In this paper a QAM modem based on certain modifications of the CCITT
Recommendation V.29, is presented. A predominantly digital implementat
ion without the use of DSP devices is given. Although the implementati
on is for telephone bandwidth the idea can be expanded to be able to a
chieve higher rates. In this design approach the modulation is based o
n ROM-stored symbols while the demodulation is based on a symbol-by-sy
mbol determination for the recovery of the original information bits.
Specifically, the paper refers to a D16QAM design. Most of the stages
are digital, a feature that simplifies the VLSI implementation. The sy
nchronisation (timing recovery) is based on modified Phase Locked Loop
.