Abstract
1024 QAM in a 6 MHz cable TV channel, higher spectrum efficiency than conventional 64 or 256 QAM modem, is demonstrated. 5.274 M symbol/s, 10 bit/symbol, i.e. 52.74 Mbps MPEG-2 TS packet transmission with a single carrier is achieved. Channel coding format is compliant with ITU-T Rec. J.83 Annex C.Demodulation by software is separately processed from the real-time IF signal reception. The demodulation software contains the following function : orthogonal detection, 128 tap FIR roll-off filtering, frequency estimation, channel equalization, de-interleaver, shortened RS(204,188)forward error correction code and energy dispersal removal. We evaluate the 1024 QAM transmission characteristics for cable TV distribution. Experimental results show that BER performance of 1024 QAM without FEC is 1×10^<-4> at the CN ratio of 38 dB. Implementation loss is less than 2 dB. This transmission scheme is applicable to cable modem or digital contents distribution.
