Design Scheme of Automobile SMS Anti-theft System Based on GPS-GSM

Abstract: In view of the current problems and market application prospects of automobile anti-theft equipment, the author proposes a new design scheme of automobile anti-theft system. The system consists of STC89C52 single-chip microcomputer, TC35i wireless communication module, XN934 + integrated GPS module, relay and other components. After testing, the system can monitor the car in real time, and its positioning accuracy is 5m, which realizes the anti-theft function of the car.

0 Preface

A large number of car theft cases occur in China every year. According to the statistics of Beijing Municipal Traffic Management Bureau, there were more than 10 car theft cases in Beijing in 2006, which seriously endangered the property safety of the people and the number of related cases in recent years It has risen sharply, and the means of committing crimes have been continuously upgraded. The activities of committing crimes have developed towards professionalism, intelligence and grouping. In view of the above situation, this paper designs a car anti-theft system based on the currently widely distributed GSM (Global System for Mobile CommunicaTION) network and high-precision GPS (NavigaTIon Satellite TIming and Ranging Global PosiTIon SySTem) positioning technology. Through the operation of sending and receiving short messages, real-time monitoring of the vehicle's position can be realized, helping the owner to manage the vehicle, and can effectively recover after the vehicle is stolen. The system has high sensitivity, good real-time performance, and the system has a simple structure and low cost.

1 Working principle of the system

As shown in Fig. 1, the system switches the communication between the microcontroller and the GPS module and the wireless communication module TC35i through the microcontroller control relay. When the owner does not need to monitor the vehicle, the serial port input of the single chip microcomputer is connected to the serial port output of the TC35i. When the owner leaves the vehicle, he manually drives the relay to pull in and connects the serial port input of the single-chip computer to the serial port output of the GPS. The system automatically collects GPS position data and starts real-time monitoring of the vehicle. When the system detects that there is a certain difference in the position information collected by the GPS module for two consecutive times, the relay restores the serial port input of the single-chip microcomputer and the serial port output of the TC35i, and sends a warning message "The vehicle is dangerous, currently located at longitude XX, latitude XX "to the owner.

Figure 1 System communication module block diagram

Figure 1 Block diagram of system communication module

2 System hardware composition

This system uses a single-chip microcomputer as a microprocessor, uses GPS module to collect the position information of the car, and then realizes real-time communication with the car owner through the wireless communication module. The composition of the hardware part of the system is as follows:

(1) STC89C52: This single-chip microcomputer has a low price, can complete the control tasks of this system, and has a high cost performance.

(2) TC35i wireless communication module: TC35i Siemens industrial GSM module is an industrial-grade GSM module that supports Chinese short messages. It works in the dual band of EGSM900 and GSM1800, and its data interface can transmit commands and data in both directions through AT commands, which can be well achieved Information transmission.

(3) Integrated GPS module: the XN934 series GPS module with model XN934 + is used, the operating voltage is 3.3V, the operating temperature is -40 ~ 85 ℃, the positioning accuracy is 5m, and its output interface is RS232, which can be directly connected to the single chip interface , And low energy consumption, small size, easy to integrate.

(4) Relay: Matsukawa small relay is used, and its contact form is three-open and three-close.

(5) Power supply: The system is powered by a 12V DC power supply, and the single chip microcomputer system and GPS module are powered by a voltage stabilizing system with a core of 7805.

The block diagram of the system hardware structure is shown in Figure 1.

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