ONAIR FTC-DT model FM transmitters feature a built-in N+1 redundancy system, eliminating the need for an external automatic changeover unit. Coaxial switches are directly connected to the transmitters, streamlining the system architecture and enhancing reliability. MC-17 is a dedicated RS485 master controller designed to manage communication across an N+1 transmitting system. It ensures orderly access to the RS485 bus using a Time Division Multiple Access (TDMA) protocol.