This implements the World Magnetic Model providing the magnetic field vector, horizontal intensity, declination, inclination, and total intensity as outputs. This library is compatible with Arduino and CMake build systems.
Use the Arduino Library Manager to install this library or clone to your Arduino/libraries folder. Additionally, the Bolder Flight Systems Units library must be installed. This library is added as:
#include "wmm.h"An example Arduino executable is located at examples/arduino/wmm_ex/wmm_ex.ino. Teensy 3.x, 4.x, and LC devices are used for testing under Arduino and this library should be compatible with other devices.
CMake is used to build this library, which is exported as a library target called wmm. The header is added as:
#include "wmm.h"The library can be also be compiled stand-alone using the CMake idiom of creating a build directory and then, from within that directory issuing:
cmake ..
make
This will build the library and an example executable called wmm_ex. The example executable source file is located at examples/cmake/wmm_ex.cc.
This library is within the namespace bfs.
WmmData This struct is used to access the WMM outputs. The struct fields are:
- float mag_field_nt[3]: The magnetic field vector in the north, east, and down direction respectively. Units nT.
- float horz_intensity_nt: The horizontal intensity, returned as a scalar in nT.
- float declination_deg: Declination, returned as a scalar, in degrees (+ve east).
- float inclination_deg: Inclination, returned as a scalar, in degrees (+ve down).
- float total_intensity_nt: The total intensity, returned as a scalar in nT.
WmmModel This enum is used to optionally specify the model used. The options are:
- WMM2020: WMM2020 (epoch 2020–2025).
- WMM2015_V2: WMM2015v2 (epoch 2015–2020).
- WMM2015: WMM2015 (epoch 2015–2020). This version is not recommended. Use WMM2015V2 instead.
WmmData wrldmagm(const float alt, const float lat, const float lon, const float decyear, const WmmModel model, const AngPosUnit ang = AngPosUnit::DEG) Given the altitude above the WGS84 ellipsoid, the latitude, longitude, decimal year, and model, returns the WMM data in the WmmData structure format. Optionally, can specify the units for the latitude and longitude, the default is degrees.
bfs::WmmData data = bfs::wrldmagm(2062, 35.691544, -105.944183, 2022.5, bfs::WMM2015_V2);
std::cout << data.mag_field_nt[0] << std::endl;
std::cout << data.mag_field_nt[1] << std::endl;
std::cout << data.mag_field_nt[2] << std::endl;
std::cout << data.horz_intensity_nt << std::endl;
std::cout << data.declination_deg << std::endl;
std::cout << data.inclination_deg << std::endl;
std::cout << data.total_intensity_nt << std::endl;WmmData wrldmagm(const float alt, const float lat, const float lon, const float decyear, const WmmModel model, const AngPosUnit ang = AngPosUnit::DEG) Given the altitude above the WGS84 ellipsoid, the latitude, longitude, and decimal year, returns the WMM data in the WmmData structure format. Optionally, can specify the units for the latitude and longitude, the default is degrees. The WMM2020 model is used.
bfs::WmmData data = bfs::wrldmagm(2062, 35.691544, -105.944183, 2022.5);
std::cout << data.mag_field_nt[0] << std::endl;
std::cout << data.mag_field_nt[1] << std::endl;
std::cout << data.mag_field_nt[2] << std::endl;
std::cout << data.horz_intensity_nt << std::endl;
std::cout << data.declination_deg << std::endl;
std::cout << data.inclination_deg << std::endl;
std::cout << data.total_intensity_nt << std::endl;