|  | 9.7 | Range of Equipment for Testing Structured Cabling Projects
| 9.7.9 | Signal attenuation

Various factors can reduce the power of a signal as it passes through the copper wires used in UTP cables. This reduction in the power of a signal is called attenuation. It occurs because a signal loses energy to a cable. A cable tester can measure the reduction in power of a signal received from a device known as a signal injector - a small box, approximately the size of a deck of playing cards, attached to the far end of a cable. Cable testers generally measure attenuation at several frequencies. Cable testers for CAT 5 cable generally measure up to 100 MHz. Check the TIA/EIA-568-A specifications to see what amount of loss is allowed for the type of cable used in your LAN.

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