三gn(t)的付立叶变换 +1t>0 f(t)=sgn( t) 1t<0 e.t >0 f2()= t<0 F2()=-Je)a+∫e-m)h j20 2 2 C+0 F(o=lim F2(j@) >0 0 2 2 lim 1→0a-+JO o(j)=m<0 2三.sgn(t)的付立叶变换 f (t) = sgn(t) = +1 t>0 -1 t<0 f 2 (t) = .....  0 − e t at − e .....t  0 at F j e dt e dt a j t a j t    − + − − = − + 0 ( ) 0 ( ) 2 ( )    2 2 2   + − = a j ( ) ( ) 2 0 F j limF j a→ =     a j j a 2 2 2 2 0 lim = + − = →   2 F( j ) = ( j) = .... 0 2 −    .... 0 2    1 −1