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【简答题】
载波振荡的频率为f0=25 MHz，振幅为V0=4 V；调制信号为正弦波，频率为F=400 Hz；最大频移为△f=1 0 kHz。试分别写出：1)调频波和2)调相波的数学表示式。若调制频率变为2 kHz，所有其他参数不变，试写出3)调频波与4)调相波的数学表示式。
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