How Does Signal Relay Work?

- Jun 08, 2018-

How does Signal Relay work?


Signal Relay DPDT.jpgA signal relay is a device that connects network lines and is often used for bidirectional forwarding of physical signals between two network nodes. The signal relay mainly completes the functions of the physical layer and is responsible for bit-by-bit transmission of information at the physical layers of the two nodes, completing the functions of signal duplication, adjustment, and amplification, thereby extending the length of the network. Due to the loss, the power of the signal transmitted on the line will be gradually attenuated, and the signal will be distorted when attenuated to a certain degree, which may cause reception errors. The repeater is designed to solve this problem. It completes the connection of the physical line and amplifies the attenuated signal and remains the same as the original data. Under normal circumstances, both ends of the signal relay are connected to the same media, but some repeaters can also complete the transfer work of different media. In theory, the use of repeaters is infinite, and the network can therefore be extended indefinitely. In fact, this is not possible because the network standards all specify the delay range of the signal. The signal relay can only perform effective work within this specified range, otherwise it will cause network failure.

The signal relay can connect two LAN cables, re-timing and regenerating the digital signals on the cable, and then send them out. These functions are typical functions of the physical layer in the first layer of the OSI model. The role of the repeater is to increase the coverage area of the LAN. For example, the Ethernet standard stipulates that the maximum length of a single-segment signal transmission cable is 500 meters. However, after using a signal relay to connect the four-segment cable, the signal transmission cable in Ethernet can be the longest. Up to 2000 meters. Some brands of signal relays can connect cable segments of different physical media, such as thin coaxial cables and fiber optic cables.


Due to transmission line noise, a digital or analog signal carrying information can only transmit a limited distance. The function of the signal relay is to reproduce and transmit the received signal, thereby increasing the distance of signal transmission. It connects two or more network segments of the same network. The signal relay only sends the data on any cable segment to another cable, regardless of whether the data contains incorrect data or is not suitable for the network segment data.