flight/libraries/inc/WMMInternal.h

   1 /**
   2  ******************************************************************************
   3  *
   4  * @file       WMMInternal.h
   5  * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
   6  * @brief      Include file of the WorldMagModel internal functionality.
   7  *
   8  * @see        The GNU Public License (GPL) Version 3
   9  *
  10  *****************************************************************************/
  11 /*
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 3 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  19  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  20  * for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License along
  23  * with this program; if not, write to the Free Software Foundation, Inc.,
  24  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  25  */
  26
  27 #ifndef WMMINTERNAL_H_
  28 #define WMMINTERNAL_H_
  29 #include <pios_math.h>
  30
  31 // internal constants
  32 #define TRUE                                    ((uint16_t)1)
  33 #define FALSE                                   ((uint16_t)0)
  34 #define WMM_MAX_MODEL_DEGREES                   12
  35 #define WMM_MAX_SECULAR_VARIATION_MODEL_DEGREES 12
  36 #define NUMTERMS                                91             // ((WMM_MAX_MODEL_DEGREES+1)*(WMM_MAX_MODEL_DEGREES+2)/2);
  37 #define NUMPCUP                                 92              // NUMTERMS +1
  38 #define NUMPCUPS                                13             // WMM_MAX_MODEL_DEGREES +1
  39
  40 // internal structure definitions
  41 typedef struct {
  42     float EditionDate;
  43     float epoch; // Base time of Geomagnetic model epoch (yrs)
  44     char  ModelName[20];
  45 // float Main_Field_Coeff_G[NUMTERMS];  // C - Gauss coefficients of main geomagnetic model (nT)
  46 // float Main_Field_Coeff_H[NUMTERMS];  // C - Gauss coefficients of main geomagnetic model (nT)
  47 // float Secular_Var_Coeff_G[NUMTERMS]; // CD - Gauss coefficients of secular geomagnetic model (nT/yr)
  48 // float Secular_Var_Coeff_H[NUMTERMS]; // CD - Gauss coefficients of secular geomagnetic model (nT/yr)
  49     uint16_t nMax; // Maximum degree of spherical harmonic model
  50     uint16_t nMaxSecVar; // Maxumum degree of spherical harmonic secular model
  51     uint16_t SecularVariationUsed; // Whether or not the magnetic secular variation vector will be needed by program
  52 } WMMtype_MagneticModel;
  53
  54 typedef struct {
  55     float a; // semi-major axis of the ellipsoid
  56     float b; // semi-minor axis of the ellipsoid
  57     float fla; // flattening
  58     float epssq; // first eccentricity squared
  59     float eps; // first eccentricity
  60     float re; // mean radius of  ellipsoid
  61 } WMMtype_Ellipsoid;
  62
  63 typedef struct {
  64     float lambda; // longitude
  65     float phi; // geodetic latitude
  66     float HeightAboveEllipsoid; // height above the ellipsoid (HaE)
  67 } WMMtype_CoordGeodetic;
  68
  69 typedef struct {
  70     float lambda; // longitude
  71     float phig; // geocentric latitude
  72     float r; // distance from the center of the ellipsoid
  73 } WMMtype_CoordSpherical;
  74
  75 typedef struct {
  76     uint16_t Year;
  77     uint16_t Month;
  78     uint16_t Day;
  79     float    DecimalYear;
  80 } WMMtype_Date;
  81
  82 typedef struct {
  83     float Pcup[NUMPCUP]; // Legendre Function
  84     float dPcup[NUMPCUP]; // Derivative of Lagendre fn
  85 } WMMtype_LegendreFunction;
  86
  87 typedef struct {
  88     float Bx; // North
  89     float By; // East
  90     float Bz; // Down
  91 } WMMtype_MagneticResults;
  92
  93 typedef struct {
  94     float RelativeRadiusPower[WMM_MAX_MODEL_DEGREES + 1]; // [earth_reference_radius_km / sph. radius ]^n
  95     float cos_mlambda[WMM_MAX_MODEL_DEGREES + 1]; // cp(m)  - cosine of (m*spherical coord. longitude
  96     float sin_mlambda[WMM_MAX_MODEL_DEGREES + 1]; // sp(m)  - sine of (m*spherical coord. longitude)
