./2ASK、2FSK、2PSK數字調制系統的Matlab實現及性能分析比較指導教師:班級： 學號： ：引言：數字信號有兩種傳輸方式,分別是基帶傳輸方式和調制傳輸方式,即帶通,在實際應用中,因基帶信號含有大量低頻分量不利于傳送,所以必須經過載波和調制形成帶通信號,通過數字基帶信號對載波某些參量進行控制,使之隨機帶信號的變化而變化,這這一過程即為數字調制。數字調制為信號長距離高效傳輸提供保障,現已廣泛應用于生活和生產中。另外根據控制載波參量方式的不同,數字調制主要有調幅〔ASK,調頻<FSK>,調相<PSK>三種基本形式。本次課題針對于二進制的2ASK、2FSK、2PSK進行討論,應用Matlab矩陣實驗室進行仿真,分析和修改,通過仿真系統生成一個人機交互界面,以利于仿真系統的操作。通過對系統的仿真,更加直觀的了解數字調制系統的性能及影響其性能的各種因素,以便于比較,評論和改進。關鍵詞：數字,載波,調制,2ASK,2FSK,2PSK,Matlab,仿真,性能,比較,分析正文：一.數字調制與解調原理1.12ASK〔12ASK2ASK就是把頻率、相位作為常量,而把振幅作為變量,信息比特是通過載波的幅度來傳遞的。由于調制信號只有0或1兩個電平,相乘的結果相當于將載頻或者關斷,或者接通,它的實際意義是當調制的數字信號"1時,傳輸載波；當調制的數字信號為"0"時,不傳輸載波。表達式為：1.22FSK2FSK可以看做是2個不同頻率的2ASK的疊加,其調制與解調方法與2ASK差不多,主要頻率F1和F2,不同的組合產生所要求的2FSK調制信號。公式如下：1.32PSK2PSK以載波的相位變化為基準,載波的相位隨數字基帶序列信號的1或者0而改變,通常用已經調制完的載波的0或者π表示數據1或者0,每種相位與之一一對應。二．數字調制技術的仿真實現本課程設計需要借助MATLAB的M文件編程功能,對2ASK.2PSK.2FSK進行調制與解調的設計,并繪制出調制與解調后的波形,誤碼率的情況分析,軟件仿真可在已有平臺上實現。1.2ASK代碼主函數closeallclearalln=16;fc=1000000;bitRate=1000000;N=50;%noise=ti;noise=10;signal=source<n,N>;%生成二進制代碼transmittedSignal=askModu<signal,bitRate,fc,N>;%調制后信號signal1=gussian<transmittedSignal,noise>;%加噪聲configueSignal=demoASK<signal1,bitRate,fc,n,N>;source代碼functionsendSignal=source<n,N>sendSignal=randint<1,n>bit=[];fori=1:length<sendSignal>ifsendSignal<i>==0bit1=zeros<1,N>;elsebit1=ones<1,N>;endbit=[bit,bit1];endfigure<1>plot<1:length<bit>,bit>,title<'transmittingofbinary'>,gridon;axis<[0,N*length<sendSignal>,-2,2]>;endaskModu代碼functiontransmittedSignal=askModu<signal,bitRate,fc,N>%signal為輸入信號,bitrate為bit速率,fc調制信號頻率,N%signal=[00101101];%bitRate=1000000;%fc=1000000;%N=32;t=linspace<0,1/bitRate,N>;c=sin<2*pi*t*fc>;transmittedSignal=[];fori=1:length<signal>transmittedSignal=[transmittedSignal,signal<i>*c];endfigure<2>%畫調制圖plot<1:length<transmittedSignal>,transmittedSignal>;title<'ModulationofASK'>;gridon;figure<3>%畫頻譜實部m=0:length<transmittedSignal>-1;F=fft<transmittedSignal>;plot<m,abs<real<F>>>,title<'ASK_frequency-domainanalysisreal'>;gridon;%figure<4>畫頻譜虛部%plot<m,imag<F>>;title<'ASK_frequency-domainanalysisimag'>;%gridon;endCheckRatePe代碼functionPeWrong=CheckRatePe<signal1,signal2,s>rights=0;wrongs=0;forki=1:s-2if<signal1<ki>==signal2<ki>>rights=rights+1;elsewrongs=wrongs+1;endendPeWrong=wrongs/<wrongs+rights>;enddemoASK代碼functionbitstream=demoASK<receivedSignal,bitRate,fc,n,N>loadnumsignal1=receivedSignal;signal2=abs<signal1>;%??á÷signal3=filter<num1,1,signal2>;%LPF,°ü???ì2¨IN=fix<length<num1>/2>;%?ó3ùê±??bitstream=[];LL=fc/bitRate*N;i=IN+LL/2;while<i<=length<signal3>>%?D??bitstream=[bitstream,signal3<i>>=0.5];i=i+LL;endfigure<6>subplot<3,1,1>;%接收波形plot<1:length<signal1>,signal1>;title<'Waveofreceivingterminal<includingnoise>'>;gridon;subplot<3,1,2>;%接收整流后波形plot<1:length<signal2>,signal2>;title<'Waveofcommutate'>;gridon;subplot<3,1,3>;%包絡檢波波形plot<1:length<signal3>,signal3>;title<'WaveofLPF'>;gridon;bit=[];fori=1:length<bitstream>ifbitstream<i>==0bit1=zeros<1,N>;elsebit1=ones<1,N>;endbit=[bit,bit1];endfigure<7>%解調后的二進制波形plot<bit>,title