include/predict/predict.h File Reference

#include <time.h>
#include <stdbool.h>

Include dependency graph for predict.h:

Go to the source code of this file.

Data Structures
struct	predict_tle_t
	Container for processed TLE data from TLE strings. More...
struct	predict_orbit_t
	Satellite orbit definitions, according to defined NORAD TLE. More...
struct	predict_observer_t
	Observation point/ground station (QTH). More...
struct	predict_observation
	Data relevant for a relative observation of an orbit or similar with respect to an observation point. More...
Defines
#define	PREDICT_VERSION_MAJOR   0
#define	PREDICT_VERSION_MINOR   1
#define	PREDICT_VERSION_PATCH   0
#define	PREDICT_VERSION   (PREDICT_VERSION_MAJOR * 100 * 100 + PREDICT_VERSION_MINOR * 100 + PREDICT_VERSION_PATCH)
#define	PREDICT_VERSION_STRING   "0.1.0"
Typedefs
typedef double	predict_julian_date_t
	The representation of time used by libpredict: The number of days since 31Dec79 00:00:00 UTC.
Enumerations
enum	predict_ephemeris { EPHEMERIS_SGP4 = 0, EPHEMERIS_SDP4 = 1, EPHEMERIS_SGP8 = 2, EPHEMERIS_SDP8 = 3 }
	Simplified perturbation models used in modeling the satellite orbits. More...
Functions
int	predict_version_major ()
	Get the major version number of the library.
int	predict_version_minor ()
	Get the minor version number of the library.
int	predict_version_patch ()
	Get the patch version number of the library.
int	predict_version ()
	Get the version number of the library.
char *	predict_version_string ()
	Get the version number string of the library.
predict_julian_date_t	predict_to_julian (time_t time)
	Convert time_t in UTC to Julian date in UTC.
time_t	predict_from_julian (predict_julian_date_t date)
	Convert Julian date in UTC back to a time_t in UTC.
predict_orbit_t *	predict_create_orbit (const char *tle[])
	Create orbit structure.
void	predict_destroy_orbit (predict_orbit_t *orbit)
	Free memory allocated in orbit structure.
int	predict_orbit (predict_orbit_t *x, predict_julian_date_t time)
	Main prediction function.
bool	predict_is_geostationary (const predict_orbit_t *x)
	Find whether orbit is geostationary.
double	predict_apogee (const predict_orbit_t *x)
	Get apogee of satellite orbit.
double	predict_perigee (const predict_orbit_t *x)
	Get perigee of satellite orbit.
bool	predict_aos_happens (const predict_orbit_t *x, double latitude)
	Find whether an AOS can ever happen on the given latitude.
bool	predict_decayed (const predict_orbit_t *x)
	Find whether an orbit has decayed.
bool	predict_is_eclipsed (const predict_orbit_t *x)
	Find whether a satellite is currently eclipsed.
double	predict_eclipse_depth (const predict_orbit_t *x)
	Return the eclipse depth.
predict_observer_t *	predict_create_observer (const char *name, double lat, double lon, double alt)
	Create observation point (QTH).
void	predict_destroy_observer (predict_observer_t *obs)
	Free observer.
void	predict_observe_orbit (const predict_observer_t *observer, const predict_orbit_t *orbit, struct predict_observation *obs)
	Find relative position of satellite with respect to an observer.
void	predict_observe_moon (const predict_observer_t *observer, predict_julian_date_t time, struct predict_observation *obs)
	Estimate relative position of the moon.
void	predict_observe_sun (const predict_observer_t *observer, predict_julian_date_t time, struct predict_observation *obs)
	Estimate relative position of the sun.
predict_julian_date_t	predict_next_aos (const predict_observer_t *observer, predict_orbit_t *orbit, predict_julian_date_t start_time)
	Find next acquisition of signal (AOS) of satellite (when the satellite rises above the horizon).
predict_julian_date_t	predict_next_los (const predict_observer_t *observer, predict_orbit_t *orbit, predict_julian_date_t start_time)
	Find next loss of signal (LOS) of satellite (when the satellite goes below the horizon).
double	predict_doppler_shift (const predict_observer_t *observer, const predict_orbit_t *orbit, double downlink_frequency)
	Calculate doppler shift of a given downlink frequency with respect to the observer.
double	predict_refraction (double el)
	Calculate refraction angle.
double	predict_refraction_ext (double el, double pressure, double temp)
	Calculate refraction angle.
double	predict_refraction_from_apparent (double apparent_el)
	Calculate refraction angle from apparent elevation.
double	predict_refraction_from_apparent_ext (double apparent_el, double pressure, double temp)
	Calculate refraction angle from apparent elevation.
double	predict_refraction_rate (double el, double el_rate)
	Calculate refraction rate of change.
double	predict_refraction_rate_ext (double el, double el_rate, double pressure, double temp)
	Calculate refraction rate of change.
double	predict_apparent_elevation (double el)
	Calculate apparent elevation from true elevation.
double	predict_apparent_elevation_ext (double el, double pressure, double temp)
	Calculate apparent elevation from true elevation.
double	predict_apparent_elevation_rate (double el, double el_rate)
	Calculate apparent elevation rate.
double	predict_apparent_elevation_rate_ext (double el, double el_rate, double pressure, double temp)
	Calculate apparent elevation rate.

