1. PATCH TEST HYPACK ® MULTIBEAM COURSE
Pat asked to include USACE regs. for patch testing. I don’t see them here.

2. How is a Patch Test performed
ROLL: Flat / Smooth deep bottom
- Opposite / Reciprocal lines
- Same / Equal speeds
LATENCY: - Flat bottom to an object or
- Sloped bank feature
- Same direction lines
- Unequal speeds
PITCH: Flat bottom to an object or
- Sloped bank feature
- Opposite / Reciprocal lines
- Same / Equal speeds
Will be covered in detail at later session
Emphasize that Patch Test is a QC function … NOT a QA operation as is a Performance Test
Need be performed only periodically … equipment change. Not a daily event
Test question … does not correct Heave
YAW: Flat bottom to an object or
- Sloped bank feature
- Parallel offset lines that are
run in the Same direction
- Same / Equal speeds
4/15/2017
HYPACK® 2012 Training Seminar

3. HYPACK® 2012 Training Seminar
Patch Test Lines
Single Head
Latency: Line C D
Same line and direction
Differing speed, sloping bottom
(Watch for settlement differences.)
Pitch: Line C D
Reciprocal lines, sloping bottom. Same Survey speed.
Roll: Line A B
Reciprocal lines, flat bottom.
Same Survey speed.
Yaw: Lines C D, E F
Offset lines, sloping bottom.
Will be covered in detail at later session
Emphasize that Patch Test is a QC function … NOT a QA operation as is a Performance Test
Need be performed only periodically … equipment change. Not a daily event
Test question … does not correct Heave
4/15/2017
HYPACK® 2012 Training Seminar

4. HYPACK® 2012 Training Seminar
Finding Area to perform a Patch Test
This may be more difficult than it seems.
Try to find existing hydrographic charts
Locate the Flat area needed for the Roll Test
Locate the Sloped area for the Latency, Pitch, and Yaw Tests If known, locate an object (sunken boat or car, old bridge pier, rock pile, etc.) and use it.
Once you have located an area for your Patch Test, collect some data with your multibeam, over this area , in order that you can properly orient your Patch Test runlines with the bottom features needed. It won’t matter that your offsets are still zero, this is only for your runline setup.
4/15/2017
HYPACK® 2012 Training Seminar

5. HYPACK® 2012 Training Seminar
Patch Test Lines
Typical Slope ‘Shift’ feature for Yaw, Pitch, and Latency Runlines
Will be covered in detail at later session
Emphasize that Patch Test is a QC function … NOT a QA operation as is a Performance Test
Need be performed only periodically … equipment change. Not a daily event
Test question … does not correct Heave
4/15/2017
HYPACK® 2012 Training Seminar

6. Patch Test Lines Pitch Test
Because the Pitch Test runs lines in opposite directions,
a Squat issue may come into play, due to a strong current,
so be sure to extend each Runline well into the ‘Flat’ Area
This will allow you to verify whether a
‘vertical’ adjustment will need to be made
during the Pitch’s Patch Test
NOT compensating for this
‘vertical’ offset will cause
significant errors in the
Pitch Test values
Will be covered in detail at later session
Emphasize that Patch Test is a QC function … NOT a QA operation as is a Performance Test
Need be performed only periodically … equipment change. Not a daily event
Test question … does not correct Heave
Vertical Separation
4/15/2017
HYPACK® 2012 Training Seminar

7. HYPACK® 2012 Training Seminar
Patch Test Lines
If Possible, Find areas similar to these for Yaw, Pitch, and Latency Runlines
Will be covered in detail at later session
Emphasize that Patch Test is a QC function … NOT a QA operation as is a Performance Test
Need be performed only periodically … equipment change. Not a daily event
Test question … does not correct Heave
Two Slopes help to better define the Correction Value for the Test being performed
4/15/2017
HYPACK® 2012 Training Seminar

8. HYPACK® 2012 Training Seminar
Also keep in mind that your Boat Operator will make or BREAK your Patch Test.
The more precise that the Boat Operator can run the Patch Test
lines, the better the results will be.
Therefore, the Boat Operator should run the Latency, Pitch, and
Roll lines as close to Nadir beam over Nadir beam, from one pass
to the next.
4/15/2017
HYPACK® 2012 Training Seminar

9. HYPACK® 2012 Training Seminar
Yaw Lines
Yaw Runlines are meant to be Parallel to one another, however, in order to achieve 50% overlap throughout the entire Runline, the Boat Operator should follow the outside edge of the 1st Runline (As shown with the Yellow Line)
Will be covered in detail at later session
Emphasize that Patch Test is a QC function … NOT a QA operation as is a Performance Test
Need be performed only periodically … equipment change. Not a daily event
Test question … does not correct Heave
4/15/2017
HYPACK® 2012 Training Seminar

