Abstract: A set of sensors or sensor pairs capable of detecting the presence of a person passing through a portal is used for monitoring the portal. In one embodiment the portal has spaced apart upright supports. On one of the upright supports is mounted the sensors and the other upright support is used as a surface for reflection of the wave energy transmitted. When a person is present in the portal the person reflects the wave energy. The receiver is capable of detecting the time duration between transmission and receipt of the wave energy signal. In a second embodiment, the sensors are mutually inductively coupled in pairs. When a person is present within the portal the mutual inductance is changed in one or more of the sensor pairs. This change in mutual inductance is sensed and used as a means for determining which person is present in the portal. For example, a family may comprise two adults, a teenager, a preteen and a small child.

Abstract: A videofluoroscopy system for use in vivo, real-time, motion analysis includes a fluoroscopy system for producing a series of x-ray images of a subject, a video recorder for recording the x-ray images as video frame images, a video playback unit for providing a playback output of individual video image frames one at a time, a frame grabber connected to a display monitor for converting each image frame into graphics data and displaying a selected viewing area thereof on the monitor, a marking device for marking selected points within the viewing area of each image frame, and a computer processor for controlling the frame grabber, display, and marking device in order to define the viewing area, detect X-Y coordinates for the selected points, and store the coordinates of the marking points as motion data. The frame grabber is implemented as a module connected to the computer processor which automatically operates the video playback unit and converts the image frames one frame at a time to digital graphics data.