In an embodiment, a computer-implemented method includes: causing a camera module to capture a plurality of frame portions with an exposure time at a sampling clock period. The frame portions correspondingly reflect a predetermined number of first signal pulses periodically generated by a light source. The exposure time corresponds to a duration of one of the predetermined number of first signal pulses. A first data sequence is encoded into the first signal pulses. The sampling clock period is different from a duration of the first data sequence such that a second data sequence is obtained from cycling through all of the first data sequence.