Study and Implementation of Voice-bandCoded Modulation System

• Main Authors: Yu-Jen Ho, 何友仁
• Other Authors: Szu-Lin Su
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/zy5xhg

碩士 === 國立成功大學 === 電機工程學系碩博士班 === 90 === For data communication over the General Switch Telephone Network (GSTN), we use the quadrature-amplitude modulation (QAM) with echo canceller to implement the duplex modem in the voice-band. In order to attain better performance, we choose the Trellis-coded modulation (TCM) as error control code. The complex adaptive equalizer would overcome the problem of intersymbol interference (ISI) and using differential coding would avoid the phenomenon of phase ambiguous. In the other hand, Auto Gain Control (AGC), scrambler, Timing recovery, frequency recovery, carrier recovery, and Root Raised Cosine (RRC) filter are demanded for our system. The duplex modem is simulated by Signal Processing Work-system (SPW) and implemented by the TMS320C6711 DSK processor. The baud rate is 2.4 kHz with 9.6 kHz bps, and sampling rate is 28.8 kHz. The carrier frequency is 1.8 kHz in the system.