A repeater frequency refers to both the input frequency (the frequency the repeater listens on) and the output frequency (the frequency the repeater transmits on). A repeater uses two frequencies to relay a signal over a wider area.
Essentially, a repeater is a device that receives a radio signal on one frequency and simultaneously retransmits it on another frequency. This allows users to communicate over longer distances than would be possible with direct radio-to-radio communication.
Input and Output Frequencies Explained
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Input Frequency: This is the frequency that the repeater listens on. Your radio transmits on this frequency when you are trying to access the repeater. It's often referred to as the "repeater input" or "receive frequency."
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Output Frequency: This is the frequency that the repeater transmits on. Your radio receives on this frequency when the repeater is transmitting. It's often referred to as the "repeater output" or "transmit frequency."
Why Use Different Frequencies?
Using different input and output frequencies is crucial for preventing self-interference. If the repeater transmitted on the same frequency it received on, its own strong transmission would drown out the weaker incoming signals. This separation allows the repeater to function effectively. This difference between the input and output frequency is commonly known as the "offset."
Example Scenario
Imagine a ham radio operator trying to talk to someone across a mountain range. Their radio's signal might not reach the other person directly. However, a repeater located on top of the mountain can help.
- The operator transmits on the repeater's input frequency (e.g., 146.22 MHz).
- The repeater receives this signal.
- Simultaneously, the repeater re-transmits the signal on its output frequency (e.g., 146.82 MHz).
- The other ham radio operator, listening on the repeater's output frequency, hears the message clearly.
Determining Repeater Frequencies
Repeater frequencies are typically published by local radio clubs, coordinating bodies, or online databases. It's essential to program both the input and output frequencies correctly into your radio to utilize a repeater effectively. Additionally, many repeaters require a specific CTCSS tone or DCS code for access.
