A device that can regenerate or boost the signal strength in serial and parallel transmission so that you can use longer cables. Line boosters typically work with the RS-232 interface and can be used to increase the allowable distance between computers and peripherals (such as printers), usually doubling the distance from 15 meters to 30 meters for serial transmission and from 6 meters to 12 meters for parallel transmission.
Line boosters are needed in some networking environments because the signal strength in a serial transmission line decreases with the length of the cable being used.
Line boosters must be installed at the midway point between the computer and the peripheral, not at one end of the connection.
Graphic L-5. Line booster.