GPS-based navigation equipment at an airport went down due to a miniature sized cigar jack jammer, so called privacy protecting device. Also in Korea, intentional jamming attacks by North Korea prevented timing GPS receivers for mobile communication systems and DGPS reference station receivers from receiving the satellite signals.
The technology to significantly improve the anti-jamming capability of the satellite navigation receiver against external interference signals can be classified into 3 parts. The first is the CRPA(Controlled Reception Pattern Antenna) method able to deal with all types of interference signals controlling the reception pattern to minimize the incoming jamming signals using the size and phase information of jamming signals received from each array antenna different from the conventional antennas with fixed reception patterns. The second method can only deal with narrowband interference signals by detecting the frequency of interference signal incoming through the antenna with appropriate signal processing method and eliminating only the frequency band. The last method is to control the signal tracking loop bandwidth inside the receiver by getting help from different navigation sensors or verifying the navigation results.
Anti-jamming Technology Classification
SFAP: Space Frequency Adaptive Processing
STAP: Space Time Adaptive Processing
Anti-jamming Effect of Anti-jamming Technology for Satellite Navigation Receivers
Navcours Jamming Technology Introduction
Navcours possess the anti-jamming technology applicable to all systems through knowledge and experiences of the in-depth understanding on satellite navigation systems and developing/producing satellite navigation receivers in diverse weapons systems and application fields for extensive periods.
Navcours Major Technologies
For the Antenna-based AJ Technology using array antennas to eliminate interference signals, there is the analog method and the digital method depending on the signal processing method. Generally the digital method has a better ability to eliminate jamming signals compared to the analog method, but the analog method CRPA is generally used for satellite navigation receivers used for time synchronization due to additional time delays occurred during the signal processing. Navcours has the self-developed jamming signal eliminators based on the analog method and digital method array antennas.
Depending on the jamming signal detecting and eliminating method, the anti-jamming technology using the adaptive filtering has the method of eliminating the interference signal using the FFT/IFFT within the frequency domain and the method of using the Adaptive Transversal filter within the timing domain. Navcours has the products implementing both of these methods.
Navcours also has the technology to improve the anti-jamming capability by appropriately adjusting the bandwidth of the signal tracking loop combining with the inertial sensor or considering the dynamic characteristics of the satellite navigation receiver.