SEM_structAlmanac Struct Reference

#include <sem.h>


Detailed Description

A limited set of satellite orbit parameters that is used to calculate GPS satellite positions and velocities. In the ephemeris structure below, the parameters for computing satellite clock corrections are also included.

Author:
Glenn D. MacGougan (GDM)
Date:
2006-11-10
Since:
2005-08-15
Remarks:
(1) Struct packaging: compatible with 4 and 8 byte packing
(2) The af0 and af1 parameters are typically from low precision sources like the true broadcast GPS almanacs. The af0 and af1 parameters are preferred from ephemeris download as they have higher precision.
REFERENCES
[1] http://www.navcen.uscg.gov/gps/almanacs.htm

Definition at line 65 of file sem.h.


Data Fields

unsigned toa
 almanac time of applicability (reference time) [s]
unsigned short week
 10 bit gps week 0-1023 (user must account for week rollover) [week]
unsigned short prn
 GPS prn number [].
unsigned short reserved
 reserved
unsigned short svn
 Satellite vehicle number [].
unsigned char ura
 User Range Accuracy lookup code, [0-15], see p. 83 GPSICD200C, 0 is excellent, 15 is use at own risk.
unsigned char health
 0=healthy, unhealthy otherwise [], subframe 4 and 5, page 25 six-bit health code
unsigned char config_code
 configuration code [], if >=9 Anti-Spoofing is on
unsigned char is_af0_af1_high_precision
 indicates precision of af0 and af1 [1=high precision,0=low precision] (22&16 bits, ephemeris source) vs (11&11 bits, almanac source), 0 is typical for most SEM sources
double ecc
 eccentricity []
double i0
 orbital inclination at reference time [rad]
double omegadot
 rate of right ascension [rad/s]
double sqrta
 square root of the semi-major axis [m^(1/2)]
double omega0
 longitude of ascending node of orbit plane at weekly epoch [rad]
double w
 argument of perigee [rad]
double m0
 mean anomaly at reference time [rad]
double af0
 polynomial clock correction coefficient (clock bias) [s], Note: parameters from ephemeris preferred vs almanac (22 vs 11 bits)
double af1
 polynomial clock correction coefficient (clock drift) [s/s], Note: parameters from ephemeris preferred vs almanac (16 vs 11 bits)

Field Documentation

unsigned SEM_structAlmanac::toa

almanac time of applicability (reference time) [s]

Definition at line 67 of file sem.h.

unsigned short SEM_structAlmanac::week

10 bit gps week 0-1023 (user must account for week rollover) [week]

Definition at line 68 of file sem.h.

unsigned short SEM_structAlmanac::prn

GPS prn number [].

Definition at line 69 of file sem.h.

unsigned short SEM_structAlmanac::reserved

reserved

Definition at line 70 of file sem.h.

unsigned short SEM_structAlmanac::svn

Satellite vehicle number [].

Definition at line 71 of file sem.h.

unsigned char SEM_structAlmanac::ura

User Range Accuracy lookup code, [0-15], see p. 83 GPSICD200C, 0 is excellent, 15 is use at own risk.

Definition at line 72 of file sem.h.

unsigned char SEM_structAlmanac::health

0=healthy, unhealthy otherwise [], subframe 4 and 5, page 25 six-bit health code

Definition at line 73 of file sem.h.

unsigned char SEM_structAlmanac::config_code

configuration code [], if >=9 Anti-Spoofing is on

Definition at line 74 of file sem.h.

unsigned char SEM_structAlmanac::is_af0_af1_high_precision

indicates precision of af0 and af1 [1=high precision,0=low precision] (22&16 bits, ephemeris source) vs (11&11 bits, almanac source), 0 is typical for most SEM sources

Definition at line 77 of file sem.h.

double SEM_structAlmanac::ecc

eccentricity []

Definition at line 79 of file sem.h.

double SEM_structAlmanac::i0

orbital inclination at reference time [rad]

Definition at line 80 of file sem.h.

double SEM_structAlmanac::omegadot

rate of right ascension [rad/s]

Definition at line 81 of file sem.h.

double SEM_structAlmanac::sqrta

square root of the semi-major axis [m^(1/2)]

Definition at line 82 of file sem.h.

double SEM_structAlmanac::omega0

longitude of ascending node of orbit plane at weekly epoch [rad]

Definition at line 83 of file sem.h.

double SEM_structAlmanac::w

argument of perigee [rad]

Definition at line 84 of file sem.h.

double SEM_structAlmanac::m0

mean anomaly at reference time [rad]

Definition at line 85 of file sem.h.

double SEM_structAlmanac::af0

polynomial clock correction coefficient (clock bias) [s], Note: parameters from ephemeris preferred vs almanac (22 vs 11 bits)

Definition at line 86 of file sem.h.

double SEM_structAlmanac::af1

polynomial clock correction coefficient (clock drift) [s/s], Note: parameters from ephemeris preferred vs almanac (16 vs 11 bits)

Definition at line 87 of file sem.h.


The documentation for this struct was generated from the following file: