The populations of cars bring the convenience and happiness of living, but people are becoming more and more worried about the frequent loss of the cars. In this paper, a automobile security system is designed by adopting AT89C2051 and A7102C wireless transceiver. This system can use specific signal detecting means and support different alarming measure, which helps patrolmen and security guards quickly and correctly find the first crime evidence.

This article mainly from the start of the radio signal propagation characteristics, and connecting with the reality, according to the actual situation of some aera, the three typical environment of the topography for signal channel test and modeling is choosen. Through to the research of the zone VHF/UHF band, and a positive approach of the channel test and modeling are got.

Using RFID technology can significantly improve social efficiency, but the security of RFID systems is the biggest obstacle to its application. By analyzing flaws of fixed key mechanism in RFID systems, a simple algorithm of RFID dynamic key management is proposed. An experimental SCM system is designed to verify the algorithm. Experimental results show that the algorithm is safe, effective. The experimental RFID systems with proposed algorithm have the potential value of social promotion.