一个连续信号含两个频率分量，经采样得 ，已知N=16,△f分别为1/16和1/64，观察其频谱 当N=128时,△f不变，其结果有何不同，为什么？-A continuous signal with two frequency components, by sampling a known N = 16, △ f, respectively, for 1/16 and 1/64, to observe its spectrum when N = 128 hours, △ f the same, t