In this thesis, we implement a V.22 voice-band full digital MODEM using general purpose digital signal processor(DSP) chip, and suggest efficient algorithms for V.32 9600 bps QAM modem.
The implementation is divided into three parts. The first one is a controller part which controls a flow between Data Terminal Equipment(DTE) and DSP chip. The second part is a data pump which receives and transmits digital signals with analog front end(AFE), and the third part is a Data Access Arrangement(DAA) which interfaces data pump with a real telephone line.
Algorithms for V.32 High Speed MODEM are suggested and tested. The MODEM algorithm implemented includes functional blocks of scrambler/descrambler, differential encoder/decoder, signal point mapper, pre-equalizer, band-pass filter, phase-splitter, timing recovery, carrier recovery, decision, adaptive equalizer, echo-canceller and hand-shaking.
For each functional blocks of V.32 modem, we choose passband symbol timing recovery, jointly T/2 spaced passband equalizer with carrier recovery and passband echo canceller with LMS algorithm for tap adaptation.
Designed MODEM is tested and verified through successful communications with a commercial modem. Increasing data rates upto 9.6 kbps, 14.4kbps and adopting V.42/V.42bis for error correction/data compression would be left as a further work.
