DATA TRANSMISSION METHOD AND DATA TRANSMISSION DEVICE

摘要

A data transmission method for eliminating ingress noise of a LAN using a CATV system. A data transmission device (60) having an upper-layer cable modem (61) and a lower-layer cable modem (62) both connected in series is installed at the entrance of a network (50) in an apartment house. An upstream high-frequency modulated signal is converted to an Ethernet baseband signal by the lower-layer cable modem (62), which is modulated again by the upper-layer cable modem (61) and sent out. Since ingress noise is analog signals, it is eliminated by the conversion. Hence the data transmission quality is improved, a LAN cab be built even though the network is a network (50) in an apartment house involving much ingress noise.