The Ashtech G12-HDMA: A Low Cost, High Performance GPS Space Receiver

The Ashtech® G12-HDMA™ is a 12-channel GPS receiver developed for High Dynamics and Missile Applications. It has successfully flown on several Navy sea-launched test missiles, as well as on sounding rockets launched by NASA at its Wallops Island facility. The G12-HDMA is currently being integrated into the X-34 experimental reusable launch vehicle being developed by Orbital Sciences. Recent firmware modifications have also enabled the G12-HDMA to be used by low Earth orbiting spacecraft for navigation, timing, and precise orbit determination. In this paper, the performance of the G12-HDMA in a variety of missile, rocket, and spacecraft navigation tests are described. The missile and rocket tests utilized real GPS signals in real-time and post-processed navigation applications. The spacecraft tests utilized simulated GPS signals from a state-of-the-art GPS signal simulator. The test results include acquisition, tracking, and navigation performance.