This circuit is the use of digital encoding chips (such as the MC145026, PT2262 , etc.) for high-power transmitter modulation signal , which together with high sensitivity receiver and decoding and encoding chip matching circuit (such as the MC145027, PT2272 , etc.) for long-distance wireless Remote control, alarm and so on. The main technical parameters of the transmitter : FM system; operating frequency 36.1MHz; supply voltage 12V; transmit power 2 ~ 5W. The main technical parameters of the receiver : receiver frequency 36.1MHz; receiver sensitivity is not less than 1.5µV. Communication distance up to 5km. Figure (a) for the transmitter circuit ; receiver circuit shown in Figure (b) below .