If the repeater is operated by an amateur radio club, you could look up this information on the club’s website. How do you know what CTCSS tone you need to access a particular repeater? Well, one way to do this would be to check a repeater directory. If the two repeaters use different CTCSS tones, however, this is not a possiblity. Although care is often taken to minimize this interference, sometimes long-distance propagation can cause stations accessing a repeater to also access one many miles away. If a sub-audible tone is required, however, the repeater will remain off until it hears a signal that was definitely meant to be repeated.Īnother reason for using CTCSS tones is to prevent interference from other repeaters that use the same repeater frequency pair. In such an environment, the generation of spurious signals could cause the repeater to think it’s receiving a signal on its input frequency and turn on its transmitter. On a tower or rooftop, for example, there may be several repeaters, a paging system, and other RF equipment. Why do we use CTCSS tones? One of the reasons repeaters use CTCSS tones is that they often operate in environments where there is a lot of interference.

So, even though your radio may be transmitting and receiving on the correct frequencies for a particular repeater, you won’t be able to access the repeater if you’re not also transmitting the CTCSS tone the repeater has been programmed to respond to. The signals that a repeater (or radio) will receive are signals with a specific sub-audible tone, called a CTCSS tone, that has been added to the signal.

The repeater may require a proper DCS tone from your transceiverĬTCSS stands for continuous, tone-coded squelch system, and is a technique used to allow repeaters-and radios-to receive particular signals and reject others.

The repeater may require a proper CTCSS tone from your transceiver.QUESTION: Which of the following could be the reason you are unable to access a repeater whose output you can hear? There’s even a question on the Technician Class exam that addresses this issue, question T2B04: One of the things that many newcomers to FM and repeater operation fail to do when programming a radio is to program the CTCSS tone properly.

Tpl squelch chirp programming