The MAZOOPS Project
Third year of engineering school internship report
MPL supervisor: Dr. Jules S. Jaffe
ISITV supervisor: Dr. Marc Francius
Student:
Florian Aulanier
Third year of engineering school report – Florian Aulanier
1 Acknowledgment
This internship has been for me a very good experience on the scientific and technical aspects
of developing underwater imaging systems. It was a real pleasure for me to spend six months
collaborating with the members of Dr. Jules Jaffe’s Group.
That is why I am particularly grateful to Dr. Jules Jaffe who has offered me the opportunity to
work in his group on the Multiple Angle Zooplankton Sonar and who has supervised this
internship in organizing group meetings and in being available.
I would like to thank Dr. Francius and Dr. Fraunié for having been my tutor from respectively
the ISITV and the USTV and for their availability.
I give thanks to Fernando Simonet for his patience, his precious help during all the internship
and for having made easy my integration in the group.
I thank Paul Roberts who has helped me to understand his work; who has been available each
time I needed help or advice and I thank him also for helping me to find housing and for
having interesting discussions.
I would like to thank Prasana Shevade with who I have enjoyed collaborating and sharing
experiences.
Thanks to Lauren Shwisberg who helped me to set and perform the experiments in the OASIS
Lab.
Thanks to Kevin Lu for having shown me his work and having share experiences.
I would like to thank Evelyn Doudera and Norissa Gastelum for having helped me for
administrative tasks and acquiring hardware.
Un grand merci à Julien Lenoob pour m’avoir appris le fonctionnement d’un oscilloscope
numérique et poussé à donner le meilleur de moi même dans une lutte psychologique
acharnée et pleine de rebondissements.
I would like to thank Alexander Gershunov and Benjamin Maurer for their psychological
support, their wise advices and the interesting discussions we have had.
Finally, I would give thanks to all the people I met during this internship who have made me
have a good time.
Florian Aulanier.
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Third year of engineering school report – Florian Aulanier
1
ACKNOWLEDGMENT ............................................................................................................................. 1
2
INTRODUCTION ....................................................................................................................................... 3
3
INSTITUTION, LABORATORY AND GROUP PRESENTATION..................................................... 4
3.1
3.2
4
SCRIPPS INSTITUTION OF OCEANOGRAPHY AND THE MARINE PHYSICAL LABORATORY (MPL) ........... 4
JAFFE LABORATORY FOR UNDERWATER IMAGING ............................................................................... 5
MAZOOPS SYSTEM.................................................................................................................................. 6
4.1
GENERAL DESCRIPTION......................................................................................................................... 6
4.2
MECHANICAL STRUCTURE .................................................................................................................... 7
4.2.1
Towed Fish ...................................................................................................................................... 7
4.2.2
Main Housing.................................................................................................................................. 8
4.2.3
Hydrophone housings...................................................................................................................... 8
4.2.4
Camera housings............................................................................................................................. 9
4.2.5
Clamps ............................................................................................................................................ 9
4.3
ELECTRONIC COMPONENTS ................................................................................................................. 10
4.3.1
Acoustics Part ............................................................................................................................... 10
4.3.2
Video Part ..................................................................................................................................... 14
4.3.3
Communication Part ..................................................................................................................... 16
4.4
SOFTWARE PART ................................................................................................................................ 16
4.4.1
General functioning....................................................................................................................... 16
4.4.2
Data acquisition (DAQ) ................................................................................................................ 17
4.4.3
Function generation ...................................................................................................................... 19
4.4.4
Camera.......................................................................................................................................... 20
4.4.5
Synchronization and counter outputs ............................................................................................ 21
4.4.6
Raw Data Display ......................................................................................................................... 22
4.4.7
Data Saving................................................................................................................................... 22
4.4.8
