实信号的频谱为什么是共轭对称的

Posted 2022-09-09 者乎之类的

Under which of the following conditions, the real part of a signal is guaranteed to include all the information of a complex signal:
(a) the spectrum is non-zero only on negative frequencies
(b) the spectral support is symmetric around zero
© real part of the spectrum is symmetric and imaginary part is antisymmetric
(d) the imaginary part of the spectrum is zero
答案ac.
其中c这样的复信号就是纯实信号。