10. HYPACK® 2012 Training Seminar
Roll Area
Yaw Area
Get students to point out areas for each test, prior to putting the lines on the Map.
Latency & Pitch Area
4/15/2017
HYPACK® 2012 Training Seminar

11. HYPACK® 2012 Training Seminar
Patch Test Processing
In MBMAX
Load survey lines in pairs (the two pitch lines for example).
Edit through to Area Based Editing. Auto cell size in Matrix Setup usually works well.
Starting the Patch Test
The patch test works against a cross section cut through the survey lines.
Use Tools menu to Automatically cut a section or,
Use “Wrench” icon to Manually cut the section. (Preferred)
4/15/2017
HYPACK® 2012 Training Seminar

12. HYPACK® 2012 Training Seminar
“Manually” cut Cross Sections
Roll Test
Latency Test
Cut Perpendicular to Runline
Cut On Top of Trackline
Data Collection Direction
Pitch Test
Yaw Test
Cut Parallel to and Between the
Tracklines
4/15/2017
HYPACK® 2012 Training Seminar
Cut On Top of Trackline

13. How the Patch Test Works
Numerical Method
The cross sections are calculated at various angle offsets. For example; Pitch offset from -10 to 10 degrees in one degree steps.
An error value is calculated at each offset. Error = average depth difference between cross sections.
Minimum error is usually the correct offset. But not always.
Good Fit
Cross sections overlay well.
Error is at the minimum point.
Poor Fit
Cross sections overlay poorly.
Large error.
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14. HYPACK® 2012 Training Seminar
The Patch Test Window
Select Test
Pick the tab corresponding to the test you want to run.
Select Sonar Head
For dual head systems, select head 1 or 2
Results
Read test results here.
Error Graph
X axis is angle or time adjustment.
Y axis is the error; difference between cross sections.
Cross Sections
Red is the first line, Green is the second.
Vertical Adjustment
Moves the first line up or down if needed.
Override
Select Previous or Next adjustment.
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15. The New Patch Test Window
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16. HYPACK® 2012 Training Seminar
Patch Test Procedures
The order that you collect your Patch Test data
does NOT make any difference, but the order in which you process it, DOES…
Order of Processing:
Find the Latency offset first
Apply Latency, then do the Pitch test.
Apply Latency and Pitch, then do the Roll test.
Apply Latency, Pitch, and Roll, then finish with the Yaw test.
Also keep in mind that your Boat Operator will make or break your Patch Test. The more precise that the Boat Operator runs the Patch Test lines, the better the results will be.
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17. HYPACK® 2012 Training Seminar
Patch Test Procedures
Latency
Initial Time step of 0.1 second using DGPS for Latency test.
Decrease Step Increment while Increasing # of Steps for finer results.
(Suggested) Max. Resolution Max. Resolution
Step Increment # of Steps w/ DGPS w/ RTK GPS
Latency
Latency
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18. HYPACK® 2012 Training Seminar
Patch Test Procedures
Roll, Pitch, Yaw
Initial Angle Step of 1.0 degree using DGPS for Roll, Pitch and Yaw.
Decrease Step Increment while Increasing # of Steps for finer results.
(Suggested) Max. Resolution Max. Resolution
Step Increment # of Steps w/ DGPS w/ RTK GPS
Pitch, Yaw
Roll Pitch, Roll, Yaw
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19. HYPACK® 2012 Training Seminar
Patch Test Procedures
After running the data thru all four (4) Tests, then re-run
them all again.
This is done because you now have “rough” adjustments
for all four (4) offsets, and the Patch Test can now produce
“finer” results for each.
After this second run-thru, repeat for a Third time, but only
use the smallest two (2) Step Increments and their
respective # of Steps.
This will produce your “Best Results”.
Keep a record of all past Results, and use their Average 19
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20. HYPACK® 2012 Training Seminar
Roll Test
Single Head
Minimum Angle step of
0.1 degree
Good overlap in cross sections.
Good “V-Shaped” error curve. 20
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21. HYPACK® 2012 Training Seminar
Results
Some Error Curves
Good.
Bad. You should see a U-shaped error curve. This is the reasoning for the Increase # of Steps.
Test Results (from Patch Test window)
Adjustment: Patch test change to initial offset.
Initial Offset: Offset before patch test. From HYSWEEP® Hardware.
Final Offset: Offset after patch test. To be included in average for update to HYSWEEP® Hardware. 21
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HYPACK® 2012 Training Seminar 21