Light Dimming .............................................................................................................................. 23
4.4.9
Switches......................................................................................................................................... 23
4.4.10
Front Panel............................................................................................................................... 24
5
INTERNSHIP DEVELOPMENT ............................................................................................................ 26
5.1
5.1.1
5.1.2
5.1.3
5.2
5.3
5.4
5.4.1
5.4.2
6
BACKGROUND .................................................................................................................................... 26
Goal............................................................................................................................................... 26
Zooplankton................................................................................................................................... 26
Sonar equation .............................................................................................................................. 27
GETTING IN TOUCH WITH THE MAZOOPS PROJECT ........................................................................... 28
SONAR DEVELOPMENT ........................................................................................................................ 29
EXPERIMENT ....................................................................................................................................... 30
Experimental set up....................................................................................................................... 30
Data Processing ............................................................................................................................ 32
CONCLUSIONS........................................................................................................................................ 33
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Third year of engineering school report – Florian Aulanier
2 Introduction
Involved in a master’s degree in marine engineering and subsea technologies at the Institute
of Engineering Sciences of Toulon and the Var (ISITV) and in a master’s degree in physical
oceanography, signal processing and remote sensing at the University of the South ToulonVar ; I have had the chance to work in the Dr. Jules’ Jaffe Group, Marine Physical
Laboratory, Scripps Institution of Oceanography, University of California San Diego during a
6 months internship.
The goal of this internship was to develop and build a new sonar system designed to classify
zooplankton with acoustic signals. This project is a technical and scientific realization which
aims to participate in the study of marine ecosystem. Technical and engineering skills but also
competences in signal processing, remote sensing and biology are needed to carry out this
kind of projects. It implies the collaboration of people with very different backgrounds and
makes it very interesting.
To report this experience I will present in a first part the Dr. Jaffe’s group, its different
projects as well as the Marine Physical Laboratory and the Scripps Institution of
Oceanography. Then, in a second part, I will describe in detail the Multiple Angle
Zooplankton Sonar (MAZOOPS) and start the documentation about the MAZOOPS system.
In a third part, I will explain the MAZOOPS project to finally conclude about this experience
in the last part.
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3 Institution, Laboratory and Group presentation
3.1 Scripps Institution of Oceanography and the Marine Physical
Laboratory (MPL)
The Scripps Institution of Oceanography (SIO) was founded in 1903 in San Diego, mainly by
Professor William Ritter, E. W. Scripps and Ellen Browning Scripps. At the beginning the
institution was the Marine Biological Association. It is only in 1925 that the institution got the
name of Scripps Institution of Oceanography while it expanded to study other fields of
oceanography.
Today, Scripps staff numbers
approximately 1,300, including about
100 faculty, more than 300 other
scientists, and some 240 graduate
students. There are librarians,
technicians, ship crews, various
specialists, and visitors from many
nations involved in research and
educational programs.
Figure 1: Scripps Pier.
Figure 2: Aerial view of Scripps Institution of Oceanography.
The Marine Physical Laboratory
(MPL) is an organized research unit
of the University of California, San
Diego and an integral part of the
academic environment of the Scripps
Institution of Oceanography.
Originally established as a Navyorientated research laboratory in
1946, MPL has maintained a strong
multidisciplinary research program
consisting entirely of sponsored projects, with a large
sponsorship from the Department of Defense (DOD), the
National Science Foundation (NSF) and the Office of
Naval Research (ONF).
Exploratory and technology-based research and
development are conducted at the Laboratory, with a focus
on unique underwater sensor systems designed to meet
specific research goals.
Figure 3: Spiess Hall.
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3.2 Jaffe Laboratory for Underwater Imaging
The Jaffe Laboratory for Underwater Imaging is a part of the MPL which aims to research
and develop optical and acoustical instruments and methods to study the marine environment.
Fish TV, a three dimensional
sonar imaging system and the
Autonomous Underwater
Explorers (AUE), are two
examples of the previous
realizations carried through by
the Jaffe Laboratory for
Underwater Imaging which can
be seen in detail at
http://jaffeweb.ucsd.edu/
Figure 4: On
amongst others.
the left, AUEs
on the right
Fish TV.
