matlab.zip_Matlab 航天_aerospace matlab_matlab_matlab 软件_航天

% ----------------------------------------------------------------------------- % % procedure sgp4init % % this procedure initializes variables for sgp4. % % Author: % Jeff Beck % beckja@alumni.lehigh.edu % 1.0 (aug 7, 2006) - update for paper dav % original comments from Vallado C++ version: % author : david vallado 719-573-2600 28 jun 2005 % % inputs : % satn - satellite number % bstar - sgp4 type drag coefficient kg/m2er % ecco - eccentricity % epoch - epoch time in days from jan 0, 1950. 0 hr % argpo - argument of perigee (output if ds) % inclo - inclination % mo - mean anomaly (output if ds) % no - mean motion % nodeo - right ascension of ascending node % % outputs : % satrec - common values for subsequent calls % return code - non-zero on error. % 1 - mean elements, ecc >= 1.0 or ecc < -0.001 or a < 0.95 er % 2 - mean motion less than 0.0 % 3 - pert elements, ecc < 0.0 or ecc > 1.0 % 4 - semi-latus rectum < 0.0 % 5 - epoch elements are sub-orbital % 6 - satellite has decayed % % locals : % CNODM , SNODM , COSIM , SINIM , COSOMM , SINOMM % Cc1sq , Cc2 , Cc3 % Coef , Coef1 % cosio4 - % day - % dndt - % em - eccentricity % emsq - eccentricity squared % eeta - % etasq - % gam - % argpm - argument of perigee % ndem - % inclm - inclination % mm - mean anomaly % nm - mean motion % perige - perigee % pinvsq - % psisq - % qzms24 - % rtemsq - % s1, s2, s3, s4, s5, s6, s7 - % sfour - % ss1, ss2, ss3, ss4, ss5, ss6, ss7 - % sz1, sz2, sz3 % sz11, sz12, sz13, sz21, sz22, sz23, sz31, sz32, sz33 - % tc - % temp - % temp1, temp2, temp3 - % tsi - % xpidot - % xhdot1 - % z1, z2, z3 - % z11, z12, z13, z21, z22, z23, z31, z32, z33 - % % coupling : % getgravconst % initl - % dscom - % dpper - % dsinit - % sgp4 - % % references : % hoots, roehrich, norad spacetrack report #3 1980 % hoots, norad spacetrack report #6 1986 % hoots, schumacher and glover 2004 % vallado, crawford, hujsak, kelso 2006 % ----------------------------------------------------------------------------*/ function [satrec] = sgp4init(whichconst, satrec, xbstar, xecco, epoch, ... xargpo, xinclo, xmo, xno, xnodeo); % /* ------------------------ initialization --------------------- */ % /* ----------- set all near earth variables to zero ------------ */ satrec.isimp = 0; satrec.method = 'n'; satrec.aycof = 0.0; satrec.con41 = 0.0; satrec.cc1 = 0.0; satrec.cc4 = 0.0; satrec.cc5 = 0.0; satrec.d2 = 0.0; satrec.d3 = 0.0; satrec.d4 = 0.0; satrec.delmo = 0.0; satrec.eta = 0.0; satrec.argpdot = 0.0; satrec.omgcof = 0.0; satrec.sinmao = 0.0; satrec.t = 0.0; satrec.t2cof = 0.0; satrec.t3cof = 0.0; satrec.t4cof = 0.0; satrec.t5cof = 0.0; satrec.x1mth2 = 0.0; satrec.x7thm1 = 0.0; satrec.mdot = 0.0; satrec.nodedot = 0.0; satrec.xlcof = 0.0; satrec.xmcof = 0.0; satrec.nodecf = 0.0; % /* ----------- set all deep space variables to zero ------------ */ satrec.irez = 0; satrec.d2201 = 0.0; satrec.d2211 = 0.0; satrec.d3210 = 0.0; satrec.d3222 = 0.0; satrec.d4410 = 0.0; satrec.d4422 = 0.0; satrec.d5220 = 0.0; satrec.d5232 = 0.0; satrec.d5421 = 0.0; satrec.d5433 = 0.0; satrec.dedt = 0.0; satrec.del1 = 