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Pathfinder DVL Guide April 2018
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
Page 183
Table 40: Bottom-Track Data Format
Hex Digit Binary
Byte
Field Description
21-24 11,12 BE/BT Err Vel Max Stores the error velocity maximum value ( BE - Error Velocity Maxi-
mum ).
Scaling: LSD = 1 mm/s; Range = 0 to 5000 mm/s (0 = did not screen
data)
25-32 13–16 Reserved Reserved
33-48 17-24 BT Range/Beam
#1-4 BT Range
Contains the two lower bytes of the vertical range from the Path-
finder to the sea bottom (or surface) as determined by each beam.
This vertical range does not consider the effects of pitch and roll.
When bottom detections are bad, BT Range = 0. See bytes 78
through 81 for MSB description and scaling.
Scaling: LSD = 1 cm; Range = 0 to 65535 cm
49-64 25-32 BT Velocity/Beam
#1-4 BT Vel
The meaning of the velocity depends on the coordinate system
command setting ( EX – Coordinate Transformation ).
For more information on coordinate transformations, see Beam Co-
ordinate Systems , page 29.
The four velocities are as follows:
a) Beam Coordinates: Beam 1, Beam 2, Beam 3, Beam 4
b) Instrument Coordinates: 1

2, 4

3, toward face, error
c) Ship Coordinates: Starboard, Fwd, Mast, Error
d) Earth Coordinates: East, North, Upward, Error
Scaling: LSD = 1 mm/s; Range = -10,000mm/s to +10,000mm/s
65-72 33-36 BTCM/Beam #1-4
BT Corr.
Contains the correlation magnitude in relation to the sea bottom
(or surface) as determined by each beam. Bottom-track correlation
magnitudes have the same format and scale factor as water-profil-
ing magnitudes.
73-80 37-40 BTEA/Beam #1-4
BT Eval Amp Contains the evaluation amplitude of the matching filter used in de-
termining the strength of the bottom echo.
Scaling: LSD = 1 count; Range = 0 to 255 counts
81-88 41-44
BTPG/Beam #1-4
BT %Good
Contains bottom-track percent-good data for each beam, which in-
dicate the reliability of bottom-track data. It is the percentage of
bottom-track pings that have passed the Pathfinder’s bottom-track
validity algorithm during an ensemble.
Scaling: LSD = 1 percent; Range = 0 to 100 percent
89-92
93-96 97
– 100
45,46
47,48
49,50
Ref Layer (Min,
Near, Far)
Stores the minimum layer size, the near boundary, and the far
boundary of the bottom track water-reference layer (
BL - Water-Mass
Layer Parameters
).
Scaling (minimum layer size): LSD = 1 dm; Range = 1-999 dm
Scaling (near/far boundaries): LSD = 1 dm; Range = 6-9999 dm
101- 116 51-58 Ref Vel/Beam
#1-4 Ref Layer Vel
Contains velocity data for the water mass for each beam. Water
mass velocities have the same format and scale factor as water-pro-
filing velocities (Table 35). The BL-command explains the water
mass.