matlab通信仿真：27 GPS相关读取跟踪和捕获案例.zip

function [diata_dll,diata_fll]=tracksignal(iniphcode,inifd,iniph,snr,Code_Method_flag,Carrier_Method_flag,codew,codeb,carrierw,carrierfllb,carrierpllb) svnum = 10; %卫星号 %iniphcode = 120; %生成信号源的码相位 %inifd = 4600; %生成信号源的载波多普勒频率 %iniph = 0; %生成信号源的载波初相位 %snr = 0; %生成信号源的信噪比 global time_unit; % 数据跳变时间单位 global time; % 数据发送时间 global time_cyc;% 一个完整扩频码周期 global fs; % 采样率 global nn; % 一个完整扩频周期采样点数 global kk; % 数据总采样点 global F_if; % 载波中频 global CA_freq; % PN码速率 global tc; global CA ; % 扩频码基玛 global F_Carrier; % L1波段载波频率 %%%%%%%%%%%%%%%%%%%%%%%%参数设置%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% time = 100*(10^(-3)); time_unit = 20*(10^(-3)); time_cyc = 1*(10^(-3)); fs = 5*(10^6); nn = time_cyc*fs; kk = (time/time_cyc)*nn; F_if = 1.25*(10^6); F_Carrier = 1575.42*(10^6); CA_freq = 1.023*(10^6); %%%%%%%%%%%生成C/A以供使用%%%%%%%%%% PN = codegen(svnum); CA = []; k = 5; for n = 1:length(PN) CA((1+k*(n-1)):k*n) = PN(n)*ones(1,k); end tc = 1/(k*CA_freq); loop_time = time/time_cyc; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%生成信号源 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %Signal_Source是生成的信号源, buffer_bit_data是随机生成的数据位，用于与最后解调的数据进行比对 [Signal_Source,Phase_signal,buffer_bit_data]=CreateSource(iniphcode,inifd,iniph,snr); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%捕获%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [fd_ac,f_ac_code] = acqu(Signal_Source); %%%%%%%%%%%%%%%%%%%%%%%%%%%%定义跟踪中用到的参数%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% IPSum_old = 0.01; QPSum_old = 0.01; %%%%%%%%%%码跟踪环滤波器参数设置%%%%%%%%%%%%%% %Code_Method_flag=2; %码跟踪环鉴相法选择标志 diffoffside = 0.5; %码鉴相时，正负偏移半个码片 k0 =10^(-6); %码跟踪环鉴相器增益 k1=10^(-3); %码跟踪环NCO增益 %k1 = 50/k0; %码跟踪环NCO增益 offside = f_ac_code; theta_code_old = 0; offside_old = f_ac_code; CodeErr_old = 0; Bk_DLL = []; Track_Code_Buffer =[]; %%%%%%%%%%%载波跟踪环滤波器参数设置%%%%%%%%%% Last_Phase = 0; Control_Buffer = []; ts = 1/fs; %采样时间间隔 %Carrier_Method_flag =3; %fll,pll,fll->pll的方法选择标志 dem_flag = 0; %fll->pll的切换标志 add = 0; %fll->pll的切换过程中用到的变量 Track_Freq_Buffer = []; track_dopplar_old = 0; %FLL环参数 FLLinput_old=0; FLLoutput_old=0; track_freq_fll = 0; Sita_fll = 0; Bk_FLL = []; %PLL环参数 PLLinput_old=0; PLLoutput_old=0; track_freq_pll = 0; Sita_pll = 0; Bk_PLL = []; Buffer_Data =[]; adj_buffer = []; ALL_Buffer_Data = []; count_buffer = []; Demodulate_I = []; Local_Ph_Buffer = []; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%跟踪循环%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% for i = 1:1:loop_time % =================part signal source========= % Signal = Signal_Source((i-1)*nn+1:i*nn); % Signalph= Phase_signal((i-1)*nn+1:i*nn); %==============Local carrier===================% t = [0:nn-1]*ts; track_dopplar = fd_ac+track_freq_fll+track_freq_pll; Track_Freq_Buffer = [Track_Freq_Buffer track_dopplar]; Local_I = cos(2*pi*(F_if+track_dopplar)*t + Last_Phase); Local_Q = sin(2*pi*(F_if+track_dopplar)*t + Last_Phase); Iph = 2*pi*(F_if+track_dopplar)*t + Last_Phase; Local_Ph_Buffer = [Local_Ph_Buffer Iph]; Last_Phase = Last_Phase + 2*pi*(F_if+track_dopplar)*time_cyc; %%上一次积分结束点的相位 Carrier_I = Local_I; Carrier_Q = Local_Q; % =================Create Localcode============== % ph_code_p = offside; fd_code_p = track_dopplar; CA_Code_p = CAcode(ph_code_p,fd_code_p,i); lc_p = CA_Code_p.