GPS LNAV clock and ephemeris parameters in engineering units.
Each field holds the natural engineering-unit value, i.e. the product of the integer transmitted in the LNAV message and that parameter's IS-GPS-200 scale factor (the value listed in IS-GPS-200 Tables 20-I, 20-II, and 20-III). Angular ephemeris terms are in semicircles (1 semicircle = pi radians); multiply by pi to obtain radians. The harmonic correction terms are already in radians.
Subframe 1 - clock and health (IS-GPS-200 Table 20-I)
:week_number- GPS week number, 10-bit truncated (weeks, integer).:l2_code- code(s) on L2 indicator (2-bit code, integer; default 0).:l2_p_data_flag- L2-P data flag (0/1; default 0).:ura_index- SV accuracy (URA) index, 0..15 (integer).:sv_health- SV health, 6-bit (integer).:iodc- issue of data, clock, 10-bit (integer).:tgd- group delay differential (seconds).:toc- clock data reference time (seconds).:af0- SV clock bias (seconds).:af1- SV clock drift (seconds/second).:af2- SV clock drift rate (seconds/second^2).
Subframe 2 - ephemeris part 1 (IS-GPS-200 Table 20-II)
:iode- issue of data, ephemeris, 8-bit (integer).:crs- amplitude of the sine harmonic correction to orbit radius (meters).:delta_n- mean motion difference from computed value (semicircles/second).:m0- mean anomaly at reference time (semicircles).:cuc- amplitude of the cosine harmonic correction to argument of latitude (radians).:eccentricity- orbital eccentricity (dimensionless).:cus- amplitude of the sine harmonic correction to argument of latitude (radians).:sqrt_a- square root of the semi-major axis (sqrt(meters)).:toe- ephemeris reference time (seconds).:fit_interval_flag- fit-interval flag (0/1; default 0).:aodo- age of data offset term, 5-bit integer 0..31 (the offset in seconds is the term times 900; default 0).
Subframe 3 - ephemeris part 2 (IS-GPS-200 Table 20-III)
:cic- amplitude of the cosine harmonic correction to inclination (radians).:omega0- longitude of ascending node at weekly epoch (semicircles).:cis- amplitude of the sine harmonic correction to inclination (radians).:i0- inclination at reference time (semicircles).:crc- amplitude of the cosine harmonic correction to orbit radius (meters).:omega- argument of perigee (semicircles).:omega_dot- rate of right ascension (semicircles/second).:idot- rate of inclination angle (semicircles/second).
Summary
Types
@type t() :: %Sidereon.GNSS.Navigation.LNAV.Ephemeris{ af0: number(), af1: number(), af2: number(), aodo: non_neg_integer() | nil, cic: number(), cis: number(), crc: number(), crs: number(), cuc: number(), cus: number(), delta_n: number(), eccentricity: number(), fit_interval_flag: 0 | 1 | nil, i0: number(), idot: number(), iodc: non_neg_integer() | nil, iode: non_neg_integer(), l2_code: non_neg_integer() | nil, l2_p_data_flag: 0 | 1 | nil, m0: number(), omega: number(), omega0: number(), omega_dot: number(), sqrt_a: number(), sv_health: non_neg_integer(), tgd: number(), toc: number(), toe: number(), ura_index: non_neg_integer(), week_number: non_neg_integer() }
Functions
@spec example() :: t()
A representative set of clock and ephemeris parameters for a MEO GPS SV.
Useful for documentation and round-trip examples. Several signed fields carry negative values.