<'binaryofreceivingterminal'>,gridon;axis<[0,N*length<bitstream>,-2.5,2.5]>;endgussian代碼%加高斯白噪聲functionsignal=gussian<transmittedSignal,noise>signal=sqrt<2>*transmittedSignal;signal=awgn<signal,noise>;figure<5>plot<1:length<signal>,signal>;title<'Waveincludingnoise'>,gridon;endfsk主函數代碼closeallclearalln=16;%二進制代碼長度f1=18000000;%頻率1f2=6000000;%頻率2bitRate=1000000;%bit速率N=50;%碼元寬度%noise=ti;noise=10;%家性噪聲大小signal=source<n,N>;%產生二進制代碼transmittedSignal=fskModu<signal,bitRate,f1,f2,N>;%調制signal1=gussian<transmittedSignal,noise>;%加噪聲configueSignal=demoFSK<signal1,bitRate,f1,f2,N>;%解調source代碼%二進制信號產生函數functionsendSignal=source<n,N>sendSignal=randint<1,n>bit=[];fori=1:length<sendSignal>ifsendSignal<i>==0bit1=zeros<1,N>;elsebit1=ones<1,N>;endbit=[bit,bit1];endfigure<1>plot<bit>,title<'transmittingofbinary'>,gridon;axis<[0,N*length<sendSignal>,-2.5,2.5]>;endfskModu代碼%頻率調制函數functiontransmittedSignal=fskModu<signal,bitRate,f1,f2,N>t=linspace<0,1/bitRate,N>;c1=sin<2*pi*t*f1>;%調制信號1c2=sin<2*pi*t*f2>;%調制信號2transmittedSignal=[];fori=1:length<signal>%調制ifsignal<i>==1transmittedSignal=[transmittedSignal,c1];elsetransmittedSignal=[transmittedSignal,c2];endendfigure<2>%畫調制后波形圖plot<1:length<transmittedSignal>,transmittedSignal>;title<'ModulationofFSK'>;gridon;figure<3>%畫調制后頻譜圖m=0:length<transmittedSignal>-1;F=fft<transmittedSignal>;plot<m,abs<real<F>>>,title<'ASK_frequency-domainanalysisreal'>;gridon;enddemoFSK代碼functionbitstream=demoFSK<receivedSignal,bitRate,f1,f2,N>loadnumsignal1=receivedSignal;signal2=filter<gaotong,1,signal1>;%通過HPF,得到高通分量signal3=abs<signal2>;%整流signal3=filter<lowpass,1,signal3>;%通過低通,形成包絡bitstream=[];IN1=fix<length<lowpass>/2>+fix<length<gaotong>/2>;%延遲時間bitstream1=[];LL=N;%每個bit的抽樣點數i=IN1+LL/2;while<i<=length<signal3>>%判決bitstream1=[bitstream1,signal3<i>>=0.5];i=i+LL;endbitstream1figure<5>subplot<3,1,1>;plot<1:length<signal1>,signal1>;title<'Waveofreceivingterminal<includingnoise>'>;gridon;subplot<3,1,2>;plot<1:length<signal2>,signal2>;title<'AfterPassingHPF'>;gridon;subplot<3,1,3>;plot<1:length<signal3>,signal3>;title<'AfterPassingLPF'>;gridon;signal4=filter<daitong,1,signal1>;%通過BPF得到低頻分量signal5=abs<signal4>;%整流signal5=filter<lowpass,1,signal5>;%通過LPF,形成包絡IN2=fix<length<lowpass>/2>+fix<length<daitong>/2>;%延遲時間bitstream2=[];LL=N;%每個bit的的抽樣點數i=IN2+LL/2;while<i<=length<signal5>>%判決bitstream2=[bitstream2,signal5<i>>=0.5];i=i+LL;endbitstream2figure<6>subplot<3,1,1>;plot<1:length<signal1>,signal1>;title<'Waveofreceivingterminal<includingnoise>'>;gridon;subplot<3,1,2>;plot<1:length<signal4>,signal4>;title<'AfterPassingBPF'>;gridon;subplot<3,1,3>;plot<1:length<signal5>,signal5>;title<'AfterPassingLPF'>;gridon;fori=1:min<length<bitstream1>,length<bitstream2>>%判決if<bitstream1<i>>bitstream2<i>>bitstream<i>=1;elsebitstream<i>=0;endendbitstreambit=[];%接收端波形fori=1:length<bitstream>ifbitstream<i>==0bit1=zeros<1,N>;elsebit1=ones<1,N>;endbit=[bit,bit1];endfigure<7>plot<bit>,title<'binaryofreceivingterminal'>,gridon;axis<[0,N*length<bitstream>,-2.5,2.5]>;endCheckRatePe代碼functionPeWrong=CheckRatePe<signal1,signal2,s>rights=0;wrongs=0;forki=1:s-2if<signal1<ki>==signal2<ki>>rights=rights+1;elsewrongs=wrongs+1;endendPeWrong=wrongs/<wrongs+rights>;endgussian代碼functionsignal=gussian<transmittedSignal,noise>signal=sqrt<2>*transmittedSignal;signal=awgn<signal,noise>;figure<4>plot<1:length<signal>,signal>,title<'AddingNoise'>;gridon;end2psk主函數代碼closeallclearalln=16;%二進制碼長fc=1000000;%載波頻率bitRate=1000000;信息頻率N=50;%碼寬noise=10;%信道加性噪聲大小signal=source<n,N>;生成二進制代碼transmittedSignal=bpskModu<signal,bitRate,fc,N>;對信號進行調制并進行頻譜分析signal1=gussian<transmittedSignal,noise>%加信道噪聲configueSignal=demoBPSK<signal1,bitRate,fc,n,N>;%信號解調source代碼functionsendSignal=source<n,N>sendSignal=randint<1,n>bit=[];fori=1:length<sendSignal>ifsendSignal<i>==0bit1=zeros<1,N>;elsebit1=ones<1,N>;endbit=[bit,bit1];endfigure<1>plot<bit>,title<'transmittingofbinary'>,gridon;axis<[0,N*length<sendSignal>,-2.5,2.5]>;endbpskModu代碼functiontransmittedSignal=bpskModu<signal,bitRate,fc,N>t=linspace<0,1/bitRate,N>;c1=sin<2*pi*t*fc>;c2=sin<2*pi*t*fc+pi>;transmittedSignal=[];fori=1:length<signal>ifsignal<i>==1transmittedSignal=[transmittedSignal,c1];elsetransmittedSignal=[transmittedSignal,c2];endendfigure<2>%畫調制圖plot<1:length<transmittedSignal>,transmittedSignal>;title<'ModulationofBPSK'>;gridon;figure<3>%畫頻譜圖m=0:length<transmittedSignal>-1;F=fft<transmittedSignal>;plot<m,abs<real<F>>>,title<'BPSK_frequency-domainanalysisreal'>;gridon;endCheckRatePe代碼functionPeWrong=CheckRatePe<signal1,signal2,s>rights=0;wrongs=0;forki=1:s-2if<signal1<ki>==signal2<ki>>rights=rights+1;elsewrongs=wrongs+1;endendPeWrong=wrongs/<wrongs+rights>;enddemoBPSK代碼functionbitstream=demoBPSK<receivedSignal,bitRate,fc,n,N>loadnum%讀取num存儲的低通濾波用的數據signal1=receivedSignal;t=linspace<0,1/bitRate,N>;c=sin<2*pi*t*fc>;signal=[];fori=1:nsignal=[signal,c];endsignal2=signal1.*signal;%乘同頻同相sinsignal3=filter<num1,1,signal2>;%LPF,包絡檢波3IN=fix<length<num1>/2>;%?延遲時間bitstream=[];LL=fc/bitRate*N;i=IN+LL/2;while<i<=length<signal3>>%判決bitstream=[bitstream,signal3<i>>=0];i=i+LL;endfigure<5>subplot<3,1,1>;%畫接收的包含噪聲的波形plot<1:length<signal1>,signal1>;title<'Waveofreceivingterminal<includingnoise>'>;gridon;subplot<3,1,2>;%相干解調波形plot<1:length<signal2>,signal2>;title<'AfterMultiplingsinFuction'>;gridon;subplot<3,1,3>;%包絡檢波波形plot<1:length<signal3>,signal3>;title<'WaveofLPF'>;gridon;bit=[];fori=1:length<bitstream>ifbitstream<i>==0bit1=zeros<1,N>;elsebit1=ones<1,N>;endbit=[bit,bit1];endfigure<6>二進制接收信號波形plot<bit>;title<'binaryofreceivingterminal'>;gridon;axis<[0,N*length<bitstream>,-2.5,2.5]>;endgussian代碼functionsignal=gussian<transmittedSignal,noise>signal=sqrt<2>*transmittedSignal;signal=awgn<signal,noise>;figure<4>plot<1:length<signal>,signal>,gridon;title<'Addingnoise'>end三種調制方式的性能比較:loadPeRate;loadPeRatep;%補償誤差fpeask<15>=1e-3;fpefsk<9>=1e-3;fpepsk<24>=0.002;fpepsk<26>=1e-3;figure<1>sem