Trimble Navigation Limited

Robert J Lamm

Geoffrey R Kirk

A system and method for selecting at least one target with strong reflectivity from a set of strong and weak reflectors by using an amplitude of a reflected signal to make such a selection. The pre-computed look-up table that relates an amplitude of the reflected signal from a target with a strong reflectivity to the distance at which such target is located is used in a real-time mode to separate weak reflectors from strong reflectors. In the post-processing mode the usage of normalizing function allows to further differentiate between strong reflectors (like windows) and very strong reflectors (like prisms).

Differentiation of targets in optical station based on the strength of the reflected signal

A distance interpolator incorporated into a total station and a method for digitally interpolating a distance measurement from the total station to a target, such that the distance interpolator measures the distance from the total station to the target using primarily digital electronics and statistical analysis. In one embodiment, the total station transmits an energy pulse from the electronic distance measuring portion of the total station, with the energy pulse directed at the target. This embodiment then receives at the electronic distance measuring portion the energy pulse reflected from the target. This embodiment also contains a reference oscillator and digital counter, which counts the number of reference oscillator clock pulses that elapse from the time the energy pulse is transmitted to the time the reflection of the energy pulse is received. This embodiment further accumulates counts for a number of additional energy pulses, and then calculates the average value of the counts over all energy pulses transmitted. This embodiment then calculates the distance between the total station and the target using the average value of the counts, the frequency of the reference oscillator, and the speed of light in the environment in which the counts were obtained.

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Mountain View, CA, United States of America

Robert J Lamm