TMC21 - FM Modulator

It is a Digital FM Modulator and control board which used inside ONAIR brand FM transmitters. 

It has Left&Right XLR analog audio inputs, XLR AES/EBU digital audio input, built-in RDS encoder, DB9 I/O connector for coaxial switch, on board Raspberry PI connection connector, 2xCVS18 current and voltage sampling board connector, LCD display connector, AC input connector, ON/OFF connector and 8 dBm SMA RF output power connector.

It has built-in PWM and Op-Amp with adjustable gain to obtain 0-11V Driving Control Voltage. A remote on/off pin helps Power Supply unit becoming on and off.

It has ADC input connector for forward power, reflected power, amplifier module 1&2 RF powers, input RF power, heatsink temperature. It also measures amplifier voltage and Driving Control Voltage.

By means of measurements available protections: VSWR, Over Temperature, Over Amplifier Voltage, Over Driving Control Voltage, Over Current, Unbalance.

With the connection of LCD display (2x16 char LCD with 3v3 supply) all parameters can be monitored and controlled.

Deviation of Left&Right XLR analog audio is adjustable from LCD and remote control.

With Raspberry Pi board connection it is possible to get I2S audio which is able to play IP audio and Integrated Media from SD card of Raspberry Pi.

Raspberry Pi allows user to control device remotely over IP based web server and cloud (osc.onair.com.tr).

With the help of trimmers on the board(POTS-21) it can be calibrated with all kind of transmitters: (FWD, REF, Amplifier Module 1&2, Input Power, Current 1&2 -- Gain of Op-Amp)

Built-in RTC module store the real-time so Events are recorded with real-time -- Necessary to put 3V battery on TMC21 board. These events are sent to cloud so in case of alarm or event user will be notified with e-mail if user registered to osc.onair.com.tr.

Integrated control system of redundancy offers 1+1 change-over system. Coaxial switch or relay should be connected to DB9 coaxial switch connector.

It is necessary to buy a LCD&Key unit to use in special applications to control TMC21.