In the first stage, the amplitude sequence of modulating signal is generated by addressing waveform memory and added by the frequency value of carrier wave in the adder. The parallel output of the adder is served as the frequency control word of the second phase accumulator. 在第一级寻址结构中产生的调制信号幅度序列和载波频率值在加法器中相加,并将相加的结果作为第二级相位累加器的频率控制字;