Up/down frequency conversion method in EOC (Ethernet Over Coax) network

The invention discloses an up frequency conversion method in an EOC (Ethernet Over Coax) network. A code stream is mapped in constellation, up-sampled for N times, processed by a low-pass filtering, implemented with digital up-conversion and digital interpolation and converted by a digital analogue converter and finally output by means of the analogue signal. The invention further discloses a down-conversion method in EOC (Ethernet Over Coax) network; an analogue signal is converted by an analogue digital converter, processed by a digital sampling or interpolation part and a digital down converter, filtered by a low-pass filter, demodulated by a digital demodulator, and finally output as the code stream. In the invention, only a phase-locked loop with symbol rate is needed at the receiving end; the symbol rate is locked, and the carrier frequency is locked. The synchronous time is reduced by reducing one phase-locked loop, and the throughput rate of the system is increased.