Abstract: A motion controlling system for providing a motion control signal to a motor driving a wheel of a medical equipment carriage is described. The system includes a handle having an end movably supported by the carriage so as to permit movement of the handle end relative to the carriage in a direction in which movement of the apparatus is desired, The system is also provided with an optical position encoding means, coupled between the handle end and the carriage, for providing a position signal indicating the position of the handle end relative to the carriage. A motion control means, responsive to the position signal from the optical position encoding means, provides a motion control signal to the motor. Several embodiments of the optical position encoding means, which include photodiode arrays and solar cells, are described.

Abstract: Methods and apparatus for measuring propagation delay over a line without interfering with data communications over the line are disclosed. A known signal is sent and looped back over a secondary channel, and the loop time is measured. Because the known signal is sent at a non-interfering frequency at the edge of the passband, the loop time minus fixed delay times of the communicating means does not provide a true measure of propagation delay. Rather, the envelope delay distortion must be determined and also subtracted from the loop time. The envelope delay distortion is determined as a function of the utilized non-interfering frequency and the line length, the latter of which may be estimated from the loop time.