Light duration measuring method, involves mixing multiple clock signals of two clock controls in mixer for forming mixed signal, and utilizing phase shift between mixed signal and filter signal for determining light duration

摘要

The method involves radiating a light signal in an angle to another light signal in a photodiode (13) and mixing the two light signals to a common received signal (S13). The common received signal is filtered with a filter (25) for forming a filter signal, and the frequency response of the common received signal corresponds to a frequency of a clock difference. Multiple clock signals of two clock controls (16, 17) are mixed in a mixer (30) for forming a mixed signal. A phase shift between the mixed signal and the filter signal is utilized for determining the light duration.