求图 3-17 所示信号的频谱函数。[br][/br][img=278x235]17a33469f9c0a5d.png[/img]
解 解法一 [tex=4.429x1.429]7wP88YFRrLQSGJdxsSsC01fJn9C2rOzcVU57NcSaIz+x1BtfGG75MIqYBtu4AjEX[/tex] 的波形如图 3-18( a ),( b ) 所示。利用傅里叶变换的时域微积分性质求解。[img=531x293]17a3348a7978562.png[/img][tex=22.857x5.214]a0s3MH7cLIdmiBRR0YN06+rQT8dv1wqRetfw3BtOjz7A94hEQYXOHbMSv9ocV+CMGXMQBipcAqGgir/6GigzG4A9XU0qftftOAu/e9m84qALHTHfYkOB+dAQfMQrIaGn9tle9iM/b1DuLrIZtjn5Uq3CtsKXcPFzF4+zMSynQUN2llh1/Q7AuGCk+GqggDDaOVxaaZjzQGLt5QKmGPKGB/S3IXVEntJycZepzJGZVRTDYOGfVJXyPFxs094D6C1jbNIZfvi/xfJqW/1gmlC97BIWj6qQxW9WwVQZLmNd+RUDAnI4NTAOYCIvWC+u4W4Z/uBSLJVxoATl6pz4+uXMXMF+TQ7njlQDXpwjw7VicKYiJnqB8zZOdKWHrXSBn8GZ9X8UdDpNw5APzXFYoMRtrnoNXKn5cRx4/Uaf+kinnMroaTA0zqdND+Zij8qJL1Pl[/tex]显然 [tex=4.571x1.429]lbT1PPZWcSbNEv45cVpXhPd4akqzyNfzc+AmK4LkioI=[/tex], 因此[p=align:center][tex=29.571x2.786]GAfTgVt2kx+QJln4jWKy8or8AqhmdfK4O/0SCtG9aAobdLiYzpk4oj+iRtqfkU+NNGVgbLiOAD3qmyaLhNQIl3WuNH9QOO7fdRshRbRCSf8mgvpJuAFlm0AMZh7SPA1t+oCPnECQKHbEYjYxWp+xIJF0ylEcJcT9qVSAdkz062Ecjbi8pIl2NulQCytEASifzBZW+yNOPJLt9y8pq5+SM9rMrYfQ99amIT2WqGDLH6Qy8qNw4SRTGDWVzzjKPKlxO05tqyeBWLyilZ8Iewd1vQ==[/tex]解法二 用叠加性质求解。[p=align:center][tex=12.714x2.786]kZz+MqmLZhriE+aTlKaP3Y3UFCU1/R4IIa2fwMOsR027qhsSHzLzUAnKEzigD9BWVo1jPkBAVhYcooWY0sW+YqCqeEuXWs99m3oGK7tA+ec=[/tex]因为 [tex=23.643x2.786]NPrWLSyU0971TiifT6ehXc/qzS0uJF7HKH+U4RFUreON8jAPS0yI08pmpQFNAjGz8IhscD2+5ev+mn3gQB5jUTS+3sQZ1qg4EVu3EEr9Ie6Xf1a6aSd+DKaK8RATD2e4chUOMNhUv3irPqByAjwoNs62JUk66QXZZCqM/hPJw5cRcfhcrjBa5PG5cpJ1FUIIwWKBxi9mCS+lmgIpdnwE7pvFvAwIm9W1N94sSWCMICepwxTLWbqCUZ3YKY+72Z3c[/tex]所以 [tex=12.714x2.214]WZfveWkiWEEOr3rzmdE+NBDFGv32ZivmURKcYLpIFAcIoY2FO6BpjA2LPoqzh6FIKx4Bl9xuqnpoQP/+KbwrNXBDszmaMZlARkrt4toZI1phVHbNemBNfo/+3qGsGZEW[/tex]
举一反三
- 求图3-19所示信号的频谱函数。[br][/br][img=317x262]17a3349ef6be932.png[/img]
- 求图3-21所示信号的频谱函数。[br][/br][img=253x200]17a335804bc7223.png[/img]
- 求图3-32所示周期性冲激信号的频谱函数。[br][/br][img=329x248]17a33c48eb791d9.png[/img]
- 利用三种方法求题4.20图所示信号的频谱。[br][/br][img=270x184]17a476a49cd15dc.png[/img]
- 图 10-12( a )所示系统,其中 [tex=1.714x1.357]AphGGQbUXHAeuIs1fgWQNA==[/tex] 的频谱如图 10-12( b )所示,[tex=3.0x1.357]sewg5QwPKOn7w7wgfdPAVuwqkrCzSKPDGly088lsz4g=[/tex]的频谱如图 10-12( c )所示。[br][/br][img=681x428]17a464f8d7042bc.png[/img][br][/br]求信号 [tex=1.714x1.357]AphGGQbUXHAeuIs1fgWQNA==[/tex]
内容
- 0
求图5-7所示信号的拉普拉斯变换。[br][/br][img=369x221]17a3448107ecc2f.png[/img]
- 1
求图5-32所示各信号的拉普拉斯变换。[img=752x311]17a37bfad3d094f.png[/img][br][/br]
- 2
[img=239x211]17a5b76544ccb31.png[/img]求图所示三角形调幅信号的频谱。
- 3
求图所示三角调幅信号的频谱。[img=366x367]17a4c95f0f8d94e.png[/img]
- 4
试用时域微积分性质,求图所示信号的频谱。[img=208x145]17aed91a18c6881.png[/img]