【信号跟踪】基于matlab二阶锁相环辅助三阶锁频环加码环高动态GNSS信号跟踪【含Matlab源码 2659期】.zip

clc; clear; %% 设置基本参数 middle_freq = 15.42e+6;%数字中频频率（下变频后频率） L1_frequency = 1575.42e6; dup_freq = 1000;%多普勒频率 sample_freq = 60e+6;%采样频率 code_freq = 10.23e+6;%CB1码率 code_length = 1023;%伪码周期 snr = 37;%载噪比 FLL_bandwidth = 30; PLL_bandwidth = 18;%PLL噪声带宽 DDLL_bandwidth = 30;%码环滤波噪声带宽 nco_Length = 32;%载波NCO及码NCO位宽 noise_std = 1; sample_t = 1/sample_freq;%采样频率 K = 1;%环路增益 transfer_coef = (2^nco_Length)/sample_freq;%频率字转换系数 middle_freq_nco = middle_freq*transfer_coef;%中频对应的频率字 Ncoh = (sample_freq / code_freq)*code_length;%一个积分清除时间内的采样点数 Tcoh = Ncoh *sample_t;%积分清除时间 dot_length = [1:Ncoh];%一个积分清除时间内的采样点数 code_word = code_freq * transfer_coef;%码环控制字 FLL_DLL_rate = 1/154;%码环动态与载波动态比率系数（码率/载波频率） fd_code = dup_freq*FLL_DLL_rate*transfer_coef;%添加在信号源的码多普勒，体现在码NCO上 % fd_code = 0;%添加在信号源的码上的多普勒，体现在码NCO上 e_code_original_phase = (2^nco_Length)/2;%本地超前码的初相位，相当于提前了1/2个码片 modulate_code_bias_phsae = (2^nco_Length)/2;%输入信号源初相位，相当于提前了1/2个码片 signal_phase = 0; local_phase = 0; fll_nco_adder = 0; carrier_nco_sum = 0;%本地载波初始相位 pll_nco_adder = 0;%锁相环产生的载波频率调整控制字 code_nco_sum = 0; code_nco_adder = 0;%码环码相位调整控制字 n = 3; n_IQ = 2; I_P_final(1:n_IQ) = 0; Q_P_final(1:n_IQ) = 0; output_fll(2:3) = 0; output_filter_fll(1:3) = 0;%初始化锁频环环路滤波器输出 output_filter_pll(1:3) = 0;%初始化锁相环环路滤波器输出 output_pll(2:3) = 0; output_filter_ddll(1:3) = 0;%初始化码环环路滤波器输出 pll_after_filter = 0; signal_input_all = [];%记录所有的输入信号并写入外部文档 loop_count = 0; %% 设置环路滤波器参数 WnP = 1.27 * PLL_bandwidth; %锁相环路的自然频率 WnD = 1.89 * DDLL_bandwidth; %码环环路滤波器的自然角频率 WnF = 1.89 * FLL_bandwidth;%锁频环路的自然频率 carrier_k=0.25;%载波增益 cofeone_PLL = (2*WnP+2*WnP^2*Tcoh+WnP^3*Tcoh^2)/carrier_k; cofetwo_PLL = -(4*WnP+2*WnP^2*Tcoh)/carrier_k; cofethree_PLL = 2*WnP/carrier_k; cofeone_DDLL = (sqrt(2)*WnD+WnD^2*Tcoh)/K; cofetwo_DDLL = -sqrt(2)*WnD/K; cofeone_FLL = (sqrt(2)*WnF*Tcoh+WnF^2*Tcoh^2)/carrier_k; cofetwo_FLL = -(sqrt(2)*WnF*Tcoh)/carrier_k; PLL_flag = 0; %% 下变频滤波器 fd = [3190000 5190000 25650000 27650000]; %过渡带 mag = [0 1 0]; dev = [0.05 0.015 0.05]; [n2,wn,beta,ftype] = kaiserord(fd,mag,dev,sample_freq); b = fir1(n2,wn,ftype,kaiser(n2+1,beta)); %% 产生GOLD码表 G1 = ones(1,10); %G1初始值 G2 =ones(1,10); %G2初始值 c_out = []; %C/A码 c_out(1:10) = [1 0 0 1 0 1 1 0 1 1]; %PRN号码为5的C/A码前十个比特 for i = 1:1023 if(i>10) c_out(i) = mod((G1(10) + G2(1) + G2(9)),2); %PRN为5号，抽头选择1xor9 end temp = xor(G1(3),G1(10)); %G1多项式 G1(2:10) = G1(1:9); G1(1) = temp; temp = mod((G2(2)+G2(3)+G2(6)+G2(8)+G2(9)+G2(10)),2); %G2多项式 G2(2:10) = G2(1:9); G2(1) = temp; end % fid=fopen('D:\Xilinx\Vivado\vivado_results\GPS_tracking\ca_table.coe','w'); % fprintf(fid,'memory_initialization_radix=10;\n'); % fprintf(fid,'memory_initialization_vector=\n'); % for i = 1 : 1022 % fprintf(fid, '%d,\n', c_out(i)); % end % fprintf(fid, '%d;', c_out(1023)); % fclose(fid); code_table=(c_out-0.5)*2;%变成正负1的电平模式 %% 初始提前码 early_code_temp=[]; early_code_nco = e_code_original_phase; for init=1:Ncoh early_code_nco = early_code_nco+ code_word ; early_code_nco = mod(early_code_nco,2^32*1023); index=1+fix(early_code_nco/2^32); c=code_table(index); early_code_temp=[early_code_temp,c]; end local_early_code_last=early_code_temp; %% 跟踪 for loop_num = 1 : 1000 dot_length = dot_length+Ncoh; fd_plot(loop_num) = dup_freq;%真实多普勒频偏 fd_code_dup(loop_num) = fd_code/transfer_coef; flag(loop_num) = PLL_flag; %% 产生输入码信号 signal_modulate_code=[]; modulate_code_nco = modulate_code_bias_phsae;%输入码信号初始相位 for i=1:Ncoh modulate_code_nco = modulate_code_nco + code_word + fd_code;%码频率字 + 多普勒频率字 modulate_code_nco = mod(modulate_code_nco,2^32*1023);%不超过一个码周期，2^32 代表一个码片，1023码片是一个周期 index = 1+fix(modulate_code_nco/2^32);%当超过2^32，进位到下个码片 c = code_table(index);%查码表 signal_modulate_code = [signal_modulate_code,c]; if 1 == i signal_phase = modulate_code_nco/2^32*360; end end %% 码信号与载波相乘作为输入信号 signal_original = cos(2*pi*(L1_frequency + dup_freq )*dot_length*sample_t);%初始载波信号 signal_amplitude = sqrt(10^(snr/10)*(noise_std^2*2));%根据信噪比扩大幅值 noise = noise_std*rand(1,Ncoh);%噪声 receive_signal = signal_amplitude*signal_modulate_code.* signal_original + noise;%将C/A码调制在载波上并添加信道噪声 receive_signal = receive_signal/(max(abs(receive_signal)));%将输入数据归一化 % receive_signal = filter(b,1,receive_signal); signal_input_all = [signal_input_all,receive_signal];%记录输入信号并导出 %% 产生本地载波 for demond_num = 1:Ncoh local_cos(demond_num) = cos(2*pi*carrier_nco_sum/2^nco_Length);%本地cos local_sin(demond_num) = -sin(2*pi*carrier_nco_sum/2^nco_Length);%本地sin carrier_nco_sum = carrier_nco_sum + middle_freq_nco + pll_nco_adder + fll_nco_adder;%本地载波NCO控制字 end %% 产生本地码 code_nco_sum = code_nco_adder + code_word + fll_nco_adder*FLL_DLL_rate; %本地码环NCO控制字 %产生本地超前，即时，滞后码 code_temp = []; for local_init=1:Ncoh early_code_nco = early_code_nco + code_nco_sum; early_code_nco = mod(early_code_nco,2^32*1023); index = 1 + fix(early_code_nco/2^32); c = code_table(index); code_temp = [code_temp,c]; if 1 == local_init local_phase = early_code_nco/2^32*360; end end local_early_code = code_temp; local_prompt_code = [local_early_code_last(Ncoh-2:Ncoh),local_early_code(1:Ncoh-3)]; local_late_code = [local_early_code_last(Ncoh-4:Ncoh),local_early_code(1:Ncoh-5)]; local_early_code_last = local_early_code; %% 载波解调与信号解码 %载波解调 I_demon_carrier = local_cos.*receive_signal; Q_demon_carrier = local_sin.*receive_signal; %信号解码并积分清除 I_E_final = sum(I_demon_carrier.*local_early_code); Q_E_final = sum(Q_demon_carrier.*local_early_code); I_P_final(n_IQ) = sum(I_demon_carrier.*local_prompt_code); Q_P_final(n_IQ) = sum(Q_demon_carrier.*local_prompt_code); I_L_final = sum(I_demon_carrier.*local_late_code); Q_L_final = sum(Q_demon_carrier.*local_late_code); % if 1 == loop_num % I_P_final(n_IQ - 1) = I_P_final(n_IQ); % Q_P_final(n_IQ - 1) = Q_P_final(n_IQ); % end %% 锁频环 dot_fll = I_P_final(n_IQ - 1) * I_P_final(n_IQ) + Q_P_final(n_IQ - 1) * Q_P_final(n_IQ); cross_fll = I_P_final(n_IQ - 1) * Q_P_final(n_IQ) - I_P_final(n_IQ) * Q_P_final(n_IQ - 1); output_fll(n) = atan2(cross_fll,dot_fll)/(Tcoh*2*pi); result_discriminator_Fll(loop_num) = output_fll(n); output_filter_fll(n) = (cofeone_FLL * output_fll(n)) + (cofetwo_FLL * output_fll(n - 1)) + (2 * output_filter_fll(n - 1)) - output_filter_fll(n - 2); fll_after_filter(loop_num) = output_filter_fll(n);%记录锁频环环路滤波器输出 fll_nco_adder = output_filter_fll(n) * transfer_coef ; %频率字转换 output_fll(n - 1)=output_fll(n); output_filter_fll(n - 2)=output_filter_fll(n - 1); output_filter_fll(n - 1)=output_filter_fll(n); %% 是否启动锁相环 PLL_flag = 1; % if 0 == PLL_flag && abs(output_fll(n))<50 %本地频差小于100启动锁相环 % loop_count = loop_count + 1; % if loop_count>100 % PLL_flag = 1; % end % elseif 1 == PLL_flag && abs(output_fll(n))>50 %