Designing a PC-based real-time speech communication system

We present a low bit rate base band speech communication system by using the PC and Windows environment. The speech codec is the US DoD standard MELP with a bit rate of 2.4 kbps. This system is especially suitable for a channel transmission rate of less than 2.4 kbps environment. The system provides an RS-232 serial port interface for a normal modem as well as a TCP/IP interface for LAN. A Pentium 133 with a normal sound card is enough for such full duplex implementation.