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Optical Engineering

Range ambiguity resolution technique applying pulse-position modulation in time-of-flight scanning lidar applications
Author(s): Peter Rieger
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Paper Abstract

Time-of-flight (ToF) range measurements rely on the unambiguous association of each received echo signal to its causative emitted pulse signal. This definite association is difficult when measuring long ranges at a high repetition rate, resulting in ambiguous range measurements. While methods and algorithms exist to overcome this fundamental problem of ToF measurement techniques like radar these may not be directly applied to lidar without adaptations. Especially, in airborne laser scanning, up to now it was a requirement to strictly avoid range ambiguities during data acquisition. We present a new method for resolving range ambiguities fully automatically in scanning lidar, enabling measurements exceeding the maximum unambiguous measurement range by far. As a theoretical foundation of our approach, we introduce a specific model of the lidar transmission path (i.e., emitter–target–receiver) accounting for the time-variability of consecutive measurements. Based on this model, we discuss the influence of intentional variation of the intervals between pulse emissions on the intervals of successively received echoes and delineate an algorithm for automated, definitive association of pulse emissions and their resulting echoes. Simulation results indicate a probability of incorrect associations of <10 5 , which we positively proved by applying this technique to real-world scan data.

Paper Details

Date Published: 13 February 2014
PDF: 13 pages
Opt. Eng. 53(6) 061614 doi: 10.1117/1.OE.53.6.061614
Published in: Optical Engineering Volume 53, Issue 6
Show Author Affiliations
Peter Rieger, RIEGL Laser Measurement Systems GmbH (Austria)

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