Research and design of synchronous GPS spoofing signal generation technology

In order to meet the actual requirements of navigation spoofing of "low, slow, small" UAV, a miniaturized synchronous GPS spoofer has been developed based on our asynchronous GPS generator spoofer. Firstly, based on asynchronous GPS generator spoofer RF signal model, considering the spoofer signal processing delay, the spoofing signal propagation delay, the status of the authentic satellite signal received by the UAV receiver, and the dynamic model of the UAV, established the mathematical model to accurately calculate the simulation time and state parameters of the synchronous spoofing signal. Secondly, a local timing receiver is employed to provide the disciplined reference clock and 1 pulse per second (1PPS) signal to synchronize the spoofing signal with the authentic system time, and high-order direct digital synthesis(DDS) technology is applied to accurately control the signal parameters and ensure that the difference between the spoofing signal and the authentic signal is within the tolerances allowed for successful spoofing when the spoofing signal reaches the phase center of the receiving antenna of the target receiver. Finally, the test results using a popular commercial UAV and a commercial receiver are presented. When the UAV receiver tracks the authentic satellite signal, the synchronous GPS spoofer begins to transmit the spoofing signal, which gradually deviates the target receiver from its normal measurements and makes it output the position and velocity results under control. The results verify the established synchronous signal model, the designed synchronous signal generation circuit, and indicate the synchronous GPS spoofer can achieve navigation spoofing of commercial UAV and commercial receiver.