uwb.zip_FCC_OFDM QPSK_UWB系统_dpsk_uwb

% ===========LSD对源文件的整理版本=========== % ======缩写 & 简称====== % UWB 超宽带 BPSK 二进制相移键控（模数转换，A→D） % AWGN 加性高斯白噪声 p 默认为pulse % pw 脉冲宽度 doublet 脉冲对（极性未知） % ======阶段1：参数预设 =====阶段1 for fold_stage=1:1 % ======初始化常数====== A=1; % 原文件并没有给出A，推测为AMPLITUDE，或者类似归一化常数，此时设为1 pw1=.2e-9; % 脉冲宽度（纳秒），可根据需要调整 pw=pw1/1.24; % 不准确脉冲宽度的调整系数（1阶约为3-5。第二级约为1-3。） Fs=100e9; % 抽样频率 Fn=Fs/2; % 奈奎斯特频率 t=-1e-9:1/Fs:30e-9; % 以Fs赫兹采样的时间矢量。用于放大/缩小（-1e-9:1/fs:XXXX） % ======公式 & 方程====== jieshu=3; if jieshu==1 y=A*(t/pw).*exp(-(t/pw).^2); % 高斯脉冲的一阶导数=高斯单周期 else y =1*(1 - 4*pi.*((t)/pw).^2).* exp(-2*pi.*((t)/pw).^2); % 高斯二阶导数 end % LSD修改2：将2阶导数改为n阶：diffi_count的起始恒为3 for diffi_count=3:jieshu for i=1:3100 % 微分后长度减一，这里没有调整，可能是隐患 y(i)=Fs*(y(i+1)-y(i)); end end %pulse=doublet(two zero crossings) % 脉冲为脉冲对（过零点两次） % ======噪声设置：调整误码率和信噪比====== % LSD改动1：去除噪声；原函数为源代码中的噪声函数，因实验需要，替代为无噪声 % noise=(1e-50)*(randn(size(t))); % 噪声——加性高斯白噪声（参数为0.2时，信噪比约为7分贝） noise = 0; %对于峰峰值为2伏特的BPSK信号。设置为1e-50以禁用 end % =====阶段2：BPSK 模数转换 =====阶段2 for fold_stage=2:2 % =====一阶导数单循环（百万分之5脉冲） % yp=y+ ... % A*((t-2.5e-9-.2e-9)/pw).*exp(-((t-2.5e-9-.2e-9)/pw).^2)+A*((t-5e-9)/pw).*exp(-((t-5e-9)/pw).^2)+ ... % A*((t-7.5e-9-.2e-9)/pw).*exp(-((t-7.5e-9-.2e-9)/pw).^2)+A*((t-10e-9)/pw).*exp(-((t-10e-9)/pw).^2); % =====二阶导数双峰（5脉冲BPSK） %BPSK调制后脉冲对（YP） yp=1*y+ ... -1*(1-4*pi.*((t-6.41e-9)/pw).^2).*exp(-2*pi.*((t-6.41e-9)/pw).^2)+ ... 1*(1-4*pi.*((t-12.82e-9)/pw).^2).*exp(-2*pi.*((t-12.82e-9)/pw).^2)+ ... -1*(1-4*pi.*((t-19.23e-9)/pw).^2).*exp(-2*pi.*((t-19.23e-9)/pw).^2)+ ... 1*(1-4*pi.*((t-25.64e-9)/pw).^2).*exp(-2*pi.*((t-25.64e-9)/pw).^2); %未调制脉冲对(yum) B=1; yum=B*y+ ... B*(1-4*pi.*((t-6.41e-9)/pw).^2).*exp(-2*pi.*((t-6.41e-9)/pw).^2)+ ... B*(1-4*pi.*((t-12.82e-9)/pw).^2).*exp(-2*pi.*((t-12.82e-9)/pw).^2)+ ... B*(1-4*pi.*((t-19.23e-9)/pw).^2).*exp(-2*pi.*((t-19.23e-9)/pw).^2)+ ... B*(1-4*pi.*((t-25.64e-9)/pw).^2).*exp(-2*pi.*((t-25.64e-9)/pw).^2); ym=yp+noise; %BPSK调制有噪脉冲对 yc=ym.*yum; %yc（相关输出）= ym（调制后）乘以yum（未调制）双峰。 % 这里是接收器中，进行互相关运算的地方，也就是接收器中的混频器。 % =====傅里叶变换，求频谱 % 对“BPSK转换后的脉冲对”进行傅里叶变换 NFFYM=2.^(ceil(log(length(ym))/log(2))); FFTYM=fft(ym,NFFYM); %序列末端补0 NumUniquePts=ceil((NFFYM+1)/2); FFTYM=FFTYM(1:NumUniquePts); MYM=abs(FFTYM); MYM=MYM*2; MYM(1)=MYM(1)/2; MYM(length(MYM))=MYM(length(MYM))/2; MYM=MYM/length(ym); f=(0:NumUniquePts-1)*2*Fn/NFFYM; % 对“未调制脉冲对(yum)”进行傅里叶变换 NFFYUM=2.^(ceil(log(length(yum))/log(2))); FFTYUM=fft(yum,NFFYUM);%pad with zeros NumUniquePts=ceil((NFFYUM+1)/2); FFTYUM=FFTYUM(1:NumUniquePts); MYUM=abs(FFTYUM); MYUM=MYUM*2; MYUM(1)=MYUM(1)/2; MYUM(length(MYUM))=MYUM(length(MYUM))/2; MYUM=MYUM/length(yum); f=(0:NumUniquePts-1)*2*Fn/NFFYUM; %new FFT for correlated pulses(yc) %yc is the time domain signal output of the multiplier %(modulated times unmodulated) in the correlation receiver. Plots %in the time domain show that a simple comparator instead of high speed A/D's %may be used to recover the 10101 signal depending on integrator design and level of %peak voltage into mixer. NFFYC=2.