Performance evaluation of 1024 QAM signal transmission in cable television distribution systems by software demodulation method

1024 QAM transmission characteristics in cable television distribution system is experimentally evaluated. 52.74 Mbps transmission in a 6 MHz cable television channel is achieved. Spectrum efficiency is 8.79 bit/s/Hz. The transmission performance on a 1024 QAM modem with high amplitude density and large capacity is demonstrated. MPEG-2 TS packets are derived by demodulation software from the IF signal received in a PC-based memory. Experimental result shows that the BER of 1024 QAM transmission without forward error correction is 10^-4 at a CN ratio of 38 dB. The implementation loss is less than 2 dB. Furthermore, the distortion effect induced on a 1024 QAM in the presence of a non-linear amplifier is also discussed.