The system implementation of I-phone hardware by using low bit rate speech coding
This paper presents a system implementation for Internet-phone communication with real-time speech coding schemes. A low-cost speech processing coprocessor is embedded. A CPLD device is used to implement the interface between the host processor and the coprocessor via conventional parallel port. At the headphone interface, there are a 16-bits PCM CODEC and an audio amplifier with acoustic echo cancellation features employed. The system consists of a mixed implementation of software and hardware. The experimental coding rate is 8.5 kbps. In such rate, a 14.4 kbps or higher speed modem can conform to offer full-duplex speech for the applications such as digital simultaneous voice data (DSVD).