The team is compounded by:
Jules S. Jaffe, Research Oceanographer, principal investigator
Fernando Simonet, Associate Engineer
Robert Glatts, Associate Engineer
Paul L. Roberts, Post doc.
Justin Haag, PhD student
Prasana Shevade, undergraduate student.
Kevin Liu, undergraduate student.
Lauren Schwartz, summer intern 2009
Nick Cavanaugh, summer intern 2009.
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4 MAZOOPS System
4.1 General description
The MAZOOPS system is a multiangle sonar designed to classify zooplankton using acoustic
waves. It will be used by scientists to estimate abundance of several taxa of zooplankton
during cruises on scientific research vessels. The requirements for such a system are
summarized in the APTE diagram here under completed by the Figure 5 page 4.
Figure 5: APTE diagram of the MAZOOPS System. PF = Principal Function, CF = Constraint Function.
Two versions of MAZOOPS will be made. A towed one and sea bed one on the picture
bellow.
Figure 6: On the left, the towed system ready to be tested underwater. On the right, a scheme of the future
sea bed system.
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Each system consists of a mechanical structure, and electronic hardware and software.
For both systems, the electronic hardware and software are identical.
However, the mechanical structure is quite different and only the one of them, the towed
system, will be studied in detail in the following report.
Main characteristics of the towed system:
Data Acquisition Rate: 10MS/s.
Data Acquisition Resolution: 12 bits.
Transmission Maximum Sampling Rate: 100 MS/s.
Transmission Resolution: 14 bits.
Maximum Ping Emission Rate: About 3 Hz.
Maximum Transmission: 250Vpp at 10 pings/s, equivalent to 223 dB ref µPa at 1m.
Emission Sensitivity: 184dB ±3dB at 2 Mhz (re µPa/V at 1m).
Reception Sensitivity: -207 dB ±3 dB at 2 MHz (re V/µPa).
Sounding Range: 1m.
Depth: 500m.
Total Air Weight: About 100kg.
Total Water Weight:
Autonomy: 6 hours.
Recharge: 16 hours.
4.2 Mechanical Structure
The goal of this structure is to make the MAZOOPS system towable by a boat. The structure
will also link the different part of the system. More important this structure permits to align
very precisely hydrophones and camera on the same field of view.
4.2.1 Towed Fish
The main part of the structure is a “fish” formerly used to take ADCP1 and CTD2
measurements. The behavior
of the fish underwater is
similar to the behavior of an
aircraft wing. When the fish
is towed by a boat the
geometry of the “fish” with
the water circulation create a
pressure difference between
the bottom and the top of the
fish. This pressure difference
generates “lift”. The lift
force, the traction force and
the buoyancy compensate the
weight of the towed system
and the measurement depth
Figure 7: Schematic of the towed fish, the position of the fixture
can be adjusted by changing holes and the hole to pass the cable through the hull of the fish.
1
2
ADCP = Acoustic Doppler Current Profiler.
CTD = Conductivity Temperature Depth.
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of the forward speed of the boat and the length of the cable used to tow the “fish”.
This system can also be used in a vertical profiling mode.
4.2.2 Main Housing
The main housing is designed to contain and protect the electronic components from water
and water pressure during deployment at depth.
The communication modules as well as the
controller, data acquisition cards, signal
generator, power amplifier, fuses, batteries,
power supplies and all the connecting wires are
contained in this housing.
It is a cylinder closed on one end made of
aluminum. It has been anodized for the
corrosion protection and has dimensions:
Diameter: 12 inches
Length: 23 inches
Thickness: 0.107 inches
Figure 8: Main housing without the end cap.
Weight: about 20 kg without the instruments.
Figure
9:
Top end cap
with all the
connectors,
the
swithches
and
the
vacuum
hole.
