A Multiple-Antenna Software GPS Signal Simulator for Rapid Testing of Interference Mitigation Techniques

Russell Powell, Joshua Starling, and David Bevly

Abstract:	This paper details the design of a software GPS signal simulator and illustrates how it can be used to support rapid testing of GPS interference mitigation research. The MATLAB-based signal simulator is capable of generating digital GPS signals at intermediate frequencies (IF) for multiple-element, controlled-radiation-pattern-antenna (CRPA) configurations in jamming environments. The simulator was developed to support novel GPS interference mitigation research and analysis conducted in the GPS and Vehicle Dynamics Laboratory (GAVLAB) at Auburn University. The digital signals can be analyzed with software acquisition, tracking, and positioning techniques or can be converted to analog signals at the GPS radio frequencies and played to multiple receivers via cabling using the Universal Software Radio Peripheral (USRP) software-defined-radio (SDR) platform. A GPS IF-signal for a single antenna generated by the software simulator was played-back and recorded simultaneously with USRPs and compared to an IF-signal for the same scenario generated by a hardware GPS signal simulator which was also recorded with a USRP. Position and velocity measurements calculated by a software receiver from the simulated IF signal, the played-back and recorded IF signal, and the signal generated by the hardware simulator are compared to evaluate the baseline performance of the software simulator. Results of this experiment illustrate that a software simulator paired with the USRP is comparable in performance to the hardware simulator for single antenna applications. A four-element CRPA interference simulation was generated by the software simulator and analyzed with a software receiver that was modified to include multi-antenna interference mitigation techniques. Results provided from the CRPA simulation by the modified software receiver illustrate that a software GPS simulator is a powerful tool for rapid development of GPS interference mitigation techniques in the software domain. Lastly, the simulated CRPA signals were played-back and recorded simultaneously with multiple USRPs to examine the feasibility of using relatively inexpensive SDRs to simulate multiple-antenna GPS scenarios. Results from this test illustrate that a multiple-USRP setup is a useful tool for testing robust interference mitigation techniques.
Published in:	Proceedings of the 2017 International Technical Meeting of The Institute of Navigation January 30 - 2, 2017 Hyatt Regency Monterey Monterey, California
Pages:	714 - 729
Cite this article:	Powell, Russell, Starling, Joshua, Bevly, David, "A Multiple-Antenna Software GPS Signal Simulator for Rapid Testing of Interference Mitigation Techniques," Proceedings of the 2017 International Technical Meeting of The Institute of Navigation, Monterey, California, January 2017, pp. 714-729. https://doi.org/10.33012/2017.14922
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