[AM signals' digital demodulation and its application in physiological signals' remote transmission]

Taking advantage of the characteristics of digital systems, a new digital method is given in this article to overcome the difficulties in demodulating AM signals using digital methods. Physiological signals can't be transmitted through telephone networks because they are full of ultra-low frequency components. However, if they are modulated (such as AM), they can be transmitted to the receiving end through telephone networks. Then phaselocked loops can be employed to trace the frequency of the signals' carriers so that we can demodulate and transmit them in the end.