Q: What special considerations should be taken into account for testing and simulating against GNSS jamming and spoofing?
A: Current integrations of GPS include a controlled reception pattern antenna (CRPA). Testing with a standard interference or jamming source will not provide accurate results. Wavefront generator simulators are capable of outputting signals that correctly stimulate the GPS receiver’s antenna electronics. All of the signals are correctly displaced according to the antenna’s reception pattern with a jamming source that is coherent.
A: Testing GNSS receiver spoofing and jamming resilience under real-life scenarios requires mixing live-sky GNSS signals with synthesized spoofed signals. This requires the spoofing signal generator to be time- and position-locked to the live-sky signal to within nanoseconds. GNSS simulators that allow nanosecond-level synchronization to live-sky signals can enable such testing. Low-cost simulators can enable testing with multiple simultaneous spoofers/jammers.
A: With the sophistication of GNSS threats, simulators should be able to generate a variety of interferences and jammers that users can easily control. Also, the jammers’ characteristics (Doppler, power level, and so on) should reflect the dynamic of the vehicle and jammers. Such characteristics are almost impossible to simulate when the jamming source is not integrated with the simulator.
A: For jamming, test for multi-frequency/constellation, accurately controlling jamming-to-signal ratios and strength levels, and simulate several types of jammers: carrier-wave, sweep, noise, FM chirp and so on. For spoofing, two synchronized simulators are best: one for the live sky and one for the spoofer. Tightly control the sync accuracy, the relative power between the two signals, and the spoofer’s estimation accuracy of the target’s position.
A: Antenna technology, directionality and filtering have a large part to play in mitigating the impact of jamming and spoofing. Conventional laboratory receiver testing often overlooks the effect of the antenna. New approaches need to be developed to allow antenna effects be incorporated into testing either by including the antenna to be part of the test setup or by accurately simulating the directionality/filtering capability of the antenna.
A: Most jamming occurs due to RFI used to keep positioning unavailable. As such, typical jammers are CW or sweep-CW. Testing is then mostly a matter of proper jamming-to-signal simulation. On the contrary, spoofing aims at luring the receiver from its true position. Simulations are difficult as slowly power increasing spoofing signals must be synchronized with true received signals to take over the locked tracking loops.