Simulation on the implementation loss of 1024 QAM modem in cable TV systems

Abstract

Feasibility study on the higher capacity modem for cable distribution was conducted. The modulation scheme was based on the quadrature amplitude modulation(QAM)as defined in the ITU-T Rec. J. 83. The calculation of BER for the higher speed modem was made by increasing the number of the quantized amplitude level for each symbol. Implementation loss due to the carrier phase error and symbol decision timing phase error was evaluated. The simulation results show the relationship between the two kinds of errors and the BER performance of 1024 QAM modem in numerical order. Also, the results can be used to cstimate the system margin for the implementation of the high-speed 50Mbps(10bits/symbol)modem on cable TV 6 MHz channel.