12.3 Discrete-Timc Foiirirr Transform m t l from t h i s TVP 305 can dircctly obtain Figure 12.6 shoivs 011 the lelt the first few vdues of this fqxmcritiwl series for it real (1 and the right shows thc magnitude of the spectrum T h e spedrurri is clearly periodit with period 2n As (12.36) does iiot convc'rgt' for (1 = I , the sprc'trim of the [uri fimrtioii (12.33) is iiot contaiiied in (12.36) ab a spc ansform Qf a Rectangle Series ~ + w:mt ~ o to find the F* t,rwnsform x ( P of ) a rrctanglc scries wit11 length N ( 123 ) as showir in Figure 12.7 Inserting this inlo tlir tic4ining cquatiorl (12 13) Icads to N-1 Figixrct 12 7: Rectangle serirs of length N a liriitc geometr ic wriw (12.38)