Design Of Community Telephone Alarm System Based On DTMF Technology

Along with the social development and the growth of people's living level, the rise of residence community provides people with a more comfortable, convenient and efficient working and living environment. Home security has drawn more attention too. How to use modern communication and electronics technology to achieve unified management and control of community security system has become the most important issue to be resolved at this stage.This paper firstly analyzes domestic and international security alarm system status and according to the development trends, come up with a reliable and convenient intelligent community alarm system based on DTMF (Dual Tone Multi Frequency) technology using the telephone network, which meet the urgent demand of alarm timely at home and answering alarm at community center. The alarm system consists of user machine and center machine. User machine transmits the alarm information with the control of emergency button, center machine receives and identifies the calling number automatically, prompt the alarm information and help relevant scheduling. Center machine is connected to the computer, who has the function of database management, as well as the management of alarm telephone number of user machine through DTMF signal transmission.Community alarm system using the existing public telephone network, overcomes the drawbacks of conventional wiring arrangement; uses directional DTMF transceiver MT8880 and DTMF receiver HT9170 as the main devices of circuit to achieve the information exchange and interaction between home and community management center; uses serial port communication chip MAX232 to design the circuit of communication between center machine and computer; uses integrated circuit MC34018 to produce a high quality hands-free speaker-phone system for user machine, which can help residence converse to alarm center.In addition, center machine has connected to the alarm management system on computer, which is designed with friendly user interface in Chinese. Through the interface, it can realize the functions such as answering alarm, information inquire and the settings of alarm phone number of user machine.The signal of DTMF not only has the characteristic of strong anti-interference ability, far transmission distance, and low error rate, it also has the advantage of economical and practical, and convenient to popularize by using the existing public telephone network and saving the arrangement of wiring. The system is highly integrated, low cost, flexible functionality, and can be widely uses in residential, hotel, office buildings, warehouses and other important places.