Acquiring data in terrestrial laser scanning with high measurement rates over long ranges frequently results in range ambiguities. Instruments with multiple-time-around capability (MTA), like the RIEGL VZ-4000, include information in the acquired data which the RiMTA TLS utilizes to resolve these ambiguities. Instead of requiring users to manually specify the correct MTA zone for each data set or even subset of data, RiMTA TLS automatically calculates the MTA zone for each measurement .
In order to correctly determine the range to the target with a LIDAR instrument using time-of-flight measurements with short laser pulse intervals, it is necessary to correctly determine the correlation of each received echo pulse to its causative emitted laser pulse. However, at high pulse repetition rates (PRR) and large target ranges this definite allocation becomes ambiguous due to a limiting factor which may not be tweaked by engineer‘s skills: the speed of light. At a PRR of 300 kHz the range of unambiguity is limited to 500 meters, a measurement distance which is routinely exceeded by RIEGL terrestrial laser scanners (TLS).