Implementation of voice broadcasting systems using microcontrollers and SIP protocol

This paper presents our experience in using an 80 MHz microprocessor and the SIP protocol to implement a cost-effective network based broadcasting system. At present, broadcasting systems generally use personal computer to transmit voice signals to terminals device. Several processes are involved in a network based broadcasting system, including voice sampling, coding, compression, transmission, decompression, and so forth. The system performance is generally limited by the operation system. Delay time in previous approaches can be up to 2 seconds or 3 seconds. The system in our design aims at a delay less than 1 second. In our design, a PC is replaced by a low-cost microprocessor. Issues on delay and synchronization become more critical. These problems are resolved dedicate chip for audio processing and synchronization using sequence number field within RTP protocol.