A repeater re-transmits (“repeats”) a 2-way radio transmission, typically at a higher power and through an elevated antenna. This allows anyone who can reach the repeater with their radio to talk to anyone else who can also reach the repeater, even if the two radios are too far apart to directly communicate with each other. It also enables 2-way radios to better communicate around or through obstacles such as terrain, infrastructure and foliage that may block direct radio-to-radio signals as depicted above.

Currently, the Newport County Island project is not using any specific permanent GMRS repeater.   There are at least two portable repeaters  available for local use, when needed.  Recently operating repeaters include: 

Using a repeater requires a 2-way radio that is “repeater-capable.” GMRS radios noted here are all repeater-capable and will work with the gen4AI repeaters when the radio is properly configured.  Contact us for help configuring your repeater-capable GMRS radio to work with  gen4AI.   

Currently, gen4AI is primarily using direct radio-to-radio (called “simplex”) transmissions on FRS/GMRS Channel 3 (462.6125 MHz). Should there be an "event," Channel 3 functions as the main information channel. Other channels are likely to be established to handle more specialized communications as the situation unfolds. 

Technical Notes About CTCSS/PL Tones and DCS Codes

Most 2-way GMRS radios can be configured to include a sub-audible “tone” or digital code that is added to the transmission. They can also be configured to only receive signals that include that same sub-audible tone or code, and ignore everything else. These are called CTCSS/PL tones and DCS codes. These omni-present tones are barely audible to the human ear but the radio receiver hears them and can react to the specific audio frequency or digital code.

The repeater as well can include the same tone or code on its output, allowing receiving radios to ignore other signals that don’t come from the repeater. And, repeaters can be configured to only re-transmit signals that include a specific tone or code, and ignore everything else.

At this stage, our portable repeaters will be listening for a specific CTCSS/PL tone from radios in the field. If that specific tone is heard, then the repeater will rebroadcast your transmission.  If the correct tone is not heard, then your transmission will be ignored by the repeater.

CTCSS stands for “Continuous Tone-Coded Squelch System”, commonly known as “PL Tones” from the Motorola trademark “Private Line”. That’s a misnomer, as discussed below. CTCSS/PL tones are sub-audible (below the range of human hearing), usually between 67 and 257 Hz. Even though we can’t hear them, the repeater and radio can, and can “open the squelch” (hear the transmission) when the proper tone is present. Again, this allows the repeater to only repeat signals with the proper tone, and receiving radios to only hear signals that include the proper tone.

DCS (Digital Code Squelch) codes are a similar concept to CTCSS/PL tones, except that a binary data stream is passed as sub-audible data along with the transmission. It serves the same purpose to filter out unwanted transmissions and receptions.

CTCSS/PL tones and DCS codes can be confusing since they are often marketed as “privacy codes.” But adding a tone to your transmission doesn’t actually prevent others from hearing your transmission. Rather, it allows others to filter out other signals if they wish to, and only hear your signal. Anyone can configure their radio to not filter for tones on receive (setting PL to 0 or “Off”), in which case they will hear ALL transmissions on that frequency, regardless of whether or not they include a tone or code. No GMRS transmissions are truly private.

A reference on demystifying CTCSS/PL tones and DCS codes can be found here.   If still confused, just send us an email at gmrs@W1SYE.org