What is a Repeater?

GMRS Radio Range ... And How Repeaters Boost Range

The range of  GMRS radios can reach up to 35 miles in ideal line-of-sight conditions (like peak-to-peak or peak-to-valley), but many of us use radios in more complex terrain, including urban type settings with may obstacles like buildings. One of the biggest advantages of GMRS radios is access to repeaters, which extend or boost range when terrain blocks direct radio signals. 

Repeater Basics

You can think of a repeater like another radio that retransmits your message to reach other radio users in the area. Repeaters are typically placed at high points, like on an existing tower, hill, or mountain peak, to help overcome terrain obstacles, like a ridgeline or dense urban areas.

In the image on the left, with normal radio-to-radio communication, the transmitting radio on the ground can only connect with radios that have a clear line of sight. In the image on the right, accessing a repeater at a high point overcomes the terrain so you can communicate beyond the hill and peak obstructions and make a connection. (image complements of the Rocky Talkie blog)

When using repeaters, you can only communicate with radios that are also using the same repeater. You cannot have radio-to-radio communication with radios that are not using the repeater. To reestablish communication with radios not using the repeater, you need to switch back to non-repeater channels. It's also worth keeping in mind that your radio still needs to be within range of the repeater itself to make initial contact, so while a repeater can substantially boost your coverage, placement and proximity to the repeater still matter.

Let’s say you purchased a couple of GMRS radios for use in the Butler Hill Precinct for emergency situations. We know (from actual tests) that communication to and from any point within the precinct is possible. But suppose you have family or friends who live in other parts of the valley, and you can’t reach them on one of the standard 22 GMRS channels due to the urban interference. Repeaters may be a solution.

If you are interested in setting up your GMRS radio to use local repeaters, contact Steve Neidig (butlerhillprecinct@gmail.com).