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May
2015
WorkHorse H-ADCP Operation Manual
Page 214
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
The H-ADCP packs velocity data for each depth cell of each beam into a two-byte, two’s-complement inte-
ger [-32768, 32767] with the LSB sent first. The H-ADCP scales velocity data in millimeters 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 setting of the EX-command (Coordinate Transformation) determines how the H-ADCP references the
velocity data as shown below.
EX-CMD
COORD SYS
VEL 1
VEL 2
VEL 3
VEL 4
EX00xxx
BEAM
TO BEAM 1
TO BEAM 2
TO BEAM 3
0
EX01xxx
INST
X AXIS
Y AXIS
0
ERROR VEL
EX10xxx
SHIP
X AXIS
Y AXIS
VERTICAL
ERROR VEL (tilt applied)
EX11xxx
EARTH
EAST
NORTH
VERTICAL
ERROR VEL (heading applied)
Positive values indicate water movement toward the H-ADCP.
Table 38:
Velocity Data Format
Hex Digit
Binary Byte
Field
Description
1-4
1,2
Velocity ID
Stores the velocity data identification word (00 01h).
5-8
3,4
Depth Cell 1, Veloci-
ty 1
Stores velocity data for depth cell #1, velocity 1. See above.
9-12
5,6
Depth Cell 1, Veloci-
ty 2
Stores velocity data for depth cell #1, velocity 2. See above.
13-16
7,8
Depth Cell 1, Veloci-
ty 3
Stores velocity data for depth cell #1, velocity 3. See above.
17-20
9,10
Depth Cell 1, Veloci-
ty 4
Stores velocity data for depth cell #1, velocity 4. See above.
21-2052
11-1026
Cells 2 – 128 (if used) These fields store the velocity data for depth cells 2 through 128 (depending on the
setting of the WN-command). These fields follow the same format as listed above for
depth cell 1.