190-00228-08
GPS 16x Technical Specifications
Rev. C
Page 24
alt
Ellipsoid altitude (meters)
epe
Estimated position error (meters)
eph
Position error, horizontal (meters)
epv
Position error, vertical (meters)
fix
0 = no fix; 1 = no fix; 2 = 2D; 3 = 3D; 4 = 2D differential; 5 = 3D differential;
6 and greater = not defined
gps_tow
GPS time of week (sec)
lat
Latitude (radians)
lon
Longitude (radians)
lon_vel
Longitude velocity (meters/second)
lat_vel
Latitude velocity (meters/second)
alt_vel
Altitude velocity (meters/ second)
msl_hght
height (mean sea level) (meters)
leap_sec
UTC leap seconds
grmn_days Garmin days (days since December 31, 1989)
Satellite Data Record
The satellite data has a record ID of 0x72 with 84 (0x54) data bytes. The data bytes contain data for 12 satellites as
described below.
typedef
struct
{
uint8
svid; //space vehicle identification (1–32 and 33–64 for WAAS)
uint16
snr; //signal-to-noise ratio
uint8
elev; //satellite elevation in degrees
uint16
azmth; //satellite azimuth in degrees
uint8
status; //status bit-field
} cpo_sat_data;
The status bit field represents a set of booleans described below:
Bit
Meaning when bit is one (1)
0
The unit has ephemeris data for the specified satellite.
1
The unit has a differential correction for the specified satellite.
2
The unit is using this satellite in the solution.
This pattern is repeated for 12 satellites for a total of 12 X 7 bytes = 84 (0x54) bytes.
The RS-232 Packet for the Satellite Record looks like:
- 0x10
(DLE is first byte)
- 0x72
(Record ID – single byte)
- 0x54
(Number of data bytes – single byte)
- 12 cpo_sat_data records
- 0x##
(2’s complement of the arithmetic sum of the bytes between the delimiters)
- 0x10
(DLE)
- 0x03
(ETX is last byte)
The USB Packet for the Satellite Record looks like:
- 0x72
(Record ID – single byte)
- 0x54
(Number of data bytes – single byte)
- 12 cpo_sat_data records