*Signal; ph_code_e = offside+diffoffside; fd_code_e = track_dopplar; CA_Code_e = CAcode(ph_code_e,fd_code_e,i); lc_e = CA_Code_e.*Signal; ph_code_l = offside-diffoffside; fd_code_l = track_dopplar; CA_Code_l = CAcode(ph_code_l,fd_code_l,i); lc_l = CA_Code_l.*Signal; % ==========================multiply================================ % Local_P_I = lc_p.*Carrier_I; Local_P_Q = lc_p.*Carrier_Q; Local_E_I = lc_e.*Carrier_I; Local_E_Q = lc_e.*Carrier_Q; Local_L_I = lc_l.*Carrier_I; Local_L_Q = lc_l.*Carrier_Q; % ========================integration============================= % IPSum = sum(Local_P_I); QPSum = sum(Local_P_Q); IESum = sum(Local_E_I); QESum = sum(Local_E_Q); ILSum = sum(Local_L_I); QLSum = sum(Local_L_Q); % =======================Code Control================================== if Code_Method_flag==1 %鉴想器 theta_code = k0*((IESum.^2+QESum.^2)-(ILSum.^2+QLSum.^2)); %码环路滤波器 [CodeErr] = CodeloopFilter(codew,codeb,theta_code,theta_code_old,CodeErr_old); %CodeErr是经过滤波器输出的码相位误差的估计值 %码环NCO offside=offside_old+60*k1*CodeErr; %码NCO的输出 theta_code_old = theta_code; %将当前结果保存，用于下一个循环的码跟踪 CodeErr_old = CodeErr; %将当前结果保存，用于下一个循环的码跟踪 offside_old = offside; %将当前结果保存，用于下一个循环的码跟踪 Bk_DLL = [Bk_DLL theta_code]; %记录跟踪过程中的码环鉴想器的输出 Track_Code_Buffer = [Track_Code_Buffer offside]; %记录跟踪过程中的码环NCO的数出 elseif Code_Method_flag==2 %鉴想器 theta_code = ((IESum.^2+QESum.^2)-(ILSum.^2+QLSum.^2))/((IESum.^2+QESum.^2)+(ILSum.^2+QLSum.^2)); theta_code =10.^(-3)*(1-sqrt(1-theta_code.^2))/(2*theta_code); %码环路滤波器 [CodeErr] = CodeloopFilter(codew,codeb,theta_code,theta_code_old,CodeErr_old); %CodeErr是经过滤波器输出的码相位误差的估计值 %码环NCO offside=offside_old+500*CodeErr; %码NCO的输出 theta_code_old = theta_code; %将当前结果保存，用于下一个循环的码跟踪 CodeErr_old = CodeErr; %将当前结果保存，用于下一个循环的码跟踪 offside_old = offside; %将当前结果保存，用于下一个循环的码跟踪 Bk_DLL = [Bk_DLL theta_code]; %记录跟踪过程中的码环鉴想器的输出 Track_Code_Buffer = [Track_Code_Buffer offside]; %记录跟踪过程中的码环NCO的数出 end % ====================Carrier control=============================% if Carrier_Method_flag == 1 %%%%%%%%%%%%%%% fll跟踪环路 %鉴想器 real_Q = IPSum_old*QPSum-QPSum_old*IPSum; real_I = IPSum_old*IPSum+QPSum_old*QPSum; a=real_Q/real_I; theta_fll = atan(real_Q/real_I); Bk_FLL = [Bk_FLL theta_fll]; FLLinput = theta_fll/(2*pi*time_cyc); %环路滤波器 FLLoutput = CarrierLoopFilter(carrierw,carrierfllb/2,FLLinput,FLLinput_old,FLLoutput_old); %FLL环NCO Sita_fll = Sita_fll+FLLoutput; track_freq_fll = -Sita_fll; %FLL环跟踪到的多普勒频率 (由于反正切主值区间造成的) FLLinput_old=FLLinput; %将当前结果保存，用于下一个循环的载波跟踪 FLLoutput_old=FLLoutput; %将当前结果保存，用于下一个循环的载波跟踪 IPSum_old = IPSum; %将当前结果保存，用于下一个循环的载波跟踪 QPSum_old = QPSum; %将当前结果保存，用于下一个循环的载波跟踪 elseif Carrier_Method_flag == 2 %%%%%%%%%%%%%%%%%%%%%%%costa跟踪环路 theta_pll = atan(QPSum/IPSum); PLLinput = theta_pll/(2*pi*time_cyc); Bk_PLL = [Bk_PLL theta_pll]; %LoopFilter PLLoutput = CarrierLoopFilter(carrierw,carrierpllb/2,PLLinput,PLLinput_old,PLLoutput_old); track_freq_pll = -PLLoutput; PLLinput_old=PLLinput; %将当前结果保存，用于下一个循环的载