基于DSP的數(shù)字濾波器的設(shè)計(jì)與仿真

MATLABCCS設(shè)定模擬信號(hào)的采樣頻率為48000Hz，。設(shè)計(jì)一種FIR低通濾波器，其參數(shù)為： FIR低通濾波器采樣頻率 阻帶截止頻率：16000Hz通帶最大衰減 阻帶最少衰減 濾波器系數(shù) 由MATLAB根據(jù)前述參數(shù)求得計(jì)／分析工具FDATOOL設(shè)計(jì)FIR濾波器圖1HzhnznN1

ynhkxnxnkhkN是濾波器的階數(shù)Yn表ynxn、hn

ynxnhnFDATOOL,根據(jù)濾波規(guī)定設(shè)立濾波器類型、通帶截止頻率、指定DesignFilter，生成濾波器系數(shù)。把生成的濾波器系數(shù)傳到目的DSP。選擇菜單Targets->ExporttoCodeComposerStudio(tm)IDEExporttoCHeaderFileCheaderfile32b，16bOK，保存該頭文獻(xiàn)，需指定文獻(xiàn)名(filtercoeff．h)c：\ti\myprojects\fir工程中)。coeff.word,在每行的前面加上.word，比且把每行的最后的逗號(hào)去掉。4在本實(shí)驗(yàn)中使用MATLABMATLABDSPDSP中實(shí)現(xiàn)帶通CCSDSP的濾波效果。MATLAB4.1生成fir圖4.1MATLABCCS4.2是是是否有待濾波數(shù)據(jù)圖4.2CCS5MATLABDSPFIRDSP中編寫解決程序，MATLABFDATOOL能快速設(shè)計(jì)一種FIR,然后把濾波器系數(shù)以頭文獻(xiàn)形式導(dǎo)入CCS中,頭文獻(xiàn)中MATLAB輔助DSP實(shí)現(xiàn)FIR數(shù)字濾波器含濾波器階數(shù)和系數(shù)數(shù)組,在MATLABDSP程序并顯示、分析解決后的數(shù)據(jù)。使用該辦法,便MATLAB中設(shè)計(jì)的濾波器系數(shù)變MATLAB中先編寫程序，查看待濾波和已濾波的信號(hào)的時(shí)域和頻域5.15.2所示。圖5.1待濾波信號(hào)的時(shí)域 圖5.2待濾波信號(hào)的頻域FDATOOLFIR5.3圖 FIR濾波器的參ExportNumeratorB5.45.4Export5.55.6圖5.5已濾波信號(hào)時(shí)域波形 圖5.6已濾波信號(hào)頻域波形16bitOKfir.hC語言頭文獻(xiàn)。將系5.7MATLAB在CCS中編寫匯編語言程序，進(jìn)行調(diào)試，實(shí)現(xiàn)帶通濾波的功效。在CCSIDELHM.pjtfir.asm。另外根據(jù)fir.cmdMATLAB生成的LHM.hinput1.datLHM.pjt工程文獻(xiàn)夾下，進(jìn)行編譯、鏈接,生成LHM.out。data5.85.8dataMATLAB程序設(shè)計(jì)中，采樣頻率設(shè)立的過小，截止頻率不小于采樣FIR.mCCS在.hcoefffir.hinput.dat(7)在View的GraphTime/frequencygraphpropertydialog框，未修改抽樣點(diǎn)數(shù)。顯示的圖形出現(xiàn)差別CCSViewGraphTime/frequencygraphpropertydialog框。5.9所示，輸出濾波前5.9GraphpropertydialogOK5.105.105.115.115.125.135.125.13由上述的全部截圖可知，輸入?yún)?shù)中，通帶截止頻率和阻帶截止頻率是比較重要的兩個(gè)參數(shù)，不適宜過小，過小濾掉的高頻成分太多，很難還原出遠(yuǎn)波形的形狀，也不適宜過大，過大濾波效果欠佳。在本課程4000Hz4500H顯示圖形時(shí)的，時(shí)域顯示的抽樣點(diǎn)數(shù)為1024，頻域顯示的帶寬為0.5Hz5.105.125.11和5.13能夠懂得，濾波前的時(shí)域信號(hào)的波形圖的波形很雜亂，很難看出信FIR COEF： - - start: PORTRPA1,@x+1 PORTW*AR2+,PA0 PORTRFIR.title .usect .usect table: start: #- PORTRPA1,@xn MAC*AR2+0%,*AR3+0%,A PORTW@y,PA0 PORTRlhm.h-85,-64,-61,-36,8,62,110,136,96,42,-11,-44,-44,-11,39,85,88,37,-29,-83,-101,-73,-7,70,131,82,-5,-96,-151,-144,-72,37,191,162,61,-76,-191,-231,-174,-35,256,278,180,-7,-208,-337,-330,-176,316,445,392,156,-178,-475,-599,-470,-361,745,857,594,-6,-748,-1336,-1456,-386,2192,4154,5816,6768,6768,5816,4154,386,-893,-1456,-1336,-748,-6,594,857,361,-108,-470,-599,-475,-178,156,392,316,72,-176,-330,-337,-208,-7,180,256,132,-35,-174,-231,-191,-76,61,191,140,37,-72,-144,-151,-96,-5,131,124,70,-7,-73,-101,-83,-29,88,106,85,39,-11,-44,-44,-11,96,131,136,110,62,8,-36,-61,--Fir.asm .global_c_int00 .set154 .set ;TheLengthofInput.usect(ORDER-.usect(ORDER- output output AR0, AR2, AR3, AR5, AR6,;Copy #ORDER- #1,FIR_INDEX #xn,FIR_DATA ;Copyxn(data)toRPTZA,#ORDER- A, #(xn+ORDER-1),FIR_DATA #(a0+ORDER-1),FIR_COEFSTM#input,DATA_IN ;Getdatafrom"input"STM#output,DATA_OUT ;Writedatato"output"STM#D_LEN-1,BRCRPTBDnext-STM#ORDER,*D