RF modules are small, low-cost devices designed to transmit and receive radio signals between two points. They are widely used in wireless communication applications such as Remote Control, Automation or Surveillance systems. Most RF modules have their own microcontroller and are pre-programmed with a transmitted frequency. The user can program the device by sending instructions to it via a serial port, RF chip, or even an LED. Once programmed, they can send out a signal and be used to communicate with other RF modules within their signal range.