---

Define Documentation

#define PREDICT_VERSION   (PREDICT_VERSION_MAJOR * 100 * 100 + PREDICT_VERSION_MINOR * 100 + PREDICT_VERSION_PATCH)

#define PREDICT_VERSION_MAJOR   0

#define PREDICT_VERSION_MINOR   1

#define PREDICT_VERSION_PATCH   0

#define PREDICT_VERSION_STRING   "0.1.0"

---

Typedef Documentation

typedef double predict_julian_date_t

The representation of time used by libpredict: The number of days since 31Dec79 00:00:00 UTC.

---

Enumeration Type Documentation

enum predict_ephemeris

Simplified perturbation models used in modeling the satellite orbits.

Enumerator:

EPHEMERIS_SGP4
EPHEMERIS_SDP4
EPHEMERIS_SGP8
EPHEMERIS_SDP8

---

Function Documentation

bool predict_aos_happens	(	const predict_orbit_t *	x,
		double	latitude
	)

Find whether an AOS can ever happen on the given latitude.

Parameters:

x	Satellite orbit
latitude	Latitude of ground station

Returns:

true if AOS can happen, otherwise false

Copyright:

GPLv2+

double predict_apogee

(

const predict_orbit_t *

x

)

Get apogee of satellite orbit.

Parameters:

x	Satellite orbit

Returns:

Apogee of orbit

Copyright:

GPLv2+

double predict_apparent_elevation

(

double

el

)

Calculate apparent elevation from true elevation.

Parameters:

el	True elevation angle (rad).

Returns:

Apparent elevation (rad).

double predict_apparent_elevation_ext	(	double	el,
		double	pressure,
		double	temp
	)

Calculate apparent elevation from true elevation.

Corrects for different atmospheric pressures and temperatures.

Parameters:

el	True elevation angle (rad).
pressure	Atmospheric pressure (kPa).
temp	Temperature (deg C).

Returns:

Apparent elevation (rad).

double predict_apparent_elevation_rate	(	double	el,
		double	el_rate
	)

Calculate apparent elevation rate.

Parameters:

el	True elevation angle (rad).
el_rate	Rate of change of true elevation angle (rad/s).

Returns:

Rate of change of apparent elevation (rad/s).

double predict_apparent_elevation_rate_ext	(	double	el,
		double	el_rate,
		double	pressure,
		double	temp
	)

Calculate apparent elevation rate.

Corrects for different atmospheric pressures and temperatures.

