数字信号处理第一章 离散时间信号和系统ppt课件

1、12,1( )0,1nnx nn 2 ,0( )1,0nny nnn12 ,13( )( ) ,1221,0nnnx ny nnnn 12 ,13( )( ) ,1221,0nnnx ny nnnn 12,1( )0,1nnx nn 2 ,0( )1,0nny nnn10,11( )( ),12(1)2,0nnx ny nnnn 10,11( )( ),12(1)2,0nnx ny nnnn x(n)12,1( )0,1nnx nn 22,11(1)0,11nnx nn x(n)22,11(1)0,11nnx nn 12,1( )0,1nnx nn 12,14 ( )0,1nnx nn 12,

2、1( )0,1nnx nn 12,1()0,1nnxnn 设序列为设序列为x(n)，那么序列，那么序列 (1.7) 定义为对定义为对x(n)的累加，表示将的累加，表示将n 以前的一以前的一切切x(n)值求和。值求和。nkkxny)()()() 1(2)2()() 1()()(2nxnxnxnxnxnxnx)2() 1(2)() 1()()()(2nxnxnxnxnxnxnx(按二项式定理展开按二项式定理展开)( / ),0,1,2,( )0,x n m n ml lz nn其 它 2| ( )|nEx n( )( )( )() ()my nx nz nx m z nm1001()( )()1n

3、nnnmnmmmmaynxmzn maa aa 1001()()( )1nnnnm nmmmmaynxm znm a a aa aaaaaanynnmmmnmn1)(144040aaaaaanynnmmmnmn 1) (144040410660( )nnmkmnky naa47101066001nnnkkkkaaaaaa0, 00, 1)(nnnmnmnmn0, 1)(1,0( )0,0nu nn1,()0,nmu nmnm(n) = u(n)-u(n-1) 0( )()( )nkku nnkk1,01( )0,NnNR n 其 它NmNmnnR0)()( )( )()NRnu nu nN(

4、)( )nx na u nx(n)= Asin(n+) n用极坐标表示用极坐标表示 ( )e(cosjsin)ecosejsinnnnx nnnnnjarg ( )j( )( ) eeex nnnx nx n( )x nkN2( )5sin(3)4x nn3( )2cos(7)4x nn3( )2cos(7)4x nn( )() ()mx nx mnmmnmnnxmnmx, 0),(=)( )(nm 为恣意常整数为恣意常整数 ( )() ( -)mx nx mn m ( ) ( )() ( -)my nT x nTx mn m( )() ( -)my nx m Tn m( )() ( -)(

5、)( )my nx m h n mx nh n( )( ) ( - )( ) ( - )nmmy nx m h n mx m h n m000()( ) ( - )nmy nx m h n m1( )() ( -)() ( -)() ( -)mnmmny nx m h n mx m h n mx m h n m |( ) |nh n +|( ) | |() () |() |() |M|() |mmmy nh m x nmh mx nmh m |( ) |nh n 1,()0( )1,()0hnx nhn(0)( ) ()| ()| ( )|mmmyx m h nmhmh m ( )()my n

6、x m1,0( )()0,0mnny nu mn1| | 111, |1|( ) |,|1annnnnah naaa31( )(1)(2)3022y ny ny n00()()(1.44)NMkrkra y nkb x nr0010( )()()(1.45)krNMabaakry ny nkx nr ( )( )nh na u nh(n)= ah(n-1)+ (n) ( )( )( )( )()( ) ()(1.53)() ()(1.54)aaaannanxtxtp txttnTxttnTxnTtnT( )()(1.52)np ttnT1(j)(j)(j)2aaXXpj( )esrtrrp t

7、c222222jjj011( )ed()ed111( )edeTTssTTTsTrtrtrnrtcp tttnTtTTttTTTj1( )esrtrp tTW+ = - =j12(j)Fe(jj)(1.55)srtsrrprTTWpWd WW+ + = - = - =-邋1(j)F( )( )(j)(j)21(j)(jj)1(jj)(1.57)aaaasrasrXx tp tXpXrTXrTn取样信号的频谱是延取样信号的频谱是延续时间信号频谱以取续时间信号频谱以取样频率为周期进展周样频率为周期进展周期延拓而成期延拓而成n频谱幅度是原信号频频谱幅度是原信号频谱幅度的谱幅度的1/T1/T倍倍2scn利用理想低通滤波器复原满足奈奎斯特取样定利用理想低通滤波器复原满足奈奎斯特取样定理的取样信号。理的取样信号。1212,|(j)0,|sasTH(j)F( )(j)(j)(j)aaaaYy tXHXn单位脉冲呼应单位脉冲呼应h(t) ( )( )aax tx t22jj221( )(j)ed(j)ed2sinsin(/ )(1.59)(/ )sssstth tHHtt Tt Tt( )( )* ( )( ) ()d()