11u(t)2 2sgn(t)根据傅里叶变换的积分特性没有偶次谐波。其频谱图如下图所示幅频图周期方波复指数函数形式频谱图-5 ω0-3 ω0φn-ω0-π/21-3求指数函数x(t) Aeat(a 0,t0)的频谱。解答:X(f)x(t)ee(a j2 f )tj2 ftdt Aeatej2 ftdt Ae(a j2 f)X(f)π/2ω03ω05ω0相频图Aa ...