DR + GPS
STARTER KIT REFERENCE MANUAL
Lassen DR + GPS Reference Manual 87
Byte Name Type Units/LSB Range / Value Meaning
3-6 GPS Time of Week U32 1 ms 0-604800000
7-10 Latitude S32 2-31 sc [-½, ½] sc.
11-14 Longitude S32 2-31 sc [-1, 1) sc.
15-16 Altitude S16 1 m [-400,10000] m MSL
17-18 Heading U16 2-15 sc [0, 2) sc.
19-20 Speed U16 1 cm/s [0, 655.34] m/s
21-22 Delta time U16 1 ms [0, 1100] ms even
23-24 Delta Distance S16 1 cm [-327.67, 327.67] m
25-26 Delta Heading S16 1 cdeg [-327.67°, 327.67°]
27-28 Position accuracy U16 1 m [0, 65534] m
29-30 Altitude Accuracy U16 1 m [0, 65534] m
31-32 Heading Accuracy U16 2-15 sc [0, 2) sc.
33-34 Speed Accuracy U16 1 cm/s [0, 655.34] m/s
35-36 Delta distance accy U16 1 cm [0, 655.34] m
37-38 Delta heading accy U16 1 cdeg [0°, 360°]
39 0-6 # of Gyro Samples U7 0-127 < 110 typ
39 7 Direction Switch Value U1 1 = High
40-43 Gyro Counts U32 0-450560 Sum ADC values
44-45 Tacho Counts U16 0-65535 < 3300 typ
The data source of the fast fix can be inferred from the current tacho status, the
current gyro status, and the GPS age as follows:
Table 61: Fast Fix Data Sources
Tacho
Status Gyro
Status GPS
Age Lat / Lon
Source Altitude
Source Speed / Delta
Distance
Source
Heading /
Delta
Heading
Source
1 1 < 255 GPS + DR GPS DR + GPS Cal DR + GPS Cal
1 0 < 255 GPS + DR GPS DR + GPS Cal GPS
0 1 < 255 GPS GPS GPS DR + GPS Cal
0 0 < 255 GPS GPS GPS GPS
1 1 255 BBRAM + DR BBRAM DR DR
1 0 255 BBRAM BBRAM DR None
0 1 255 BBRAM BBRAM None DR
0 0 255 BBRAM BBRAM None None