고-분해능 거리측정 LRF 시스템

Abstract

This thesis describes the development of a reconfigurable ring oscillator based time-to-digital converter (TDC), for a pulsed time-of-flight (TOF) laser rangefinder (LRF) system that is capable of making high resolution distance measurements. The biggest design challenges in the design of any TDC are related to the fact that the arrival moment of the hit signal is unknown and asynchronous with respect to the reference clock edges. Yet, the time interval measurement unit (TDC) must provide an immediate and unambiguous measurement result over the full dynamic range. This work presents a novel ring oscillator based time-of-flight LRF system architecture in which time is digitized to the nearest possible frequency multiples of some reference frequency, with minimum possible error. The reference frequency and its multiples are generated by ring oscillator. High resolution distance measurement is achieved by iteratively applying consecutive frequency components where the application of each frequency component provides a range of the distance to be measured, limited by the oscillator clock period. However this range is reduced to the nearest possible edges of the counter clocks from both sides of the hit signal to achieve maximum possible resolution.