設計FIR濾波器作業報告學號：姓名：設計FIR濾波器作業報告本設計主要內容是利用MATLAB驗證設計思路并用CCS3.3仿真環境設計一個FIR濾波器，要求濾除給定的疊加正弦波的兩個較高頻分量。給定波形函數為：y=sin(2*pi*100*t)+sin(2*pi*250*t)+sin(2*pi*270*t)。設計思路：輸入信號是頻率為100Hz、250HZ、270Hz的合成正弦等幅信號，由于給定的諧波分量最高為270Hz，根據奈奎斯特準則，采樣頻率應大于最高頻率分量的2倍，即大于2*270，故可以以600Hz的采樣頻率進行采樣，即fs=600Hz。設計了一個截止頻率為200Hz的低通濾波器，目的是通過所設計的低通bartlett濾波器將信號源中頻率為200Hz以上的信號濾掉，留下頻率為100Hz的信號，達到濾波的效果。利用MATLAB設計合適的濾波器實現濾波，然后得到其濾波器系數在CCS的simulator方式下編寫濾波程序，調用波形數據，實現濾波，并觀看濾波前后的信號波形圖、頻譜圖，觀察濾波達到預期效果。設計過程在MATLAB中進行算法驗證MATLAB語言由于具有數值計算功能、符號計算功能、數據可視化功能、建模仿真可視化功能，使得MATLAB在命題構思、模型建立、仿真研究、假想驗證、數據源可視化各環節起著強大的作用。因此在設計中必須先在MATLAB語言中設計一個FIR濾波器。本設計采用的是bartlett窗函數。下面是在MATLAB中設計的27階FIR型bartlett濾波器程序：clearall; %請寄存器clf; %清屏N=256; %清數據點fs=600; %采樣頻率dt=1/fs; %采樣時間間隔fort=1:Nf1=250;f2=100;f3=270;y(t)=(sin(2*pi*f1*t*dt)+sin(2*pi*f2*t*dt)+sin(2*pi*f3*t*dt));%產生合成信號x(t)=round(10000*y(t)); %為DSP匯編程序做數據轉換endfigure(1)plot(y),title('濾波前的波形圖像');fp=200fst=250NL=26f1=200;w1=2*pi*f1/fswindow=bartlett(NL+1) %窗函數n=1:NL+1hd=sin(w1*(n-NL/2))./(pi*(n-NL/2));hd(NL/2)=0.67;h=hd.*rot90(window)h1=h*32768;h2=fft(h,N); %將信號做FFT變換pyy=h2.*conj(h2); %做功率譜分析f=(0:(N/2-1));fori=1:N/2-1f(i)=f(i)*fs/N;endfigure(2)plot(f,pyy(1:N/2)),title('濾波器的頻譜圖像');yy1=filter(h,1,y); %濾波figure(3)plot(yy1),title('濾波后的波形圖像');y=fft(y,N);pyy=y.*conj(y);f=(0:(N/2-1));fori=1:N/2-1f(i)=f(i)*fs/N;endfigure(4)subplot(1,2,1),plot(f,pyy(1:N/2)),title('濾波前的波形頻譜圖像');y=fft(yy1,N);pyy=y.*conj(y);f=(0:(N/2-1));fori=1:N/2-1f(i)=f(i)*fs/N;endsubplot(1,2,2),plot(f,pyy(1:N/2)),title('濾波后的波形頻譜圖像')其中采樣點為256個，采樣頻率為600Hz，輸入信號為100Hz、250Hz、270Hz的合成信號，設定的截止頻率為200Hz，通過FIR濾波器后，期望保留的信號是100Hz的信號，200Hz以上的頻率基本被濾掉。圖1是濾波前的圖形，圖2是濾波后的圖形，圖3為濾波器頻譜圖像，圖4濾波前后的波形頻譜圖像。從這四個圖中可以看住原始信號中的頻率有100Hz、250Hz、270Hz，經過濾波后200Hz以上的信號成分基本上被濾掉。只留下100Hz的信號。圖1濾波前波形圖像圖2濾波后波形圖像圖3濾波器的頻譜圖像圖4.濾波前后的波形頻譜圖像在CCS環境的仿真首先配置處理器項，進入CCStudiov3.3中，編寫程序，程序如下： .mmregs.reffilter_start.def_c_int00K_DATA_SIZE.set256K_BUFFER_SIZE.set32K_STACK_SIZE.set256K_B.set27K_CIR.setK_BUFFER_SIZESTACK.usect"stack",K_STACK_SIZESYSTEM_STACK.setK_STACK_SIZE+STACKDATA_DP.usect"filter_vars",0filterdata.usect"filter_vars",K_DATA_SIZEbufferdatay.usect"filter_vars",K_BUFFER_SIZE*2bufferdatax.usect"filter_vars",K_BUFFER_SIZE*2.data.globalinputdatainputdata.WORD16750,-5878,18090,-26831,6340,-9511,11750,11443.WORD-6910,0,-16750,5878,5570,9511,0,-7810.WORD-11750,5878,570,17321,-6910,-5878,-5570,-9511.WORD23660,-9511,18090,-23198,-570,0,570,23198,-18090.WORD9511,-23660,9511,5570,5878,6910,-17321,-570.WORD-5878,11750,7810,0,-9511,-5570,-5878,16750.WORD0,6910,-11443,-11750,9511,-6340,26831,-18090.WORD5878,-16750,0,16750,-5878,18090,