^(ceil(log(length(yc))/log(2))); FFTYC=fft(yc,NFFYC);%pad with zeros NumUniquePts=ceil((NFFYC+1)/2); FFTYC=FFTYC(1:NumUniquePts); MYC=abs(FFTYC); MYC=MYC*2; MYC(1)=MYC(1)/2; MYC(length(MYC))=MYC(length(MYC))/2; MYC=MYC/length(yc); f=(0:NumUniquePts-1)*2*Fn/NFFYC; end % =====阶段3：作图（plot） =====阶段3 for fold_stage=3:3 %plots for modulated doublet(ym) figure(1) subplot(1,2,1); plot(t,ym);xlabel('TIME');ylabel('AMPLITUDE'); title('Modulated pulse train'); grid on; %axis([-1e-9,27e-9 -1 2]) % subplot(1,2,2); plot(f,MYM);xlabel('FREQUENCY');ylabel('AMPLITUDE'); % %axis([0 10e9 0 .1]);%zoom in/out % grid on; subplot(1,2,2); plot(f,log10(MYM)-50);xlabel('FREQUENCY');ylabel('20LOG10=dBm'); %axis([0 20e9 -120 0]); grid on; % %plots for unmodulated doublet(yum) % figure(2) % subplot(2,2,1); plot(t,yum);xlabel('TIME');ylabel('AMPLITUDE'); % title('Unmodulated pulse train'); % grid on; % axis([-1e-9,27e-9 -1 1]) % subplot(2,2,2); plot(f,MYUM);xlabel('FREQUENCY');ylabel('AMPLITUDE'); % axis([0 10e9 0 .1]);%zoom in/out % grid on; % subplot(2,2,3); plot(f,20*log10(MYUM));xlabel('FREQUENCY');ylabel('20LOG10=DB'); % %axis([0 20e9 -120 0]); % grid on; %plots for correlated pulses(yc) % figure(3) % subplot(2,2,1); plot(t,yc);xlabel('TIME');ylabel('AMPLITUDE'); % title('Receiver correlator output-no LPF'); % grid on; % %axis([-1e-9,27e-9 -1 1]) % subplot(2,2,2); plot(f,MYC);xlabel('FREQUENCY');ylabel('AMPLITUDE'); % %axis([0 7e9 0 .025]);%zoom in/out % grid on; % subplot(2,2,3); plot(f,20*log10(MYC));xlabel('FREQUENCY');ylabel('20LOG10=DB'); % %axis([0 20e9 -120 0]); % grid on; % %=========================================================== % %CORRELATION RECEIVER COMPARATOR(before lowpass filter) % %=========================================================== % pt=.5%sets level where threshhold device comparator triggers % H=5;%(volts) % L=0;%(volts) % LEN=length(yc); % for ii=1:LEN; % if yc(ii)>=pt;%correlated output(y2) going above pt threshold setting % pv(ii)=H;%pulse voltage % else; % pv(ii)=L; % end; % end ; % po=pv;%pulse out=pulse voltage % % subplot(2,2,4); % plot(t,po); % axis([-1e-9 27e-9 -1 6]) % title('Comparator output'); % xlabel('Frequency'); % ylabel('Voltage'); % grid on; end % =====阶段4：相关接收机低通滤波器（积分器） =====阶段4 for fold_stage=4:0 rc=.2e-9;%time constant ht=(1/rc).*exp(-t/rc);%impulse response ht=.2e-9*ht;%I'm not sure about this.Reduces integrated output voltage greatly. ycfo=filter(yc,1,ht)/Fs;%use this instead of ycfo=conv(yc,ht)/Fs for proper dimension. %The #=1 allows this. The LPF RC time constant(integrates over this time). %Theory states that it should be set to the pulse width but should be set %to a value that gives the best error free operation at the highest noise %levels. Different filter types(butterworth,etc) may give different %results.I don't have the butter function. %The 3DB or 1/2 power bandwidth on the RC LPF is f=1/(2*pi*RC). The noise %bandwith is f=1/(4*rc). yn=filter(noise,1,ht)/Fs;%looks at filtered noise only(Figure 5) %new FFT for filtered correlated pulses(ycfo) NFFYCFO=2.^(ceil(log(length(ycfo))/log(2))); FFTYCFO=fft(ycfo,NFFYCFO);%pad with zeros NumUniquePts=ceil((NFFYCFO+1)/2); FFTYCFO=FFTYCFO(1:NumUniquePts);