Quick Answer
GMRS radios operate within the 462-467 MHz and 467-472 MHz frequency ranges for simplex communication, with repeater frequencies typically in the 467-470 MHz range.
GMRS Frequency Bands
The General Mobile Radio Service (GMRS) operates on a shared frequency band, with the US Federal Communications Commission (FCC) assigning frequencies between 462-467 MHz and 467-470 MHz for simplex communication. These frequencies are divided into 30 channels, each 12.5 kHz wide, with a maximum power output of 50 watts. This allows for local communication within a 50-mile radius, depending on terrain and antenna gain.
GMRS Repeater Frequencies
For longer-range communication, GMRS repeaters are used to amplify and retransmit signals. Repeater frequencies typically fall within the 467-470 MHz range, with the receive frequency typically 5 MHz lower than the transmit frequency. For example, a repeater with a receive frequency of 467.925 MHz will transmit on 472.925 MHz. This allows users to communicate with repeaters that are many miles away, increasing the effective range of the GMRS system.
Interference and Channel Selection
When selecting a GMRS frequency, it’s essential to avoid interference from other users and nearby repeaters. Using a frequency analyzer or scanning the channels can help identify available frequencies. Additionally, using a directional antenna and keeping the antenna at least 20 feet above ground can help minimize interference and improve signal strength.
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