gps跟踪中的伪码相位，很好用的，可以下载下来

% % 本程序用于实现扩频系统信号跟踪中，码相位的跟踪 % 输入信号为，载波锁定之后的多普勒频率和码相位 % 目前实际多普勒频率1000，相位952 function Catched = PN_Phase_Trace(fd_estimate, Correl_Peak_location_real) % 获取系统参数 [code_cycle,SNR,Ts,T,T_interp,fi,M,N,fd,f0,delay_time,fd_estimate_init,sigma_n,fs,Bandwidth,dot_insert,coef,coef_mod,B,A1]=set_parameter; %%%%产生接受中频信号伪码，抽头为1，8 code_phase=[1,8]; [inputcode]=code_gen(code_phase); % 1023大小的GOLD伪码 %%%%本地伪码 native_code=inputcode; inputcode_2=[native_code,native_code]; EmulateIndex = 0; k = 0; half_dot_insert = dot_insert/2; ThisPN = zeros(1, N); % 本次即时码 EarlyPN2 = zeros(1, N); % 超前码 LagPN2 = zeros(1, N); % 滞后码 const4 = fix(N/(4*1023)); % 超前、滞后1/4，需要移动的抽样点 const8 = fix(N/(8*1023)); % 超前、滞后1/8，需要移动的抽样点，当采样为5808点时，无法采用 Correl_Peak_location_real = Correl_Peak_location_real*5808/1023; while (1) % 模拟输入的中频信号 EmulateIndex = EmulateIndex + 1; [signal,signal_noise]=SignalGenerator(EmulateIndex,inputcode,fs,Ts,fi,delay_time,fd,SNR,Bandwidth,code_cycle,sigma_n,f0,N); IF_signal(1:N)=signal(1:N); IF_signal_noise(1:N)=signal_noise(1:N); % % 绘制信号及噪声 % figure(1); % plot(IF_signal, 'b'); % 绘制生成的信号(含噪声) % hold on; % plot(IF_signal_noise, 'r'); % 信号的噪声 % hold off; % 当前的载波NCO ××× fd_estimate在不断调整 [NCO_I_Quanti,NCO_Q_Quanti]=Nco_gen(Ts,fi,fd_estimate,N); % 下变频 Rece_Signal_Quan_down_I = IF_signal(1:N).* NCO_I_Quanti; Rece_Signal_Quan_down_Q = IF_signal(1:N).* NCO_Q_Quanti; Rece_Signal_Quan_down_I_noise=IF_signal_noise.*NCO_I_Quanti; Rece_Signal_Quan_down_Q_noise=IF_signal_noise.*NCO_Q_Quanti; %%%%经过低通滤波器，截止频率为1.023MHz [signal_I,signal_Q,signal_I_noise,signal_Q_noise]=LP_filter(N,N+1,code_cycle,fs,Rece_Signal_Quan_down_I,Rece_Signal_Quan_down_Q,Rece_Signal_Quan_down_I_noise,Rece_Signal_Quan_down_Q_noise,EmulateIndex); %进过低通滤波器 % % 绘制比较，低通滤波器的作用 % figure(2); % plot(Rece_Signal_Quan_down_I, 'b'); % 原始 % hold on % plot(signal_I, 'r'); % % hold off % 这次不再内插成4096个点，而是保持5808个抽样点，表示一个码字长度的值 ThisPN = PN2Generator(inputcode,Correl_Peak_location_real,N); % 相关间隔1/2 % 超前码1/4 EarlyPN2 = [ThisPN((const4+1):N) ThisPN(1:const4)]; % 滞后码 LagPN2 = [ThisPN((N-const4):N) ThisPN(1:(N-const4-1))]; % 相关间隔1/4 % 超前码1/8 EarlyPN4 = [ThisPN((const8+1):N) ThisPN(1:const8)]; % 滞后码 LagPN4 = [ThisPN((N-const8):N) ThisPN(1:(N-const8-1))]; k = k+1; % 积分器，算出I.Q Ips(k) = sum(ThisPN.*Rece_Signal_Quan_down_I); Qps(k) = sum(ThisPN.*Rece_Signal_Quan_down_Q); Ies2(k) = sum(EarlyPN2.*Rece_Signal_Quan_down_I); Qes2(k) = sum(EarlyPN2.*Rece_Signal_Quan_down_Q); Ils2(k) = sum(LagPN2.*Rece_Signal_Quan_down_I); Qls2(k) = sum(LagPN2.*Rece_Signal_Quan_down_Q); % Ies4(k) = sum(EarlyPN4.*Rece_Signal_Quan_down_I); % Qes4(k) = sum(EarlyPN4.*Rece_Signal_Quan_down_Q); % % Ils4(k) = sum(LagPN4.*Rece_Signal_Quan_down_I); % Qls4(k) = sum(LagPN4.*Rece_Signal_Quan_down_Q); % 伪码相位误差 % 归一化点积鉴项器-斜率2 EC1(k) = ((Ies2(k)-Ils2(k))*Ips(k) + (Qes2(k)-Qls2(k))*Qps(k))/(Ips(k)*Ips(k) + Qps(k)*Qps(k));% % if(EC1(k) > 2) % EC1(k) = 2; % end; % if (EC1(k) < -2) % EC1(k) = -2; % end; % 归一化超前减滞后功率鉴项器-斜率4 % EC2(k) = (Ies4(k)*Ies4(k)+Qes4(k)*Qes4(k)-Ils4(k)*Ils4(k)-Qls4(k)*Qls4(k))/(Ies4(k)*Ies4(k)+Qes4(k)*Qes4(k)+Ils4(k)*Ils4(k)+Qls4(k)*Qls4(k)); % 计算相位差 diff1 = EC1(k)*5808/1023/2; DiffFilter(k) = EC1(k)*5808/1023/2; if(k > 128) DiffFilter(k) = sum(DiffFilter(k-127:k))/128; if(DiffFilter(k) < 1/24) Catched = 1; disp('码相位已经跟踪并锁定'); Correl_Peak_location_real %break; end; end; % diff2 = EC2(k)/4; % 使用滤波 if(abs(DiffFilter(k)) < 1) PhaseQueue(k) = Correl_Peak_location_real; else PhaseQueue(k) = Correl_Peak_location_real+round(DiffFilter(k)); if(PhaseQueue(k) >= 5808) PhaseQueue(k) = mod(PhaseQueue(k),5808) + 1;%*1023 end; end; % % 未加滤波 % if(abs(diff1) < 1) % PhaseQueue(k) = Correl_Peak_location_real; % else % PhaseQueue(k) = Correl_Peak_location_real+round(diff1); % if(PhaseQueue(k) >= 5808) % PhaseQueue(k) = mod(PhaseQueue(k),5808) + 1;%*1023 % end; % end; Correl_Peak_location_real = PhaseQueue(k); PhaseQueue(k) = fix(PhaseQueue(k)*1023/5808); %Correl_Peak_location_real = mod(Correl_Peak_location_real +1,1023) + 1; % if abs(diff1+diff2)/2 < 0. % end; if(mod(length(PhaseQueue),200)==0) % 绘制伪码相位跟踪的结果 figure(91); plot(PhaseQueue); end; end