GPS Signal Simulation using Open Source GPS Receiver Platform

Embedded GPS receivers have become commonplace with the proliferation of GPS navigation systems into all but the least expensive vehicle and cell phone lines. As more manufacturers embed low-cost GPS receivers into their products, the need for low-cost GPS signal simulators has also grown. Controlled virtual testing is vital in ensuring the expected system performance. NAVSYS developed a low cost, SDR-based GPS signal generator to address a broad range of research, academic, industrial, and defense applications. The system is designed to be flexible, scalable, and most importantly, inexpensive. The NAVSYS GPS signal simulator leverages the capabilities of the Ettus Universal Software Radio Peripheral (USRP) radio and the NAVSYS GPS Signal Simulation Toolbox to provide users with a GPS signal generation capability at a much lower cost than currently available on the market. The combination of the NAVSYS GPS signal simulation software coupled with the record and playback capability of the USRP makes for an extremely low cost, yet highly flexible, GPS signal simulation capability. INTRODUCTION As more manufacturers embed low-cost GPS receivers in to their products, the need for low-cost GPS signal simulators has also grown. Controlled virtual testing is vital in ensuring the expected system performance. Many GPS signal generators are available that are designed specifically for high volume production test applications for devices that use commercial GPS/SBAS, GLONASS, and Galileo receivers. Often the cost of these high-end simulators is beyond the reach of small companies or universities. In response to this need, NAVSYS developed the NAVSYS SDR Control Unit (SCU) and GPS Signal Architect scenario software to address a broad range of research, academic, industrial, and defense applications. Figure 1 shows the NAVSYS GPS signal simulator hardware. It is designed for use with commercial software designed radios such as the Ettus N210 USRP radio and is based on NAVSYS GPS Signal Simulation Toolbox.