OFDM (Orthogonal Frequency Division Multiplexing) adaptive modulation system for EOC (Ethernet Over Coax) device

The invention discloses an OFDM (Orthogonal Frequency Division Multiplexing) adaptive modulation system for an EOC (Ethernet Over Coax) device. A receiving demodulation end channel quality estimation module is used for firstly estimating channel quality of a coaxial cable so as to obtain a channel frequency domain transmission function and a subband signal to noise ratio estimated value; then the subband signal to noise ratio estimated value obtained through estimation on the channel quality is sent to a modulation mode selection module, the modulation model selection module is used for comparing the subband signal to noise ratio estimated value with an ideal signal to noise ratio threshold to obtain a modulation mode, a modulation mode conversion module is used for converting next modulation mode according to the received modulation mode, and an adaptive modulator is used for carrying out corresponding modulation according to the mode value sent by the modulation mode conversion module so that the modulation