Engineering topics
Publications and source records attributed to Guy, W. J..
An automatic focusing system designed around an ultrasonic range measurement is described. Besides maintaining the focus, subject distance is a by-product which could lighten the NOVA computational effort. An automatic head tracking unit is also discussed. It is intended to reduce the search time required when track is lost. An X-Y ultrasonic measurement is also made in this design to control the deflection mirrors.
Ultrasonic tracking techniques are investigated for an oculometer. Two methods are reported in detail. The first is based on measurements of time from the start of a transmit burst to a received echo. Knowing the sound velocity, distance can be calculated. In the second method, a continuous signal is transmitted. Target movement causes phase shifting of the echo. By accumulating these phase shifts, tracking from a set point can be achieved. Both systems have problems with contoured targets, but work well on flat plates and the back of a human head. Also briefly reported is an evaluation of an ultrasonic ranging system. Interface circuits make this system compatible with the echo time design. While the system is consistently accurate, it has a beam too narrow for oculometer use. Finally, comments are provided on a tracking system using the Doppler frequency shift to give range data.