Repeater
Repeater is also named as active hub operates at physical layer of OSI model. Repeater is an electronic device that simply regenerates the signal. Signals travelling through a physical wire travel some distance before they become week due to process of attenuation due to interfacing of other signals such as noise with them. For example a signal of 5v may become 4.5 in the process of transmission. A repeater senses with its intelligence and regenerates 5 v signals by recreating the bit pattern of original signal repeater is responsible for strengthening the signal.