repeater
termnetworking
A radio station on high ground that receives on one frequency and simultaneously retransmits on another, extending the range of low-power stations.
Two settings catch newcomers out. The offset is the difference between the repeater's input and output frequencies, and reversing it means you hear everyone while nobody hears you. CTCSS is a sub-audible tone proving you are a legitimate user rather than distant interference, so the right frequency with the wrong tone produces the same silence as the wrong frequency. Repeaters are almost always built, sited, and maintained by volunteers at their own expense.
Also known as: CTCSS, offset, duplex