%GPS Toolbox %Version 1.1 09-Dec-1997 % %Directory: proc_dd % %ACCUM0 Accumulates the contribution of observations from one epoch. The % result is output under the same name. % %ANHEADER Analyzes the header of a RINEX file and outputs the list of % observation types and antenna offset. End of file is flagged 1, % else 0. Likewise for the types. % Typical call: anheader('pta.96o') % %B_POINT Prepares input to the Bancroft algorithm for finding a % preliminary position of a receiver. The input is four or more % pseudoranges and the coordinates of the satellites. % %BACKTRAC backtrack in the search tree; used in SEARCH % %BANCROFT Calculation of preliminary coordinates for a GPS receiver % based on pseudoranges to 4 or more satellites. The ECEF % coordinates (see function e_r_corr) are the first three elements % of each row of B. The fourth element of each row of B contains % the observed pseudorange. Each row pertains to one satellite. % The pseudorange in the first row of B is used to descriminate % between the two possible solutions. % Reference: Bancroft, S. (1985) An Algebraic Solution of the GPS % Equations, IEEE Trans. Aerosp. and Elec. Systems, AES-21, % 56--59 % %CALL_LAM Call of the LAMBDA routines for integer estimation of the GPS % double difference ambiguities % %CHECK_T repairs over- and underflow of GPS time % %CHISTART computes squared distance of partially rounded float vectors to % the float vector in the metric of the covariance matrix. % %COLLECTS collects integer vectors and corresponding squared distances % %DOUT spools vector to a file % %DOY Calculation of day number of year. hour is split into hr, min, % and sec % %E_R_CORR Returns rotated satellite ECEF coordinates due to Earth rotation % during signal travel time % %ENU2XYZ Transformation of [e;n;u] vector from local to geocentric system. % The local system has origin at (phi, lambda) % %FEPOCH_0 Finds the next epoch in an opened RINEX file with identification % fid. From the epoch line is produced time (in seconds of week), % number of sv.s, and a mark about end of file. Only observations % with epoch flag 0 are delt with. % %FIND_EPH Finds the proper column in ephemeris array % %FOBS_TYP Returns column i of the observation matrix which contains % observation type "type" % %FRGEOD Subroutine to calculate Cartesian coordinates X,Y,Z given % geodetic coordinates latitude, longitude (east), and height above % reference ellipsoid along with reference ellipsoid values % semi-major axis a and the inverse of flattening finv. % The units of linear parameters h,a must agree (m,km,mi,..etc). % The input units of angular quantities must be in decimal degrees. % The output units of X,Y,Z will be the same as the units of h % and a. % %GET_EPH The ephemerides contained in ephemeridesfile are reshaped into a % matrix with 21 rows and as many columns as there are ephemerides. % Typical call eph = get_eph('rinex_n.dat') % %GET_RHO Calculation of distance in ECEF system between satellite and % receiver at time tR_RAW given the ephemeris Eph. % %GPS_TIME Conversion of Julian Day number to GPS week and Seconds of Week % reckoned from Saturday midnight % %GRABDATA Positioned in a RINEX file at a selected epoch reads observations % of NoSv satellites % %INTOUT spools integer vector to a file % %JULDAY Conversion of date as given by % y ... year (four digits) % m ... month % d ... day % h ... hour and fraction hereof % The conversion is only valid in the time span from March 1900 to % February 2100. % See Hofmann-Wellenhof et al., p. 41--42 % %L_INV computes the inverse of a lower triangular matrix % %LAMBDA integer estimation with the LAMBDA method. It is first % described in % % Teunissen P.J.G. (1993). Least-squares estimation of the integer % GPS ambiguities. Invited lecture. Section IV Theory and % Methodology. General Meeting of the International Association % of Geodesy. Beijing, China. August 1993. % % Implementational aspects of the method are well described in % % Jonge P.J. de and C.C.J.M. Tiberius (1996). The LAMBDA method % for integer ambiguity estimation: implementation aspects. % Publication of the Delft Geodetic Computing Centre, LGR-series % No. 12. August 1996. 49 pp. % On Internet: http://www.geo.tudelft.nl/mgp/ % under 'Precise GPS positioning' (available as PostScript file) % %LOCATE For a given iprn_value we find the component number iloc for the % satellite in the vector of unknowns % %LORENTZ Calculates the Lorentz inner product of the two 4 by 1 vectors x % and y % %LTDL factorization of Q into L^T D L % %PROC_DD Processing of double differenced GPS data as read from RINEX % files % Typical call: proc_dd('site1.96o','site2.96o','site1.nav') % %RE_ORDER Computation of the Z-transformation matrix. The final % Z-transformation is constructed from a sequence of interchanges % of two neighbouring ambiguities (this function) and integer % Gauss transformations (function ztransi) that decorrelate the % ambiguities. % %RINEXE Reads a RINEX Navigation Message file and reformats the data into % a matrix with 21 rows and a column for each satellite. The % matrix is stored in outputfile. % Typical call: rinexe('pta.96n','pta.nav') % %SATPOS Calculation of X,Y,Z coordinates at time t for given ephemeris % eph % %SEARCH finds 'MaxCan' integer vectors whose distances to the real vector % 'a' are minimal in the metric of Q = transpose(L) D L. Only % integer vectors with a distance less than sqrt(Chic) are % regarded. % % The search for gridpoints inside the ambiguity search ellipsoid % is a sequential conditional adjustment upon the ambiguities. % The search starts by conditioning the last ambiguity a_n to an % integer, then a_{n-1} etc., until either % 1. the squared norm grows too large (out of the ellipsoid) % 2. an integer for a_1 is found: a full integer vector is % encountered (a gridpoint inside the ellipsoid) % If 1, the search goes back to some previous (towards a_n) % ambiguity and considers another integer. % %STORES Stores candidates and corresponding distances % %SUM_NORM Sums normals for double differenced GPS data % %TOGEOD Subroutine to calculate geodetic coordinates latitude, longitude, % height given Cartesian coordinates X,Y,Z, and reference ellipsoid % values semi-major axis a and the inverse of flattening finv. % The units of linear parameters X,Y,Z,a must all agree (m, km, mi, % ft, etc). The output units of angular quantities will be in % decimal degrees (15.5 degrees not 15 deg 30 min). The output % units of h will be the same as the units of X,Y,Z,a. % %TOPOCENT Transformation of vector dx into topocentric coordinate system % with origin at X. Both parameters are 3 by 1 vectors. % Output: D vector length in units like the input % Az azimuth from north positive clockwise, degrees % El elevation angle, degrees % %TROPO Calculation of tropospheric correction. The range correction % ddr in m is to be subtracted from pseudo-ranges and carrier % phases % sinel sin of elevation angle of satellite % hsta height of station in km % p atmospheric pressure in mb at height hp % tkel surface temperature in degrees Kelvin at height % htkel % hum humidity in % at height hhum % hp height of pressure measurement in km % htkel height of temperature measurement in km % hhum height of humidity measurement in km % Reference: Goad, C.C. & Goodman, L. (1974) A Modified % Tropospheric Refraction Correction Model. Paper presented at % the American Geophysical Union Annual Fall Meeting, San % Francisco, December 12-17 % %TROPP exhibits useful hints for handling graphics of axes, contour % labels and lines. We have chosen the tropospheric refraction % delay for demonstration. % %ZTRANSI Updates integral Z-transform for L; only column `first' until % `last'. The output is the inverse of Z transpose. %%%%%%%%%%%%%%%%% end contents.m %%%%%%%%%%%%%%%%%%%%