Parameters:

el	True elevation angle (rad).
el_rate	Rate of change of true elevation angle (rad/s).
pressure	Atmospheric pressure (kPa).
temp	Temperature (deg C).

Returns:

Rate of change of apparent elevation (rad/s).

predict_observer_t* predict_create_observer	(	const char *	name,
		double	lat,
		double	lon,
		double	alt
	)

Create observation point (QTH).

Parameters:

name	Name of observation point
lat	Latitude in radians (easting/northing)
lon	Longitude in radians (easting/northing)
alt	Altitude in meters

Returns:

Allocated observation point

predict_orbit_t* predict_create_orbit

(

const char *

tle[]

)

Create orbit structure.

Allocate memory and prepare internal data.

Parameters:

tle	NORAD two-line element set as string array

Returns:

Allocated orbit structure

Copyright:

GPLv2+

bool predict_decayed

(

const predict_orbit_t *

x

)

Find whether an orbit has decayed.

Parameters:

x	Current state of orbit

Returns:

true if orbit has decayed, otherwise false

Copyright:

GPLv2+

void predict_destroy_observer

(

predict_observer_t *

obs

)

Free observer.

Parameters:

obs	Observer to be freed.

void predict_destroy_orbit

(

predict_orbit_t *

orbit

)

Free memory allocated in orbit structure.

Parameters:

orbit

Orbit to free

double predict_doppler_shift	(	const predict_observer_t *	observer,
		const predict_orbit_t *	orbit,
		double	downlink_frequency
	)

Calculate doppler shift of a given downlink frequency with respect to the observer.

Parameters:

observer	Point of observation
orbit	Current state of satellite orbit
downlink_frequency	Downlink frequency of the satellite

Returns:

The frequency difference from the original frequency

Copyright:

GPLv2+

double predict_eclipse_depth

(

const predict_orbit_t *

x

)

Return the eclipse depth.

Parameters:

x	Current state of orbit

Returns:

Eclipse depth (rad)

time_t predict_from_julian

(

predict_julian_date_t

date

)

Convert Julian date in UTC back to a time_t in UTC.

Parameters:

date	Julian date in UTC

Returns:

Time in UTC

bool predict_is_eclipsed

(

const predict_orbit_t *

x

)

Find whether a satellite is currently eclipsed.

Parameters:

x	Current state of orbit

Returns:

true if orbit is eclipsed, otherwise false

bool predict_is_geostationary

(

const predict_orbit_t *

x

)

Find whether orbit is geostationary.

Parameters:

x	Satellite orbit

Returns:

true if orbit is geostationary, otherwise false

Copyright:

GPLv2+

predict_julian_date_t predict_next_aos	(	const predict_observer_t *	observer,
		predict_orbit_t *	orbit,
		predict_julian_date_t	start_time
	)

Find next acquisition of signal (AOS) of satellite (when the satellite rises above the horizon).

Ignores previous AOS of current pass if the satellite is in range at the start time.

Parameters:

observer	Point of observation
orbit	Satellite orbit
start_time	Start time for AOS search

Returns:

Time of AOS

Copyright:

GPLv2+

predict_julian_date_t predict_next_los	(	const predict_observer_t *	observer,
		predict_orbit_t *	orbit,
		predict_julian_date_t	start_time
	)

Find next loss of signal (LOS) of satellite (when the satellite goes below the horizon).

Finds LOS of the current pass if the satellite currently is in range, finds LOS of next pass if not.

Parameters:

observer	Point of observation
orbit	Satellite orbit
start_time	Start time for LOS search

Returns:

Time of LOS

Copyright:

GPLv2+

void predict_observe_moon	(	const predict_observer_t *	observer,
		predict_julian_date_t	time,
		struct predict_observation *	obs
	)

Estimate relative position of the moon.

