Design of Alarm System Based on SMS

An alarm system,which is based on SMS and controlled by P89C58,is introduced.According to ultrasonic’s Doppler effect,the ultrasonic T/R head is utilized to make an intruder alarm.When somebody gets into the car illegally,the alarm system,which is installed inside the car,begins to work and sends a message to tell the owner of the car that someone has got into the car.This article is elaborated emphasis on hardware design and software programming of SMS transceiver.The advantages and shortcomings are analyzed too.