ctcss logic back to an external repeater controller I've been talking with a small number of people off the group about external repeater controller interface logic lines. In specific how many of the external repeater controllers handle ctcss (sub-tone, aka PL) detection, logic, control and selection.
To keep things short and simple... let us assume an example of the two most common repeater controller layouts regarding ctcss operation. Example 1. Simple external repeater controllers don't have any ctcss logic input lines. There is no software and hardware in place to address ctcss detection and control. Some folks do wire an available output logic line to toggle hardware within the repeater in and out of ctcss operation. But again the controller software in operation has no idea when ctcss is provided by the user. The controller only knows a command to drop or raise an output logic line has been requested. In some cases the controller software might label an output line as a ctcss on/off control function and even provide software "labels" to avoid confusion... Depending on the software within (and an available hardware logic input line) the controller, some people do wire ctcss logic detect. It's just a question of the controller software being able to respond in a usable format to valid ctcss detection logic and the creative programming of the repeater control operator/owner. Example 2. Many enhanced repeater controllers have a logic input line designed in software and hardware to be tied to the ctcss decoder output valid logic. With this type of hardware/software it is not a normally a requirement to provide a ctcss on/off control line back to the repeater hardware although an ordinary logic output line can be routed back to the repeater ctcss control hardware if desired and/or required. Software within the controller is often set up to respond to ctcss detection as desired and selected by the repeater control operator/ owner. Other creative programming allows the dtmf decoder to respond only to received signals with a valid ctcss in place. Macros can also be executed based on programming. Based on how creative you want to be... both repeater controller types can allow both carrier squelch and ctcss repeater operation. Some of the repeater to external controller modifications presented on the Internet include CTCSS detection logic output, which is not used with some of the more basic repeater controllers. One simply wires the basic repeater controller into place leaving the CTCSS detection logic input unused. Normally the repeater is wired to operate only in carrier or ctcss access but both modes are possible in most/many cases. Hot Java or Diet Pepsi help when you're trying to sort through the options. cheers, s.
