September
2017
Sentinel V SC and RT Operation Manual
Page 262
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
The Sentinel V ADCP packs velocity data for each depth cell of each beam into a two-byte, two’s-comple-
ment integer [-32768, 32767] with the LSB sent first. The Sentinel V ADCP scales velocity data in millime-
ters per second (mm/s). A value of –32768 (8000h) indicates bad velocity values.
All velocities are relative based on a stationary instrument. To obtain absolute velocities, algebraically re-
move the velocity of the instrument. For example,
RELATIVE WATER CURRENT VELOCITY: EAST 650 mm/s
INSTRUMENT VELOCITY : (-) EAST 600 mm/s
ABSOLUTE WATER VELOCITY : EAST 50 mm/s
The Coordinate Transformation determines how the Sentinel V ADCP references the velocity data as
shown below. The default coordinate system is beam.
EX-CMD COORD
SYS
VEL 1
VEL 2
VEL 3
VEL 4
EX00xxx BEAM
TO BEAM 1
TO BEAM 2
TO BEAM 3
TO BEAM 4
EX01xxx INSTRUME
NT
Bm1-Bm2
Bm4-Bm3
TO XDUCER
ERR VEL
EX10xxx SHIP
PRT-STBD
AFT-FWD
TO SURFACE
ERR VEL
EX11xxx EARTH
TO EAST
TO NORTH
TO SURFACE
ERR VEL
Positive values indicate water movement toward the ADCP.
Table 39:
Velocity Data Format
Binary
Byte
Field
Description
1,2
Velocity ID
Stores the velocity data identification word (00 01h).
3,4
Depth Cell 1,
Velocity 1
Stores velocity data for depth cell #1, velocity 1. See above.
5,6
Depth Cell 1,
Velocity 2
Stores velocity data for depth cell #1, velocity 2. See above.
7,8
Depth Cell 1,
Velocity 3
Stores velocity data for depth cell #1, velocity 3. See above.
9,10
Depth Cell 1,
Velocity 4
Stores velocity data for depth cell #1, velocity 4. See above.
11-max
Cells 2 – max
These fields store the velocity data for depth cells 2 through maximum (depending
on the setting of ReadyV). These fields follow the same format as listed above for
depth cell 1.
