Study On Doppler-type Microwave Alarm System

With the rapid development of communication technique and great improvement of standard of people's living, the need of house has been changed from only the living space to multiform needs of quality, function, service, and so on. It is necessary to design theft-proof alarm system which is valuable for protecting people's possession. A kind of microwave theft-proof alarm system for residential area is introduced.According to Doppler Effect, microwave detector is designed. It put forward the design methods of oscillator based on the RF transistor which work at the characteristic frequency. It design preamplifier based on the principle of positive feedback. It is possible to set alarm automatically by micro-controller and other chips. When the sensor of burglarproof detects any off normal signal, an interrupt request is sent to the MCU. Next the MCU control the interface module of telephone to accomplish off hook. According the kind of dangerous, the dialing module will automatically dial the right phone number such as the phone number of the users set up in advance.The alarm system is subdivided into eight parts including microwave detector, microcontroller, automatic dialing circuit, voice circuit, man-machine interface circuit, telephone interface circuit, alarm information collecting circuit and power circuit. This dissertation describes the design of hardware of the alarm in detail, in which selecting suitable chips, periphery circuit, chips interface. Moreover, it is described the software design diagram of the alarm system's main program and automatic alarm subroutine.According to the requirements of the subject, the microwave alarm system is satisfied for the basic needs of users. It is discussed the development trend of security alarm system in the end.