The other end of the cylinder is
a removable end cap in which
subsea connectors connect the
electronics inside the housing
with other electronics and the
monitors on the ship. There is
also a hole to make the vacuum
and test the integrity of the
housing seals.
The housing seal is created by
two o-rings that make the
junction between the cylinder
and the end cap fully water and pressure proof up to a depth of 500 m.
On this end cap a bracket is fixed to support all the hardware.
4.2.3 Hydrophone housings
The
hydrophones
housings are
made to hold the
hydrophone and
protect the pre
amplifiers, T/R
Diode boxes,
and transducers
from water and
water pressure.
They have a
cylinder shape
Figure 10: On the right
the
front
of
the
hydrophone
housing.
The hydrophone fit in
the hole and connects
with the pre amplifier
inside the main cylinder.
On the right, here is the
back of the housing. On
the end cap the subsea
connector can be seen
and in the background
the pre amplifier and
electric wires.
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Third year of engineering school report – Florian Aulanier
and are made with titanium. This metal has approximately the same mechanical properties as
steel but is lighter than steel and more resistant to corrosion.
Diameter: 3 inches.
Length: 4 inches
Thickness: 0.225 inches.
Weight: 900g without the instruments.
On one end of the housing a hole allows the face of the hydrophone to be directly in contact
with water. This aperture is made waterproof by two O-rings present on the hydrophone.
The other end cap is removable and holds the bracket which supports the pre amplifier and the
diode box. Subsea connectors go through this end cap to provide communication and power
supply to the electronic hardware inside the housing.
4.2.4 Camera housings
The camera housing is almost the same as the hydrophone housing but is slightly bigger and
one of its ends is a view port made with glass.
Diameter: 3 inches.
Length: 8.75 inches.
Thickness of the titanium part: 0.188 inches
View port thickness: 0.5 inches.
Weight: 900g without the camera.
4.2.5 Clamps
4.2.5.1 Fish/Main Housing and Hydrophone arms
The fixture between the
fish and the main housing
takes the shape of two
clamps half in plastic half
in stainless steel. These
clamps are screwed inside
the shell of the fish which
prevent the main housing
from strong hydrodynamic
constraints. Here under it
can be seen a schematic of
these clamps.
Figure 11: On
the right is the
front fixture and
on the left the
back one. The
main housing is
hold by the big
clamps the two
small ones are
for the arm
where
the
hydrophones are
fixed.
On these fixtures two small clamps on the bottom are used to hold an arm on which the
hydrophones and the camera will be mounted.
4.2.5.2 Hydrophone and Camera Alignment
The hydrophones and the camera are mounted together on a long arm using clamps and ball
joint fixtures from Ikelite. These special fixtures allow the hydrophones and the camera to be
aligned in three dimensions following the three degrees of freedom in rotation: +/-20° around
the x-axis, 360° around the y-axis and +/-90° around the z-axis (see Figure 12). This is helpful
for a precise alignment of all the sonar on the same field of view.
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Third year of engineering school report – Florian Aulanier
Figure 12: On the right it can be seen the whole arm with the clamps and the camera mounted on it. On
the left hand side, a zoom has been made on the swiveling ball joints.
4.3 Electronic components
The electronic part falls into the acoustic part, the video part and the communication part. As I
haven’t really worked on the communication part I won’t explain it in details.
4.3.1 Acoustics Part
4.3.1.1 Overview
The acoustical part of the system is composed of:
• Eight Hydrophones on the towed system and four on the sea bed system
• A signal generator
• A power amplifier
• Two Transmission/Reception (T/R) diode boxes
• Eight preamplifiers
• Data acquisition (DAQ) cards
• Personal Computer Unit (PCU)
• And Power Supplies.
The acoustical elements are connected together as shown on Figure 13. Two loops can be
seen on this scheme. A transmission loop and a reception loop connected between each other
by the environment.
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Figure 13: Scheme of the electronic hardware set up.
The signal produced by the signal generator is amplified by the power amplifier before being
sent in the water through two of the transducers. A T/R diode box allows each one of these
transducers functions as transmitters and receivers by isolating the receiver electronics from
the signal transmission.
