A system to generate a navigation field relative to an implanted device is disclosed. For example, a wireless communication network may comprise a first system and a second system. Each transmitter transmits a frame responsively to a triggering signal from the triggering device. Further, steps for acquiring a display image during or after defect image acquisition by using, for example, a different defect image acquisition apparatus and a different imaging condition in accordance with preliminarily specified rules are added to an imaging sequence. The secret key consists of a number of bits of key information that are embedded within the photomasks used in manufacture the FPGA chip. The adjusting module is used to adjust gray-levels of the pixels according to the environment illumination.