Table 40: Echo Intensity Data Format - Teledyne WORKHORSE Operation Manual

May 2015
The echo intensity scale factor is about 0.45 dB per H-ADCP count. The H-ADCP does not directly check
for the validity of echo intensity data.
Table 40: Echo Intensity Data Format
Hex Digit Binary Byte
1 – 4 1,2
5,6 3
7,8 4
9,10 5
11,12 6
13 – 1028 7 – 514
The percent-good data field is a data-quality indicator that reports the percentage (0 to 100) of good data
collected for each depth cell of the velocity profile. The setting of the EX-command (Coordinate Trans-
formation) determines how the H-ADCP references percent-good data as shown below.
EX-Command Coordinate
System
xxx00xxx Beam
xxx01xxx Inst
xxx10xxx Ship
xxx11xxx Earth
1. Because profile data did not exceed correlation threshold (WC).
2. Because the error velocity threshold (WE) was exceeded.
At the start of the velocity profile, the backscatter echo strength is typically high on all three beams. Under
this condition, the H-ADCP uses all three beams to calculate the orthogonal and error velocities. As the
echo returns from far away depth cells, echo intensity decreases. At some point, the echo will be weak
enough on any given beam to cause the H-ADCP to reject some of its depth cell data. This causes the H-
ADCP to calculate velocities with two beams instead of three beams. When the H-ADCP does 2-beam so-
lutions, it stops calculating the error velocity because it needs three beams to do this. At some further
depth cell, the H-ADCP rejects all cell data because of the weak echo. As an example, let us assume depth
cell 60 has returned the following percent-good data.
FIELD #1 = 50, FIELD #2 = 5, FIELD #3 = 50, FIELD #4 = 0
The H-ADCP is very similar to the standard WorkHorse ADCP with four vertical beams. The
H-ADCP measures X and Y velocities on the Horizontal instead of X, Y, and Z on the Vertical. The
third beam on the H-ADCP provides the error velocity and acts in the same way as the fourth
beam on a vertical system.
If the EX-command was set to collect velocities in BEAM coordinates, the example values show the per-
centage of pings having good solutions in cell 60 for each beam based on the Low Correlation Threshold
(WC-command). Here, beam 1=50%, beam 2=5% and Beam 3=50%. These are neither typical nor desired
percentages. Typically, you would want all beams to be about equal and greater than 25%.
On the other hand, if velocities were collected in INSTRUMENT coordinates and bin 60 returned the fol-
lowing percent-good, the results would be interpreted differently.
Page 216
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
Field Description
ID Code Stores the echo intensity data identification word (00 03h).
Depth Cell 1, Field 1 Stores echo intensity data for depth cell #1, beam #1. See above.
Depth Cell 1, Field 2 Stores echo intensity data for depth cell #1, beam #2. See above.
Depth Cell 1, Field 3 Stores echo intensity data for depth cell #1, beam #3. See above.
RESERVED RESERVED
Cells 2 – 128 (if used) These fields store echo intensity data for depth cells 2 through 128 (depending on the
WN-command) for all three beams. These fields follow the same format as listed
above for depth cell 1.
Velocity 1
Percentage Of Good Pings For:
Beam 1
Field 1
Partial Solution Trans-
formation (note 1)
Velocity 2 Velocity 3
Beam 2 Beam 3
Percentage Of:
Field 2 Field 3
Transformations No Solution Available
Rejected (note 2) in Bin
WorkHorse H-ADCP Operation Manual
Velocity 4
RESERVED
Field 4
Full Solution Trans-
formations