Then the signal scattered by zooplankton is measured by six receivers (transducers) and the
two emitters/receivers which makes in total eight channels. Each channel is amplified by a
preamplifier before being acquired by the data acquisition cards and saved on a hard drive.
In the following, hardware specifications are summarized to give an overview of the system.
Detailed specifications are available in the documentation of each instrument.
4.3.1.2 Components
4.3.1.2.1 Transducers
The RESON TC-3021 transducers are broadband ultrasonic transducers optimized to run at an
approximate frequency of 2MHz. They are very directive, about 2.2° of aperture for the main
lobe, and the secondary lobe are less than -12.2dB than the main one (See exact specifications
in appendix. These specifications are slightly different for each transducer).
•
•
•
•
•
Maximum Input Voltage Tested: 250Vpp at 0.1%
duty cycle over a second.
Operating Depth: 700m
Survival Depth: 1000m
Transmitting sensitivity: 184 dB -/+ 3 dB at 2 Mhz
(ref V/µPa at 1m).
Receiving sensitivity: -207 dB -/+ 3 dB at 2MHz
(ref V/µPa).
IMPORTANT NOTE: Two phenomena can cause
Figure 14: Transducer RESON TC-3021.
the destruction of the transducers during the
transmission. An input voltage that is too large can cause a deformation of the piezoelectric
crystal beyond its limit of elasticity and break it. Then, even for lower voltage, the
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Third year of engineering school report – Florian Aulanier
transmission period has to be short enough to avoid overheating. Both maximum voltage and
transmission time length have to be considered to avoid damaging the transducer.
4.3.1.2.2 Power Amplifier
The KMA1040M16 from AR Worldwide is a
broadband power amplifier. The rated gain is 52dB
minimum for a 50 Ohms load and with a 2MHz signal
but a calibration sheet (see appendix) gives more
detail about the gain as a function of the frequency of
the input signal.
• Maximum input: 200mW which correspond to a
signal of 0.8V.
• Power supply: 28V at 16A DC.
• Average gain: 50 dB.
Two connectors are present on the back to allow the
user to turn it on in applying a signal of at least 5V
and turn it off in apply a signal lower than 0.1V.
Figure 15: Power Amplifier
Worldwide model KMA1040M16.
AR
IMPORTANT WARNING: The noise in the power amplifier can induce severe overheating,
very powerful output signals and be very destructive if no system is used to turn off the
amplifier and evacuate the heat when other instruments are connected to it. Noise higher than
75W has been measured at the output of the power amp when no output was expected. This
phenomenon might be caused by the noise and resonance effects in the circuits when the
amplifier is neither on nor off. So, make sure that a proper system - for example a resistor
between the source and the ground - is there to turn off the power amp when there is no input
signal which will avoid overheating and unexpected high voltages in output. A resistor of 1.2
KOhms between the on/off pin and the ground solved the problem in our case.
Moreover, even with a T/R diode box, the noise from the emission loop is amplified by the
power amp and pollutes the received signal during the reception phase. For this additional
reason the power amplifier has to be “gated” which means turned off during the reception
phase and turned on just before an acoustic pulse is to be sent.
4.3.1.2.3 Pre-Amplifiers
The pre-amplifiers are custom pre amps designed by N.T.S. Ultrasonics Pty Ltd to run
specifically with the RESON transducers. Two different modes are available:
•
•
the LO mode which allows an adjustable
gain from 5 to 70dB and a very low
noise level in output
the HI mode which add an amplification
of about 12dB in comparison to the LO
mode but add also noise.
For the MAZOOPS system the LO mode is
used and the gain of the preamps has been
set on 70 dB.
Figure 16: Top view of the pre amplififer without its
shield.
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Third year of engineering school report – Florian Aulanier
•
•
The output range of the pre amplifier is in the current settings: +/- 5 V.
