iXBlue GAPS - Page 212

GAPS - User Guide
14
Bit 0 1 Reserved
Bits 3 to 1 3
Minor axe XY: small axe (in m) of the error ellipse representing the
standard deviation of the position in the XY plane
000: 0 m < standard deviation < 0,5 m
001: 0,5 m < standard deviation < 1,5 m
010: 1,5 m < standard deviation < 3 m
011: 3 m < standard deviation < 6 m
100: 6 m < standard deviation < 12 m
101: 12 m < standard deviation < 25 m
110: 25 m < standard deviation < 50 m
111: standard deviation > 50 m
Bits 7 to 4 4
Angle between the North
and the major axle of the
XY error ellipse l
180/2
4
0° 15/16x180°
15
Bit 0 1 Reserved
Bits 3 to 1 3
Standard deviation of the Z(m) position
000: 0 m < standard deviation < 0,5 m
001: 0,5 m < standard deviation < 1,5 m
010: 1,5 m < standard deviation < 3 m
011: 3 m < standard deviation < 6 m
100: 6 m < standard deviation < 12 m
101: 12 m < standard deviation < 25 m
110: 25 m < standard deviation < 50 m
111: standard deviation > 50 m
Bits 7 to 4 4 Reserved
16 PP
hex
8 Reserved
17, 18
19
rrrrrrrrrrrrrrrrrrrrrr
bin
(8+8+6 bits of:
- byte 17,
- byte 18,
- bits 5 to 0 of 19)
22
It is the truncation of the
absolute time procided by
the GPS to the USBL-BOX,
keeping only the minutes,
seconds, and milliseconds.
It is coded in milliseconds
number.
1 ms 0 ms
(3 599 999 ms,
i.e. 1h - 1ms
The largest
values of this
field do not
have any
meaning
Bits 7 and 6 of 19 2 Reserved
20 KK
hex
8 Status byte, Bits 0 to 8 - Reserved
21 SS
hex
8
Checksum
exclusive OR by byte for the whole 20 first bytes thus header included.
Immersion
definition
The immersion corresponds to the mobile depth with respect to the mean sea level (thus
heave corrected). This data is coherent with the one that would be given by a depth sensor on
the underwater mobile. But it does not allow to deduce the absolute position as there is no
compensation for tide.
212 MU-GAPS-AN-005-H - November 2019