In a system, a detecting module cyclically detects positional information of reflection points of received echoes. A sampling module cyclically samples, from the detected reflection points for each cycle, first and second reflection points. The first and second reflection points are expected to be reflection points of the respective first and second reflective portions of a moving object in front of the system. A first determining module determines whether a distance between the first and second reflection points varies over time. A second determining module determines that the first and second reflection points correspond to reflection points of the respective first and second reflective portions of a single moving object when it is determined that the distance between the first reflection point and the second reflection point is substantially invariant over time.