案例2sjtu-dsp课件老师群

1、6structuresfordiscrete- time system6.1 signal flow graph ion of 6structuresfordiscrete- time system6.1 signal flow graph ion of coefficient differencebasic structures for IIR directcascade parallelbasicstructuresforFIRdirectcascade structuresforlinear-phaseFIR6.1signal6.1signalflowgraph（信号流图ion of l

2、ineardifference equationsWhen a linear time-invariant discrete-time system is implemented with discrete-timeog or digital hardware, the difference equation or the system function represenionmustbeconvertedtogorithm or structuret can be realizedhedesired The basic elements required for implemenion of

3、 a linear time- invariant discrete-time system are adders, multiprs,andmemory for storing delayed sequence values.erconnectionofthesebasicelementsisconvenientlybysignalflowFormally,aFormally,asignalflowgraphisanetworkofdirectedbranches t connecnodes（节点）. Assoted with each node is avariableornodevalu

4、e.Weoftenindicatethevalueofnodektheionwkn.Branch(j,k)（支路）denotesaoriginatingatnodejandterminatingatnodek,withthefrom j to k being indicated by an arrowhead on the branch. If the outputofthebranch isaconstantmultipleordelayoftheinputto the branch, the constant or z-1 is shown next to the arrowhead.Fi

5、gureFigure节点：Figure节点：源、阱、网支路：常数、z-1、1、-节点值=所有输入支路之( z X WW)zz(2)2Y(z1z( z () )z( z X WW)zz(2)2Y(z1z( z () )z254W(zY ()H ( z z ()2zX zzW Y)zW)z36edforms转置edforms转置形式）Flowgraphreversalitioncantransformaflowoanotherformwhile n input and outputleavingtheoverallsystemfunctionbet 转置：所有支路反输入输出交保持输入输出关系不ba

6、sic structures for IIR directdirectMbk zk1basic structures for IIR directdirectMbk zk1 ak zM bk zk H1(z)H2(z)H zNN1 ak zkkkW (z) X (z)H1(z),Y(z) W (z)H2(zNMyn akyn k bk xn kkkMNwn bk xn k, yn wn ak yn kkkMNwn MNwn bk xn k, yn wn ak yn kkkFigure优点：简单；缺点：延迟多；对字长敏感；调整零极点不2k3k 2k3k yn n kCkdouble x3,y2;

7、 p2.directII（典范型Mz bkH zk H2.directII（典范型Mz bkH zk H1(z)H 2 (z) H 2 (z)H1(zN1 az k M: H 2 z ,H1zz bkN1 ak X (z)H 2(zz k W (z) Y (z) W (z)H1(zN wn xn kak wk Mk yn bk wn kNMk k wn NMk k wn xn akwn k，yn bk wn k aN-bM-MzkHMzkHzkN1kzkFigure优点：延迟少一 8 z(1zH1212 8 z(1zH12121z zDirectIIsignalflow0 1008（习题1 z

8、aH1n1（习题1 zaH1n1ya) y a6.2.2cascadeMk1 /20 1 ,Hk6.2.2cascadeMk1 /20 1 ,Hk,2 zH z k N1kkk0k2bkbzItiseasytotavarietyoftheoreticallyequivalentsystemscanobtained by simply paring the poles and zeros in different ways and byorderingthesecond-ordersectionsindifferentways.Theirbehaviowithfinite-arithmeticc

9、anbequiteFigure优Figure优点：对系数量化的灵敏度比直接型低可寻找因有限字长效应造成的误差最小的实数零点极点配对和级联顺序；缺点：不如并行6.2.3parallelMbkzkNNM6.2.3parallelMbkzkNNMz2kHzCk zk 211k 2k1akzkk优点：对系数量化的灵敏度比直接型低硬件实现缺点：不能调整零点，不能用于对零点位置精度要求高的滤波器，例如点阻和窄带带阻。z-z-z-z-Figurez-z-z-z-Figure3 6 z 1 0 z.2z 0 1z 1 0 z.3 6 z 1 0 z.2z 0 1z 1 0 z.2直接II 33z-z- 0.2

10、 zH z 3 0 .5 0.4 17H z 0.2 zH z 3 0 .5 0.4 17H z 1 1 0 .5 0 .4 37-(b)级联z-z-6.2.4.补充格型网-z-z-z-1H6.2.4.补充格型网-z-z-z-1H5zz83优点：对有限字长不敏basicstructuresforFIR directMbasicstructuresforFIR directMMk k H zhkxn k, y(n) Figure又称横向结3 kx y3 kx y k k Cp6.3.2cascadeMMM22Hz6.3.2cascadeMMM22Hzhkzk k0kk111bFigure优点：易

11、于调整零点可用一个二阶环时分复6.3.3structuresforlinear-phaseFIRMyn6.3.3structuresforlinear-phaseFIRMynhkxnkkM /Mkhkxn khkxnkhM/2xnM /2kM /M /M /hkxnkhM/2xnM /2 hM kxnM kkkM /hk(xnkxnM k)hM /2xnM /kM /M /yn hk(xnkxnM k)hM /2xnM /kFigureodd Myn hkxodd Myn hkxnkk0Mk0hkxnkk(M1)/hkxnkhM kxnM khkxnkk0k0hk(xnk xnM kk0(M 1)(M 1)/ynhk(xnk xnM kk0Figure优点：乘法次数减少一6.3.4 补充格型网-z-z-z-(6.3.4 补充格型网-z-z-z-( 11 3H6.4overview6.4overviewoffinite-effects有限字长效应不同实现结构对无限精度实现：结果完全相同只是运算量、速度