A Design and Implementation of Full Digital QAM Demodulator
Wang Xiao-ya · Radio Engineering · 2010
Quadrature Amplitude Modulation (QAM) is a kind of modulation modes with high utilization ratio of frequency spectrum.In the paper,the influence of frequency offset and channel distortion on demodulator is analyzed.A design and implementation of full digital QAM demodulator is presented.The realization of timing synchronization is introduced in detail.A high performance cubic interpolation filter is adopted.The interpolation controller is a key unit,which decides the instant and the group of input data of interpolator.Symbol timing error is detected by Gardner Algorithm.The demodulator achieves high performance by using a joint architecture of carrier synchronization and equalization.The design is implemented in XILINX FPGA,and it can be applied to demodulation for communication or reconnaissance receiver.