26 lines
1.3 KiB
Markdown
26 lines
1.3 KiB
Markdown
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tags: [radio, ham-study]
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---
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Repeaters exist in order to extend the range of mobile stations. They are
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designed to solve the line-of-sight problem associated with VHF/UHF, receiving
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your signal and re-transmitting it at much higher power, extending the range of
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low-powered portable devices.
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Repeaters **have an input and output frequency** so that they can receive and
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transmit at the same time. On VHF, repeaters typically transmit at 600KHz above
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their input (receiver) frequency. The difference between the transmitting and
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receiving frequency is known as the "offset".
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In order that the repeater can distinguish intentional communication from noise,
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it will use CTCSS tones. These are non-audible low-frequency tones that are
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transmitted along with your audio. The repeater will only activate if it "hears"
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the right tone. You have to program your radio to transmit the right CTCSS tone
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for the specific repeater. In the UK there are 9 blocks of tones.
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> It is important that you do not use the calling frequency of a repeater for
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> normal two-way communication (simplex). This would prevent people from using
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> the repeater. When you are agreeing on a shared frequency for CQ, ensure you
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> are not accidentally using a repeater frequency. The repeater frequency (and
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> its offsets) should only be used for repeater-relayed communication.
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