In the movie "Pump Up the Volume," Christian Slater plays a DJ operating an amateur radio channel from a ham radio setup in his home, and chances are that he used a repeater to get his message across to the town's teenagers. There are two standard types of this tool: a UHF repeater and a VHF repeater. What do these devices do, exactly? A repeater receives the transmission of the signal, then amplifies and strengthens it without lessening the sound itself. This means that the sound can travel long distances without compromising sound quality in the process. While amateurs frequently use these devices, found on eBay from reliable sellers, police and fire personnel also use them for the same reason, though their equipment is typically more sophisticated. Additionally, walkie-talkies used by emergency personnel come equipped with them as well, and their power comes from many sources, including batteres or generators. Make your voice heard when you use a repeater to transmit a signal.