0.0; satrec.del2 = 0.0; satrec.del3 = 0.0; satrec.didt = 0.0; satrec.dmdt = 0.0; satrec.dnodt = 0.0; satrec.domdt = 0.0; satrec.e3 = 0.0; satrec.ee2 = 0.0; satrec.peo = 0.0; satrec.pgho = 0.0; satrec.pho = 0.0; satrec.pinco = 0.0; satrec.plo = 0.0; satrec.se2 = 0.0; satrec.se3 = 0.0; satrec.sgh2 = 0.0; satrec.sgh3 = 0.0; satrec.sgh4 = 0.0; satrec.sh2 = 0.0; satrec.sh3 = 0.0; satrec.si2 = 0.0; satrec.si3 = 0.0; satrec.sl2 = 0.0; satrec.sl3 = 0.0; satrec.sl4 = 0.0; satrec.gsto = 0.0; satrec.xfact = 0.0; satrec.xgh2 = 0.0; satrec.xgh3 = 0.0; satrec.xgh4 = 0.0; satrec.xh2 = 0.0; satrec.xh3 = 0.0; satrec.xi2 = 0.0; satrec.xi3 = 0.0; satrec.xl2 = 0.0; satrec.xl3 = 0.0; satrec.xl4 = 0.0; satrec.xlamo = 0.0; satrec.zmol = 0.0; satrec.zmos = 0.0; satrec.atime = 0.0; satrec.xli = 0.0; satrec.xni = 0.0; % sgp4fix - note the following variables are also passed directly via satrec. % it is possible to streamline the sgp4init call by deleting the "x" % variables, but the user would need to set the satrec.* values first. we % include the additional assignment in case twoline2rv is not used. satrec.bstar = xbstar; satrec.ecco = xecco; satrec.argpo = xargpo; satrec.inclo = xinclo; satrec.mo = xmo; satrec.no = xno; satrec.nodeo = xnodeo; % /* -------------------- wgs-72 earth constants ----------------- */ % // sgp4fix identify constants and allow alternate values global tumin mu radiusearthkm xke j2 j3 j4 j3oj2 [tumin, mu, radiusearthkm, xke, j2, j3, j4, j3oj2] = getgravc( whichconst ); ss = 78.0 / radiusearthkm + 1.0; qzms2t = ((120.0 - 78.0) / radiusearthkm)^4; x2o3 = 2.0 / 3.0; % sgp4fix divisor for divide by zero check on inclination % the old check used 1.0 + cos(pi-1.0e-9), but then compared it to % 1.5 e-12, so the threshold was changed to 1.5e-12 for consistancy temp4 = 1.5e-12; satrec.init = 'y'; satrec.t = 0.0; [ainv, ao, satrec.con41, con42, cosio, cosio2, einv, eccsq,... satrec.method, omeosq, posq, rp, rteosq, sinio,... satrec.gsto, satrec.no]... = initl(... satrec.ecco, epoch, satrec.inclo, satrec.no,... satrec.satnum); satrec.error = 0; if (rp < 1.0) % printf("# *** satn%d epoch elts sub-orbital ***\n", satn); satrec.error = 5; end if ((omeosq >= 0.0 ) | ( satrec.no >= 0.0)) satrec.isimp = 0; if (rp < (220.0 / radiusearthkm + 1.0)) satrec.isimp = 1; end sfour = ss; qzms24 = qzms2t; perige = (rp - 1.0) * radiusearthkm; % /* - for perigees below 156 km, s and qoms2t are altered - */ if (perige < 156.0) sfour = perige - 78.0; if (perige < 98.0) sfour = 20.0; end qzms24 = ((120.0 - sfour) / radiusearthkm)^4.0; sfour = sfour / radiusearthkm + 1.0; end pinvsq = 1.0 / posq; tsi = 1.0 / (ao - sfour); satrec.eta = ao * satrec.ecco * tsi; etasq = satrec.eta * satrec.eta; eeta = satrec.ecco * satrec.eta; psisq = abs(1.0 - etasq); coef = qzms24 * tsi^4.0; coef1 = coef / psisq^3.5; cc2 = coef1 * satrec.no * (ao * (1.0 + 1.5 * etasq + eeta *... (4.0 + etasq)) + 0.375 * j2 * tsi / psisq * satrec.con41 *... (8.0 + 3.0 * etasq * (8.0 + etasq))); satrec.cc1 = satrec.bstar * cc2; cc3 = 0.0; if (satrec.ecco > 1.0e-4) cc3 = -2.0 * coef * tsi * j3oj2 * satrec.no * sinio / satrec.ecco; end satrec.x1mth2 = 1.0 - cosio2;