Communication system and master communication device and slave communication device

A communication system for communication through a human body, comprising:

• a master communication device, comprising:
• a first signal generator, generating a first signal;
• a second signal generator, generating a second signal;
• a signal combiner, combining the first signal with the second signal, so as to generate a third signal;
• and
• a transmitting HBC (Human Body Communication) electrode, transmitting the third signal through the human body;
• and
• a slave communication device, comprising:
• a receiving HBC electrode, receiving a mix signal from the human body, wherein the mix signal is related to the third signal;
• a signal splitter, dividing the mix signal into a data signal and a synchronization signal;
• a processor, processing the data signal;
• and
• an injected-locked DCO (Digital Control Oscillator), performing a time synchronization process according to the synchronization signal;
• wherein both the first signal and the data signal fall within a first frequency band from 2 MHz to 80 MHz;
• wherein both the second signal and the synchronization signal fall within a second frequency band from 80 MHz to 102 MHz.