普通调幅信号电流的频谱和LC并联谐振回路阻抗的幅频特性和相频特性如图所示,则产生的普通调幅信号为( )。【图片】
A.
u AM = R e I sm [1 + m a cos( W t - p / 4)]cos w c t
B.
u AM = R e I sm (1 + m a cos W t )cos w c t
C.
u AM = R e I sm [1 + 0.707 m a cos( W t - p / 4)]cos w c t
D.
u AM = R e I sm (1 + 0.707 m a cos W t )cos w c t