Method for processing an echo profile and a pulse-echo ranging system
View Patent ↗Pulse-echo ranging system are used in level measurement applications for determining the distance to a target object by measuring how long after transmission of a pulse an echo pulse is received. An echo profile ( 17 ) is generated and then processed to determine the temporal position of the echo pulse on a temporal axis. Based on the fact that the peak portion and the trailing edge of the echo profile are susceptible to be affected by the measurement environment and the target object itself, the accuracy in determining the echo arrival time is increased, by the steps of fitting a branch of a parabola ( 19 ) to a selected portion of the leading edge ( 18 ) of the echo profile ( 17 ) and determining the temporal position of the fitted parabola ( 19 ) on the temporal axis.
1. A method for processing an echo profile generated by a pulse-echo ranging system to determine the temporal position of an echo pulse on a temporal axis, comprising:
fitting a branch of a parabola to a selected portion of the leading edge of the echo profile;
determining the temporal position of the fitted parabola on the temporal axis, wherein the width of the parabola is varied to fit the parabola to the selected portion of the leading edge, and wherein the determination of the temporal position of the fitted parabola on the temporal axis is applied for far ranges and for near ranges a determination of a temporal position of the echo pulse from the center of mass of the echo profile is used.
2. The method according to claim 1 , wherein a temporal position of a peak of the echo pulse is evaluated to determine whether the echo pulse is in the far range or in the near range.
3. A pulse-echo ranging system for measuring a distance to a target object, comprising:
a transmitter for controlling a transducer to emit at least one pulse of high frequency energy towards the target object;
a receiver for receiving an echo pulse from a direction of the target object to the transducer to provide a echo profile; and
a controller for determining the distance to the target object by evaluating the echo profile,
wherein a branch of a parabola is fitted to a selected portion of a leading edge of the echo profile and a temporal position of the parabola on the temporal axis is determined,
wherein a controller is programmed to fit the branch of the parabola, the controller is further programmed to vary the width of the parabola to fit the parabola to a selected portion of the leading edge, and
wherein the parabola is used for far ranges and the controller is further programmed to determine the temporal position of the echo pulse from the center of mass of the echo profile for near ranges.
4. The pulse-echo ranging system as claimed in claim 3 , wherein the controller is further programmed to evaluate the temporal position of the peak of the echo pulse to decide whether the echo pulse is in the far range or in the near range.