Parameters:

observer	Point of observation
time	Time of observation
obs	Return object for position of the moon relative to the observer

Copyright:

GPLv2+

void predict_observe_orbit	(	const predict_observer_t *	observer,
		const predict_orbit_t *	orbit,
		struct predict_observation *	obs
	)

Find relative position of satellite with respect to an observer.

Calculates range, azimuth, elevation and relative velocity.

Parameters:

observer	Point of observation
orbit	Satellite orbit
obs	Return of object for position of the satellite relative to the observer.

Copyright:

GPLv2+

void predict_observe_sun	(	const predict_observer_t *	observer,
		predict_julian_date_t	time,
		struct predict_observation *	obs
	)

Estimate relative position of the sun.

Parameters:

observer	Point of observation
time	Time of observation
obs	Return object for position of the sun relative to the observer

Copyright:

GPLv2+

int predict_orbit	(	predict_orbit_t *	x,
		predict_julian_date_t	time
	)

Main prediction function.

Predict satellite orbit at given time.

Parameters:

x	Satellite orbit
time	Julian day in UTC

Returns:

0 if everything went fine

Copyright:

GPLv2+

double predict_perigee

(

const predict_orbit_t *

x

)

Get perigee of satellite orbit.

Parameters:

x	Satellite orbit

Returns:

Perigee of orbit

Copyright:

GPLv2+

double predict_refraction

(

double

el

)

Calculate refraction angle.

This function assumes atmospheric pressure of 101.0kPa and temperature 10deg celsius.

Parameters:

el	True elevation angle (rad).

Returns:

Refraction angle (rad).

double predict_refraction_ext	(	double	el,
		double	pressure,
		double	temp
	)

Calculate refraction angle.

Corrects for different atmospheric pressure and temperature.

Parameters:

el	True elevation angle in rads.
pressure	Atmospheric pressure in kPa.
temp	Temperature in deg celsius.

Returns:

Refraction angle (rad).

double predict_refraction_from_apparent

(

double

apparent_el

)

Calculate refraction angle from apparent elevation.

This function assumes atmospheric pressure of 101.0kPa and temperature 10deg celsius.

Parameters:

apparent_el

Apparent elevation angle (rad).

Returns:

Refraction angle (rad).

double predict_refraction_from_apparent_ext	(	double	apparent_el,
		double	pressure,
		double	temp
	)

Calculate refraction angle from apparent elevation.

Corrects for different atmospheric pressure and temperature.

Parameters:

apparent_el	Apparent elevation angle (rad).
pressure	Atmospheric pressure in kPa.
temp	Temperature in deg celsius.

Returns:

Refraction angle (rad).

double predict_refraction_rate	(	double	el,
		double	el_rate
	)

Calculate refraction rate of change.

Parameters:

el	True elevation angle (rad).
el_rate	Rate of change of true elevation angle (rad/s).

Returns:

Refraction rate of change (rad/s).

double predict_refraction_rate_ext	(	double	el,
		double	el_rate,
		double	pressure,
		double	temp
	)

Calculate refraction rate of change.

Corrects for different atmospheric pressure and temerature.

Parameters:

el	True elevation angle (rad).
el_rate	Rate of change of true elevation angle (rad/s).
pressure	Atmospheric pressure in kPa.
temp	Temperature in deg celsius.

Returns:

Apparent elevation (rad).

predict_julian_date_t predict_to_julian

(

time_t

time

)

Convert time_t in UTC to Julian date in UTC.

Parameters:

time	Time in UTC

Returns:

Julian day in UTC

int predict_version

(

)

Get the version number of the library.

Returns:

2 digit major, 2 digit minor, 2 digit patch decimal version number

int predict_version_major

(

)

Get the major version number of the library.

Returns:

Major version number

int predict_version_minor

(

)

Get the minor version number of the library.

Returns:

Minor version number

int predict_version_patch

(

)

Get the patch version number of the library.

Returns:

Patch version number

char* predict_version_string

(

)

Get the version number string of the library.

Returns:

Version number string ("major.minor.patch")