Block diagram of remote controller system.

The main principle of offered system operation has been shown above. The central unit of this system is PIC based remote control circuit which will be called as controller. This controller detects the number of ringing, then decodes DTMF signal and then checks pin numbers which are entered. When the pin numbers have been entered correctly, the controller gives to right to control devices. Both pin numbers and orders to control appliance have been transmitted via telephone line or electromagnetic waves as DTMF signal.