4.2 Frequency-Domain Representation of Sampling 单位冲激串的傅立叶变换：S2)-2平∑δ2-k2) T:sample period;fs=1/T:sample rate;s-2/T:sample rate s()为单位冲激串函数，可展开傅立叶级数 sG∑ot-n0=之aenr=72e2w s(t) tycoidi- Is() ejkS2stF→2π6(S2-k2s) 2π +S(j2) sU0)2平∑s0-k2) 2π 2π T T 55 T：sample period; fs=1/T:sample rate;Ωs=2π/T:sample rate ( ) ( ) n s t t nT   =− = −  ( ) ( ) 2 s k S j k T    =−  = −   ( ) ( ) 2 s k S j k T    =−  = −   k k a e jk ts  =−  = s(t)为单位冲激串函数，可展开傅立叶级数 1 k s jk t T e  =−  =  2 ( ) F s jk ts e  k  → −  -T 1 t 0 T s t( ) … … / 2 / 2 ( ) 1 1 s T jk t k T a e dt T T  t + −  − = =   0 S j ( )  … … 2 T  2 T 2  T  − 单位冲激串的傅立叶变换： 4.2 Frequency-Domain Representation of Sampling s t( )