Basic general cables are adequate for tasks like DC or low-frequency AC signals transmission. However, the N type connector (being screw-down tightened) and the C type connector (being bayonet locked) are invented to minimize signal reflection and stationary wave interference when it comes to high-frequency (RF) signals. Although both of them occupied a certain market share at that time, neither is the ideal one. The profile of the N type is thinner than that of the C type with complicated manufacture processes while the C type can be quickly on-and-off with a plump size. Therefore, the Ethernet over BNC arises combined with the former two's advantages.
The Ethernet over BNC adopted by our television industry is primarily to connect 50 ohms and 75 ohms of coaxial cable. The 50 ohms are used chiefly for radio and antennas of transmitters, Wi-Fi , GPS, cell phones and duplex while the 75 ohms are applied mainly for video cables, receivers of satellite and cable TV and police scanners, etc.. Compared with the 50 ohms, the 75 ohms is more accurate (The 93 ohms is theoretically the best for transmission, but 75 ohms is more feasible given the overall cost) . In addition, a mixture of the 75 ohms and the 50 ohms or different connectors can result in signal chaos with about 5% of the effective signal lost per mix-up.