The Design And Realization O The Small Digital Program Controlled Exchange

In recent years the communicating technology has advanced rapidly in our country. The telephone network based on circuit-switching and digital program controlled exchanging technology plays an important role in the whole communicating networks. The text firstly introduces the status of the program controlled exchange, and compares simulative exchange with digital exchange in the performance, and points out the developing direction of the future digitalexchange. Then the text describes the principle of the pivotal technique-Pulse Code Modulation (PCM) in detail which realizes the conversion of the exchange from simulation to digital. The third chapter introduces the hardware and analyzes the primary function modules with the function diagrams, and illuminates the uses and the interface with the singlechip of the special chips such as audio processing circuit AM79C03, digital switch MT8980 and so on. The difficulties of the text are the use of the integrated DTMF receiver MT8870 and the signal generator circuit. Their realities need occupy the PCM timeslots. They are the characters of the digital program controlled exchange. The forth chapter is the software design which deals with the telephone call between the users and implements the transfer of their voices.The text provides the detailed program flow , and completes the research and the hardware design of the digital program controlled exchange in local area network.