This project is developing a very novel noncontact microwave sensor system that detects the presence and activity of participants in front of interactive surfaces or structures. We are taking two approaches. In one, we have embedded a real-time software feature detector onto a small, micropatch Doppler motion-detection radar�this device produces a continuous data stream that specifies the amount of motion detected, the dominant speed, and the dominant direction to and from the radar antenna. We are also adapting a low-power ranging radar originally designed by one of our sponsor collaborators to detect the level of fluid in large fuel tanks into a much smaller package able to determine the distance to users as they approach interactive surfaces or devices. Unlike IR, vision, or sonar systems, these techniques aren't affected by lighting, clothing, or visual clutter. Unlike capacitive sensing, we can design antennae to direct the sensing region into a forward-looking beam.These devices can also sense through opaque, nonconductive material, such as plastic, wood, or wallboard.