96 lines
3.9 KiB
Matlab
96 lines
3.9 KiB
Matlab
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% Lucas Ward
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% ASEN 5090
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% Read the RINEX navigation file. The header is skipped because
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% information in it (a0, a1, iono alpha and beta parameters) is not
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% currently needed for orbit computation. This can be easily amended to
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% include navigation header information by adding lines in the 'while' loop
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% where the header is currently skipped.
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%
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% Input: - filename - enter the filename to be read. If filename
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% exists, the orbit will be calculated.
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%
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% Output: - ephemeris - Output is a matrix with rows for each PRN and
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% columns as follows:
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%
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% col 1: PRN ....... satellite PRN
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% col 2: M0 ....... mean anomaly at reference time
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% col 3: delta_n ..... mean motion difference
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% col 4: e ....... eccentricity
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% col 5: sqrt(A) ..... where A is semimajor axis
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% col 6: OMEGA ....... LoAN at weekly epoch
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% col 7: i0 ....... inclination at reference time
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% col 8: omega ....... argument of perigee
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% col 9: OMEGA_dot ... rate of right ascension
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% col 10: i_dot ....... rate of inclination angle
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% col 11: Cuc ....... cosine term, arg. of latitude
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% col 12: Cus ....... sine term, arg. of latitude
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% col 13: Crc ....... cosine term, radius
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% col 14: Crs ....... sine term, radius
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% col 15: Cic ....... cosine term, inclination
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% col 16: Cis ....... sine term, inclination
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% col 17: toe ....... time of ephemeris
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% col 18: IODE ....... Issue of Data Ephemeris
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% col 19: GPS_wk ....... GPS week
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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function ephemeris = read_rinex_nav( filename )
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fid = fopen(filename);
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if fid == -1
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errordlg(['The file ''' filename ''' does not exist.']);
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return;
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end
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% skip through header
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end_of_header = 0;
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while end_of_header == 0
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current_line = fgetl(fid);
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if strfind(current_line,'END OF HEADER')
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end_of_header=1;
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end
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end
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j = 0;
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while feof(fid) ~= 1
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j = j+1;
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current_line = fgetl(fid);
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% parse epoch line (ignores SV clock bias, drift, and drift rate)
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[PRN, Y, M, D, H, min, sec,af0,af1,af2] = parsef(current_line, {'I2' 'I3' 'I3' 'I3' 'I3' 'I3' ...
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'F5.1','D19.12','D19.12','D19.12'});
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% Broadcast orbit line 1
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current_line = fgetl(fid);
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[IODE Crs delta_n M0] = parsef(current_line, {'D22.12' 'D19.12' 'D19.12' 'D19.12'});
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% Broadcast orbit line 2
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current_line = fgetl(fid);
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[Cuc e Cus sqrtA] = parsef(current_line, {'D22.12' 'D19.12' 'D19.12' 'D19.12'});
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% Broadcast orbit line 3
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current_line = fgetl(fid);
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[toe Cic OMEGA Cis] = parsef(current_line, {'D22.12' 'D19.12' 'D19.12' 'D19.12' 'D19.12'});
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% Broadcast orbit line 4
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current_line = fgetl(fid);
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[i0 Crc omega OMEGA_dot] = parsef(current_line, {'D22.12' 'D19.12' 'D19.12' 'D19.12' 'D19.12'});
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% Broadcast orbit line 5
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current_line = fgetl(fid);
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[i_dot L2_codes GPS_wk L2_dataflag ] = parsef(current_line, {'D22.12' 'D19.12' 'D19.12' 'D19.12' 'D19.12'});
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% Broadcast orbit line 6
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current_line = fgetl(fid);
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[SV_acc SV_health TGD IODC] = parsef(current_line, {'D22.12' 'D19.12' 'D19.12' 'D19.12' 'D19.12'});
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% Broadcast orbit line 7
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current_line = fgetl(fid);
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[msg_trans_t fit_int ] = parsef(current_line, {'D22.12' 'D19.12' 'D19.12'});
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[ gps_week, toc ] = UTC2GPST(Y, M, D, H, min, sec);
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ephemeris(j,:) = [PRN, M0, delta_n, e, sqrtA, OMEGA, i0, omega, OMEGA_dot, i_dot, Cuc, Cus, Crc, Crs, Cic, Cis, toe, IODE, GPS_wk,toc,af0,af1,af2,TGD];
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end
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