Almanac

Classes
struct	almanac_t
Functions
void	calc_sat_az_el_almanac (almanac_t *alm, double t, s16 week, double ref[3], double *az, double *el)
double	calc_sat_doppler_almanac (almanac_t *alm, double t, s16 week, double ref[3])
void	calc_sat_state_almanac (almanac_t *alm, double t, s16 week, double pos[3], double vel[3])

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Detailed Description

Functions and calculations related to the GPS almanac.

Note:

All positions are referenced to the WGS84 coordinate system.

See also:

Coordinate systems

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Function Documentation

void calc_sat_az_el_almanac	(	almanac_t *	alm,
		double	t,
		s16	week,
		double	ref[3],
		double *	az,
		double *	el
	)

Calculate the azimuth and elevation of a satellite from a reference position given the satellite almanac.

Parameters:

alm	Pointer to an almanac structure for the satellite of interest.
t	GPS time of week at which to calculate the az/el.
week	GPS week number modulo 1024 or pass -1 to assume within one half-week of the almanac time of applicability.
ref	ECEF coordinates of the reference point from which the azimuth and elevation is to be determined, passed as [X, Y, Z], all in meters.
az	Pointer to where to store the calculated azimuth output.
el	Pointer to where to store the calculated elevation output.

Definition at line 130 of file almanac.c.

double calc_sat_doppler_almanac	(	almanac_t *	alm,
		double	t,
		s16	week,
		double	ref[3]
	)

Calculate the Doppler shift of a satellite as observed at a reference position given the satellite almanac.

Parameters:

alm	Pointer to an almanac structure for the satellite of interest.
t	GPS time of week at which to calculate the Doppler shift.
week	GPS week number modulo 1024 or pass -1 to assume within one half-week of the almanac time of applicability.
ref	ECEF coordinates of the reference point from which the azimuth and elevation is to be determined, passed as [X, Y, Z], all in meters.

Returns:

The Doppler shift in Hz.

Definition at line 150 of file almanac.c.

void calc_sat_state_almanac	(	almanac_t *	alm,
		double	t,
		s16	week,
		double	pos[3],
		double	vel[3]
	)

Calculate the position / velocity state of a satellite from the almanac.

Parameters:

alm	Pointer to an almanac structure for the satellite of interest.
t	GPS time of week at which to calculate the satellite state in seconds since Sunday.
week	GPS week number modulo 1024 or pass -1 to assume within one half-week of the almanac time of applicability.
pos	The satellite position in ECEF coordinates is returned in this vector.
vel	The satellite velocity in ECEF coordinates is returned in this vector. Ignored if NULL.

Definition at line 39 of file almanac.c.