第7章2單位脈沖函數(shù)-全文預(yù)覽
【正文】 ?0ite? 2?? 0()?? ??F[ ] 14i?22()i t i tee ??()ftF[ ] 1 {4i? 2ite 2ite ??1 [4i? 2? ()2?? ? ?? 2( ) ]?? ?2i?? [ ( )2?? ?( ) ]2????11 119頁例 證明 的傅氏變換為 ()Ht????0 0t ?0t ?1 t()Ht101i? ()?? ??證 12?()ft ? d?????? ()F ?tie?已知 ()F ? ?1i? ()?? ?? 則 1i?tie? ()?? ? tie?12?????? ? d? ?單位階躍函數(shù) 12??????d?cosit?? ?sin t??12?????? ? d? 12? ????? d?12?1?? 0????sin t? d? 12?????0t ?00t ?1()Ht?()t? ()ftdt????? (0)f?12 3[]練習(xí) 求函數(shù) 的傅氏變換 ()ft 3(sin )t?解 ()ft 12i? ( ite )ite??8i?3( ite 3 ite? 3 ite?? 3 )ite??F[ ] F[ ] ()ftF[ ] {8i? 3ite 3 ite? 3 ite ?? F[ ] F[ ]} 3ite ??0ite? 2?? 0()?? ??F[ ] 4i?? [ ( )3?? ? 13 ( )???? 13 ( )???? ( ) ]3????13 例 3 求函數(shù) 的傅氏變換 ()ft s i n ( 5 )3t ???解 ()ft0ite? 2?? 0()?? ??F[ ] 12i?3 )5([ ite??3()5 ]ite????14i?5[ ( 1 3 ) itie? 5( 1 3 ) ]itie ???F[ ] ()ftF[ ] 1 {( 1 3 )4 ii?? 5ite ( 1 3 )i?? 5ite?F[ ]} [( 1 3 )2 ii??? ()5?? ? ( 1 3 )i?? 5( )]?? ?12i? 5[ ite 3ie?? 5ite?? 3 ]ie???14 傅氏變換的物理意義 —— 頻譜 1()n
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