-26831,6340.WORD-9511,11750,11443,-6910,0,-16750,5878,5570.WORD9511,0,-7810,-11750,5878,570,17321,-6910.WORD-5878,-5570,-9511,23660,-9511,18090,-23198,-570.WORD0,570,23198,-18090,9511,-23660,9511,5570.WORD5878,6910,-17321,-570,-5878,11750,7810,0.WORD-9511,-5570,-5878,16750,0,6910,-11443,-11750.WORD9511,-6340,26831,-18090,5878,-16750,0,16750.WORD-5878,18090,-26831,6340,-9511,11750,11443,-6910.WORD0,-16750,5878,5570,9511,0,-7810,-11750.WORD5878,570,17321,-6910,-5878,-5570,-9511,23660.WORD-9511,18090,-23198,-570,0,570,23198,-18090.WORD9511,-23660,9511,5570,5878,6910,-17321,-570.WORD-5878,11750,7810,0,-9511,-5570,-5878,16750.WORD0,6910,-11443,-11750,9511,-6340,26831,-18090.WORD5878,-16750,0,16750,-5878,18090,-26831,6340.WORD-9511,11750,11443,-6910,0,-16750,5878,5570.WORD9511,0,-7810,-11750,5878,570,17321,-6910.WORD-5878,-5570,-9511,23660,-9511,18090,-23198,-570.WORD0,570,23198,-18090,9511,-23660,9511,5570.WORD5878,6910,-17321,-570,-5878,11750,7810,0.WORD-9511,-5570,-5878,16750,0,6910,-11443,-11750.WORD9511,-6340,26831,-18090,5878,-16750,0,16750.WORD-5878,18090,-26831,6340,-9511,11750,11443,-6910.WORD0,-16750,5878,5570,9511,0,-7810.text_c_int00:.asgAR2,ORIGIN.asgAR3,INPUT.asgAR4,FILTER.asgAR5,OUTPUTSTART:SSBXFRCTSSBXINTMLD#DATA_DP,DPSTM#STACK,SPCALLfilter_startNOPNOPNOPLOOPBLOOP.defh0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11,h12,h13,h14,h15,h16,h17,h18,h19,h20,h21,h22,h23,h24,h25,h26.deffilter_starth0 .set0000Hh1 .set-003FHh2 .set008AHh3 .set0000Hh4 .set-015BHh5 .set01F0Hh6 .set0000Hh7 .set-03CDHh8 .set056EHh9 .set0000Hh10 .set-0D92Hh11 .set1DDBHh12 .set4F2AHh13 .set2349Hh14 .set-1049Hh15 .set0000Hh16 .set06C9Hh17 .set-04E3Hh18 .set0000Hh19 .set02B7Hh20 .set-0209Hh21 .set0000Hh22 .set0116Hh23 .set-00BEHh24 .set0000Hh25 .set0035Hh26 .set0000H.textfilter_start:STM#K_CIR,BKSTM#1,AR0 ；設置循環緩沖區的大小和步長STM#inputdata,ORIGINSTM#bufferdatax,INPUT;STM#bufferdatay,FILTERSTM#filterdata,OUTPUT STM#K_DATA_SIZE-1,BRC ；設置快循環計數器RPTBfilter_end-1MVDD*ORIGIN+,*INPUTRPT#K_B-1-1MAR*INPUT-0%MPY *INPUT+0%,#h26,B LD B,A MPY *INPUT+0%,#h25,B ADD B,A MPY *INPUT+0%,#h24,B ADD B,A MPY *INPUT+0%,#h23,B ADD B,A MPY *INPUT+0%,#h22,B ADD B,A MPY *INPUT+0%,#h21,B ADD B,A MPY *INPUT+0%,#h20,B ADD B,A MPY *INPUT+0%,#h19,B ADD B,A MPY *INPUT+0%,#h18,B ADD B,A MPY *INPUT+0%,#h17,B ADD B,A MPY *INPUT+0%,#h16,B ADD B,A MPY *INPUT+0%,#h15,B ADD B,A MPY *INPUT+0%,#h14,B ADD B,A MPY *INPUT+0%,#h13,B ADD B,A MPY *INPUT+0%,#h12,B ADD B,A MPY *INPUT+0%,#h11,B ADD B,A MPY *INPUT+0%,#h10,B ADD B,A MPY *INPUT+0%,#h9,B ADD B,A MPY *INPUT+0%,#h8,B ADD B,A MPY *