Disclosed is a method of transferring data files from an internal memory within a portable wireless communication device to an external storage device by means of a wireless communication network. The clock data recovery circuit comprises a transmission line, a phase locked loop, a voltage controlled oscillator, a phase selector, and a D flip-flop. The indication of said prediction mode level is programmable and can be set at different levels. The offsets may extend upwardly andor downwardly from the major plane. A downset is formed at the center of the probe head carrier. This eliminates influence of a shake, and allows accurate aiming at a faraway target and measurement of a distance thereto with high accuracy.