  97 } WMMtype_SphericalHarmonicVariables;
  98
  99 typedef struct {
 100     float Decl; /* 1. Angle between the magnetic field vector and true north, positive east */
 101     float Incl; /*2. Angle between the magnetic field vector and the horizontal plane, positive down */
 102     float F; /*3. Magnetic Field Strength */
 103     float H; /*4. Horizontal Magnetic Field Strength */
 104     float X; /*5. Northern component of the magnetic field vector */
 105     float Y; /*6. Eastern component of the magnetic field vector */
 106     float Z; /*7. Downward component of the magnetic field vector */
 107     float GV; /*8. The Grid Variation */
 108     float Decldot; /*9. Yearly Rate of change in declination */
 109     float Incldot; /*10. Yearly Rate of change in inclination */
 110     float Fdot; /*11. Yearly rate of change in Magnetic field strength */
 111     float Hdot; /*12. Yearly rate of change in horizontal field strength */
 112     float Xdot; /*13. Yearly rate of change in the northern component */
 113     float Ydot; /*14. Yearly rate of change in the eastern component */
 114     float Zdot; /*15. Yearly rate of change in the downward component */
 115     float GVdot; /*16. Yearly rate of chnage in grid variation */
 116 } WMMtype_GeoMagneticElements;
 117
 118 // Internal Function Prototypes
 119 void WMM_Set_Coeff_Array();
 120 int WMM_GeodeticToSpherical(WMMtype_CoordGeodetic *CoordGeodetic, WMMtype_CoordSpherical *CoordSpherical);
 121 int WMM_DateToYear(uint16_t month, uint16_t day, uint16_t year);
 122 int WMM_Geomag(WMMtype_CoordSpherical *CoordSpherical,
 123                WMMtype_CoordGeodetic *CoordGeodetic, WMMtype_GeoMagneticElements *GeoMagneticElements);
 124
 125 int WMM_AssociatedLegendreFunction(WMMtype_CoordSpherical *CoordSpherical, uint16_t nMax, WMMtype_LegendreFunction *LegendreFunction);
 126
 127 int WMM_CalculateGeoMagneticElements(WMMtype_MagneticResults *MagneticResultsGeo, WMMtype_GeoMagneticElements *GeoMagneticElements);
 128
 129 int WMM_CalculateSecularVariation(WMMtype_MagneticResults *MagneticVariation, WMMtype_GeoMagneticElements *MagneticElements);
 130
 131 int WMM_ComputeSphericalHarmonicVariables(WMMtype_CoordSpherical *
 132                                           CoordSpherical, uint16_t nMax, WMMtype_SphericalHarmonicVariables *SphVariables);
 133
 134 int WMM_PcupLow(float *Pcup, float *dPcup, float x, uint16_t nMax);
 135
 136 int WMM_PcupHigh(float *Pcup, float *dPcup, float x, uint16_t nMax);
 137
 138 int WMM_RotateMagneticVector(WMMtype_CoordSpherical *,
 139                              WMMtype_CoordGeodetic *CoordGeodetic,
 140                              WMMtype_MagneticResults *MagneticResultsSph, WMMtype_MagneticResults *MagneticResultsGeo);
 141
 142 int WMM_SecVarSummation(WMMtype_LegendreFunction *LegendreFunction,
 143                         WMMtype_SphericalHarmonicVariables *
 144                         SphVariables, WMMtype_CoordSpherical *CoordSpherical, WMMtype_MagneticResults *MagneticResults);
 145
 146 int WMM_SecVarSummationSpecial(WMMtype_SphericalHarmonicVariables *
 147                                SphVariables, WMMtype_CoordSpherical *CoordSpherical, WMMtype_MagneticResults *MagneticResults);
 148
 149 int WMM_Summation(WMMtype_LegendreFunction *LegendreFunction,
 150                   WMMtype_SphericalHarmonicVariables *SphVariables,
 151                   WMMtype_CoordSpherical *CoordSpherical, WMMtype_MagneticResults *MagneticResults);
 152
 153 int WMM_SummationSpecial(WMMtype_SphericalHarmonicVariables *
 154                          SphVariables, WMMtype_CoordSpherical *CoordSpherical, WMMtype_MagneticResults *MagneticResults);
 155
 156 float WMM_get_main_field_coeff_g(uint16_t index);
 157 float WMM_get_main_field_coeff_h(uint16_t index);
 158 float WMM_get_secular_var_coeff_g(uint16_t index);
 159 float WMM_get_secular_var_coeff_h(uint16_t index);
 160
 161 #endif /* WMMINTERNAL_H_ */