www.pudn.com > chebshev.zip > Read_SP3.m, change:2013-04-09,size:5260b


function [Head_data,SP3_data]=Read_SP3
%读取精密星历文件中的数据
% global SP3_data
% global Head_data
[filename,filepath]=uigetfile('*.sp3','读取GPS精密星历文件');
fid=fopen(strcat(filepath,filename),'rt');
Head_data=struct;
SP3_data =struct;
if(fid==-1)
   msgbox('输入的文件或者路径不正确,无法正确打开sp3文件','警告信息');
   return;
end
% 读取文件头,并将其存入Head_data结构数组中
Head=[];
for i=1:22 %制度文件头的前16行
    line=fgetl(fid);
    Head=[Head;line];%将sp3文件的文件头以字符的形式显示出来,切记此处要保证sp3文件中的头文件的每行字符数是相同的,否则读取将失败
end
%提取文件头第一行的数据
Head_data.Version=Head(1,1:2);
Head_data.P_or_V=Head(1,3);
Head_data.start_year=str2num(Head(1,4:7));
Head_data.start_month=str2num(Head(1,9:10));
Head_data.start_day=str2num(Head(1,12:13));
Head_data.start_hour=str2num(Head(1,15:16));
Head_data.start_minute=str2num(Head(1,18:19));
Head_data.start_second=str2num(Head(1,21:31));
Head_data.EpochNum=str2num(Head(1,33:39));
Head_data.data_type=Head(1,41:45);
Head_data.Coordinate_system=Head(1,47:51);
Head_data.Orbit_type=Head(1,53:55);
Head_data.Institution=Head(1,57:60);
%第二行
Head_data.GPS_week=str2num(Head(2,4:7));
Head_data.FirstEpoch_weeksecond=str2num(Head(2,9:23));
Head_data.Epoch_interval=str2num(Head(2,25:38));
Head_data.MJD_zhengshu=str2num(Head(2,40:44));
Head_data.MJD_xiaoshu=str2num(Head(2,46:60));
%第三、四行-------提取观测卫星的PRN编号
Head_data.SatNum=str2num(Head(3,5:6));
PRN=strcat(Head(3,10:60),Head(4,10:60));
L=length(PRN)/3;
SP3_PRN=[];
for i=1:L
    Sp3_PRN=str2num(PRN((3*i-1):3*i));
    if Sp3_PRN==0
        continue;
    end
    SP3_PRN=[SP3_PRN Sp3_PRN];
end
Head_data.SP3_PRN=SP3_PRN;
%第八、九行-----提取相应卫星的精度
SatAccu=strcat(Head(8,10:60),Head(9,10:60));
L=length(SatAccu)/3;
SP3_SatAccu=[];
for i=1:L
    Sp3_SatAccu=str2num(SatAccu((3*i-1):3*i));
    if Sp3_SatAccu==0
        continue;
    end
    SP3_SatAccu=[SP3_SatAccu Sp3_SatAccu];
end
Head_data.SP3_SatAccu=SP3_SatAccu;
%第十五行-----读取标准差的浮点基数
Head_data.pos_jishu=str2num(Head(15,4:13));
Head_data.Satclock_jishu=str2num(Head(15,15:26));
%--------------------End of the reading of the Fileheader------------------

%--------------------读取卫星坐标及卫星钟钟差--------------------------------
%读取的卫星的三维坐标的单位为km,卫星钟差的单位为us
t=1;
while 1 
    line=fgetl(fid);
    result=findstr(line,'EOF');
    if(isempty(result))
        SP3_data(t).year=str2num(line(4:7));
        SP3_data(t).month=str2num(line(9:10));
        SP3_data(t).day=str2num(line(12:13));
        SP3_data(t).hour=str2num(line(15:16));
        SP3_data(t).minute=str2num(line(18:19));
        SP3_data(t).second=str2num(line(21:22));
        SP3_data(t).mm=SP3_data(t).hour*60+SP3_data(t).minute+ SP3_data(t).second/60;%将该历元的时分秒化为分钟,方便后面和观测历元比较
        SP3_data(t).TimeOEp=TimetoJD(SP3_data(t).year,SP3_data(t).month,SP3_data(t).day,SP3_data(t).hour,SP3_data(t).minute,SP3_data(t).second);%转换为儒略日
        for j=1:Head_data.SatNum
            line=fgetl(fid);
            SP3_data(t).PRN(j)=str2num(line(3:4));%将每个历元的卫星编号保存在一个数组中
            SP3_data(t).x(j)=str2num(line(5:18)); %提取卫星的三维坐标,单位为km
            SP3_data(t).y(j)=str2num(line(19:32));
            SP3_data(t).z(j)=str2num(line(33:46));
            SP3_data(t).Clock_corr(j)=str2num(line(47:60));%提取卫星钟差,单位为us
            %判断是否有坏的或空缺的位置值
%             if(SP3_data(t).x(j)==0||SP3_data(t).y(j)==0||SP3_data(t).z(j)==0)
%                 fprintf('注意:星历文件中的第%g个历元的%g号卫星的位置值是坏的或空缺的!\n',t,SP3_data(t).PRN(j));
%             end
%             %判断是否为坏的或空缺的钟差值
%             if(SP3_data(t).Clock_corr(j)==999999.999999)
%                 fprintf('注意:星历文件中的第%g个历元的%g号卫星的钟差值是坏的或空缺的!\n',t,SP3_data(t).PRN(j));
%             end
            %判断X的标准差是否为未知,若是将其置为0
            if(length(line)>=73 && isempty(str2num(line(62:63))))
                SP3_data(t).X_mi(j)=0;
            elseif(length(line)>=73 && ~isempty(str2num(line(62:63))))
                SP3_data(t).X_mi(j)=str2num(line(62:63));
            end
            %判断Y的标准差是否为未知,若是将其置为0
            if(length(line)>=73 && isempty(str2num(line(65:66))))
                SP3_data(t).Y_mi(j)=0;
            elseif(length(line)>=73 && ~isempty(str2num(line(65:66))))
                SP3_data(t).Y_mi(j)=str2num(line(65:66));
            end
            %判断Z的标准差是否为未知,若是将其置为0
            if(length(line)>=73 && isempty(str2num(line(68:69))));
                SP3_data(t).Z_mi(j)=0;
            elseif(length(line)>=73 && ~isempty(str2num(line(68:69))))
                SP3_data(t).Z_mi(j)=str2num(line(68:69));
            end
            %判断卫星钟差的标准差是否为未知,若是将其置为0
            if(length(line)>=73 && isempty(str2num(line(71:73))))
                SP3_data(t).Clock_mi(j)=0;
            elseif(length(line)>=73 && ~isempty(str2num(line(71:73))))
                SP3_data(t).Clock_mi(j)=str2num(line(71:73));
            end
        end
    elseif(~isempty(result))
        break;%判断读到文件的末尾,到达文件尾则退出
    end
    t=t+1;%记录文件体的行数
end
fclose(fid);