Underground power supply communication signal transmitting and receiving system

The invention discloses an underground power supply communication signal transmitting and receiving system which comprises a data forwarding module, a downlink data analysis and recombination frame module, a local execution module, a direct current carrier modulation module, a step-down rectification filtering module, a modulatable direct current power output and data processing module, a direct current carrier demodulation module and an uplink data analysis and recombination frame module. When downlink data are sent, the direct current carrier modulation module carries out frequency shift keying modulation on a terminal data frame transmitted by the downlink data analysis and recombination frame module, and the modulatable direct current power output and data processing module loads a modulated signal to a direct current source to carry out underground communication; and when uplink data are received, whether an uplink direct current carrier signal is received or not is judged by detecting and verifying a da