Abstract: Pulse transit time-based method for distance measurement employs a complex multi-parametric modulation of emitted pulses with adaptive control of the parameters of modulation. An evaluation of the pulse transit time-variable's observability in a measuring cycle is used as an input of the adaptive control loop. The achieved special pattern of received pulses provides for obtaining a vector of characteristic elements on the pattern with low sensibility to active and passive disturbances present during measurement. These characteristic elements are used by the method for the accurate measurement of the pulse transit time, and consequently, for the calculation of the distance between the emitter of pulses and the target.

Abstract: An acoustic method for measuring of a distance between an emitter of acoustic energy and a target object provides for an accurate measurement by having the measurement's outcome invariant to the speed of sound variations along the acoustical path between the emitter and the target. A plurality of emitters and a plurality of receivers are used in the invention. One acoustic emitter and one receiver are located in a spatial region such that the sent and the reflected acoustical energy passes along substantially same vertical line between the emitter and the target. Another acoustic emitter sends the acoustical energy at an angled direction to the same area on the target's reflecting surface as the first emitter does. The corresponding echo travels to another receiver. During the measurement, two specific variables are being monitored. The first variable is associated with the distance between the first emitter and the target.