遥测遥控实验报告4

遥测遥控技术实验四

学院电子工程学生姓名：严丰班级学号：2902107014 指导老师：李晋

一、实验名称：GPS信号跟踪原理与仿真

二、实验程序：

主程序：

function

[diata_dll,diata_fll]=tracksignal(iniphcode,inifd,iniph,snr,Code_Method_flag,Carrier_Meth od_flag,codew,codeb,carrierw,carrierfllb,carrierpllb)

svnum = 10; %卫星号

iniphcode = 500; %生成信号源的码相位

inifd = 3000; %生成信号源的载波多普勒频率

iniph = 5; %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

codew = 20 %自然圆频率

codeb = 2 %阻尼系数

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

carrierw = 20 %自然圆频率

carrierfllb = 0.707 %阻尼系数

carrierpllb = 0.706

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