Ryan Malloy
59fd8ba743
Extend od_observation_t with observer_idx so each observation can reference a different ground station. Config now holds an array of observers instead of a single pointer. The existing single-observer tle_from_topocentric() is unchanged (sets observer_idx=0 for all obs). New overload: tle_from_topocentric(topo[], ts[], observer[], int4[], ...) accepts parallel observer_ids array indexing into the observers array. PG function overloading resolves by argument types. Tests 9-11: two-station fit converges, single-station via multi-observer API matches, out-of-range observer_id raises error.
103 lines
3.0 KiB
C
103 lines
3.0 KiB
C
/*
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* od_solver.h -- TLE fitting via weighted least-squares differential correction
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*
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* Implements Vallado & Crawford (2008) AIAA 2008-6770:
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* - Equinoctial element perturbation
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* - SGP4 as the propagation engine
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* - Jacobian by finite differencing
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* - SVD solve via LAPACK dgelss_()
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* - Tiered step limiting (Vallado 2008 Section V.B)
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* - Brouwer-to-Kozai Newton-Raphson for TLE output
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*/
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#ifndef PG_ORRERY_OD_SOLVER_H
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#define PG_ORRERY_OD_SOLVER_H
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#include "norad.h"
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/* Maximum number of DC iterations */
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#define OD_MAX_ITER 25
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/* Convergence thresholds (Vallado 2008 Section V.A) */
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#define OD_RMS_REL_TOL 0.0002
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#define OD_RMS_ABS_TOL 0.0002
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/* Number of equinoctial states (6 orbital + optional B*) */
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#define OD_NSTATE_6 6
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#define OD_NSTATE_7 7
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/*
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* Observation type flag
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*/
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typedef enum
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{
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OD_OBS_ECI = 0, /* 6-component: x, y, z, vx, vy, vz (km, km/s) */
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OD_OBS_TOPO = 1 /* 3-component: az, el, range (rad, rad, km) */
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} od_obs_type_t;
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/*
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* Single observation for the DC solver
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*/
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typedef struct
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{
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double jd; /* Julian date of observation */
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double data[6]; /* ECI: [x,y,z,vx,vy,vz], topo: [az,el,range,...] */
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int observer_idx; /* index into config->observers[] (topo mode) */
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} od_observation_t;
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/*
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* Observer location (needed for topocentric mode)
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*/
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typedef struct
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{
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double lat; /* radians */
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double lon; /* radians */
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double alt_m; /* meters */
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double ecef[3]; /* pre-computed ECEF position (km) */
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} od_observer_t;
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/*
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* Solver configuration
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*/
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typedef struct
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{
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od_obs_type_t obs_type; /* ECI or topocentric */
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int fit_bstar; /* include B* as 7th state */
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int max_iter; /* iteration limit */
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od_observer_t *observers; /* array of observers (topo mode) */
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int n_observers; /* count (0 for ECI mode) */
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} od_config_t;
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/*
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* Solver result
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*/
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typedef struct
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{
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tle_t fitted_tle; /* resulting TLE (Kozai mean motion) */
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int iterations; /* iterations performed */
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double rms_initial; /* RMS residual before fitting (km) */
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double rms_final; /* RMS residual after fitting (km) */
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int converged; /* 1 if converged, 0 if hit max_iter */
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char status[64]; /* human-readable status */
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} od_result_t;
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/*
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* Primary entry point: fit a TLE from observations.
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*
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* obs: array of N observations
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* n_obs: number of observations (must be >= 6, or >= 7 if fit_bstar)
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* seed: initial TLE guess (if NULL, computed from first/last obs)
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* config: solver configuration
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* result: output (caller allocates)
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*
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* Returns 0 on success, -1 on error.
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*
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* Memory: all working arrays allocated via palloc() (when used from
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* PostgreSQL) or malloc() (standalone). Freed before return.
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*/
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int od_fit_tle(const od_observation_t *obs, int n_obs,
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const tle_t *seed, const od_config_t *config,
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od_result_t *result);
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#endif /* PG_ORRERY_OD_SOLVER_H */
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