Research On PSTN-based Elevator Security Telephone System

With large emergence of the high-rise, the elevator has become an indispensable traffic tools for going up and down in the buildings, and applied extensively in the cities. More and more social public and media have paid much attention to how to assure the elevator runs reliably and the safety of passengers. In the market, most of the Elevator Security Telephone System made use of the intercommunication mode, although it has the characteristic of simple wire layout, convenient wiring, flexible extension and lower cost. In the mean time, it has the problems of bad communication pertinence, poor quality, can not keeping secret, simple structure, simple function, and can not meet the demand of Security Telephone System's development market. So, there are requirements to develop a new Elevator Security Telephone System which has the characteristic of strong pertinence, perfect communication quality, and powerful function.This article is based on analyzing the same product's market need and dynamic development, benefiting from the merit of relevant product, develops the elevator security telephone system based on PSTN with Ningbo electronic equipment factory. The system adopts the bus topological structure and employs DTMF as the system's signal, organizes the elevator group as a network, makes up of the community Elevator Security Telephone System which is constituted by elevator extension,central room telephone and the community's manage host computer. Make the most of the public switching telephone network which is almost covered everywhere as the medium, then proceed to the next step bring the Elevator Security Telephone System into City Elevator Security Administration System, achieve the function of elevator centralized monitor and control, remote monitor, multiple path alarm.This article firstly introduces the foundation of the elevator security telephone system'model, the realization of the communication protocol and various system signals, on the basis of these the article also introduces the detailed structure characteristic of the system and the main working process; In the mean time, the article describes the detailed design blue print of the system's hardware and software; and in the end we debug and analyze the reliability of the system to make sure the design achieves the goals.The design of the system is flexible, according to the need of client, can connect to the centre of remote elevator monitor through public switching telephone network, or just intercommunication. The project has the characteristic of simple wire layout, convenient use and maintenance, perfect communication quality, preferable dependability and security, can meet the demand the market'need, easily spread. Further more, this system can replace the telephone system which is used in hospital, army and hotel. At present, the system has passed the debug in the laboratory, and will be applied in product.