In this thesis work, we implement a 2400bps full duplex all digital MODEM algorithm in real time using a digital signal processor(DSP) chip for telephone channel voiceband data transmission. The channels for full duplex operation allocated by frequency division. The MODEM algorithm building blocks consist of symbol timing recovery, adaptive equalization, and carrier phase recovery. These algorithms are implemented in software and combined together to form a full duplex digital MODEM.
Before implementing the MODEM algorithm, we simulated the whole building blocks of MODEM algorithm and verify the algorithm. In the course of the simulation, we optimize the MODEM algorithm for DSP implementation. and then we test the implemented MODEM algorithm using a simple communication protocol for data transmission. The implemented MODEM algorithm conforms to the CCITT V.22bis standard.
In the implementation of the MODEM we use a TMS320C30 digital signal processor and the analog front end(AFE). The AFE consist of a bandpass filter, a variable gain unit, an analog to digital converter(ADC), a digital to analog converter(DAC), and a telephone line interface unit.
