Toyon Research Corporation proposes to develop a low-cost navigation system for unmanned aerial vehicles (UAVs) that achieves an attitude accuracy of better than 0.1 degrees using commercial-grade gyroscopes and accelerometers. An order of magnitude improvement in navigation performance will be achieved by fusing low-cost inertial sensor measurements with attitude and position measurements from a small-aperture GPS-based attitude (GPS/A) sensor. The Miniature Integrated Direction-finding Attitude-determining Anti-jam System (MIDAAS(TM)) obtains position, velocity, attitude, and time (PVAT) measurements directly from GPS signals. MIDAAS employs an innovative small single-aperture antenna to compute full 3-D attitude (roll, pitch and yaw) using only two RF channels, leading to a smaller, simpler, lower-cost GPS/A receiver system. A stand-alone (gyro-less) MIDAAS unit can also be used to provide attitude information in addition to position and velocity on very small platforms. A unique ultra-tightly coupled (UTC) navigation architecture makes the system inherently more robust to interference and significantly improves the attitude estimate. In addition, MIDAAS provides active anti-jam protection and multipath mitigation thereby further improving the system integrity and robustness. The system performance will be demonstrated during the Phase I effort with data obtained during several flight tests, and will be compared with a higher-accuracy, more expensive GPS/IMU system.