The frequency range is: 1.75 to 2.5 MHz.
The input and output impedance of the preamps are made to
match with the RESON hydrophones.
• Input Impedance: approximately 30 Ohms.
• Output Impedance: 50 Ohms.
As some of the hydrophones are used to receive signal but
also to transmit it, the preamps have a voltage input
protection of 600 Vpp. It is possible to enable/disable this
protection with the input selector JP9 (see picture on the
right).
Figure 17: Input selector. The
input has a +/-600 V protection
when the selector is on the two left
pins.
The T/R hydrophones have to be set on protected to stand the high voltage transmitted pulses
whereas the receivers have to be set on unprotected. The latter option provides a lower noise
level and less harmonic distortion in the circuit and consequently better records.
4.3.1.2.4 Data Acquisition Board
The number of data acquisition channels depends
on the system considered. On the towed system 2
x 4 channels are used to look at zooplankton in
two opposite directions. In order to acquire these
eight channels two PXI-6115 boards are used with
4 analog inputs on each of them.
On the sea bed one only 4 DAQ channels will be
used and only one of the PXI-6115.
•
•
•
•
•
•
4 high-speed analog inputs, 10 MS/s per
channel, 12 bits resolution with onboard antiFigure 18: PXI-6115
aliasing filters
Maximum input range: ± 42 V
Minimum input range: ± 0.2 V
Deep onboard memory (32 or 64 MS)
Two 12-bit analog outputs, 4 MS/s single channel,
2.5 MS/s dual channel
8 digital I/O lines; two 24-bit counters; analog and digital triggering
4.3.1.2.5 Breakout box
The connector of the PXI-6115 is very complex. Breakout boxes are
necessary to access the pins which are to be used. For the MAZOOPS
system the breakout boxes are TB-2708. The four AI channel are
directly available thanks to SMB connectors as well as the counter
output 0, the 2 analog outputs, the AI sample clock and the AI start
trigger.
Other inputs and outputs are also available on the bottom of the
device thanks to a MFIT-Pigtail Cable Assembly. (Pinout shown
bellow)
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Figure 19:
Pinout of
the bottom
connector
of the TB2708.
4.3.1.2.6 Embedded Controller
The controller is a PXI-8108 from National Instrument.
Its main characteristics are:
• 2.53 GHz Intel Core 2 Duo T9400 dual-core
processor
• Up to 25 percent higher performance than the PXI8106
• 1 GB (1 x 1 GB DIMM) 800 MHz DDR2 RAM
standard, 4 GB maximum
• 10/100/1000BASE-TX (gigabit) Ethernet,
ExpressCard/34 slot, and 4 Hi-Speed USB ports
• Integrated hard drive, GPIB, serial, and other
peripheral I/O
Figure 20: PXI-8108.
4.3.1.2.7 Signal Generator
The signal generated with a NI PXI-5412. This
function generator is made to drive a 50 Ohms load
which is perfect regarding the fact that the input
impedance of the power amplifier is 50 Ohms. The
generation of arbitrary waveform at a maximum rate
of 100MS/s is more than sufficient to transmit a signal
with a maximum frequency of 2.5 MHz without
loosing information following the Shannon law.
4.3.2 Video Part
Figure 21: PXI-5412.
4.3.2.1 Overview
The video part is composed of the following elements:
• A camera;
• A controller (the same as the acoustical part one);
• 2 LED projectors;
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•
And the Power Supplies.
The video camera and the lights are synchronized with the acoustical transmissions to take
pictures of the field of view. These pictures provide data that can be used to verify or enhance
estimates of zooplankton taxa from acoustic data.
4.3.2.2 Components
4.3.2.2.1 Camera
The camera used for this system is a Basler Scout camera scA1400-17g.
• Resolution: 1392 x 1040 pixels
• Pixel Size: 6.45µm x 6.45µm
• Sensor type: CCD (Charge Coupled Device)
• Sensitivity: 13 p~.
• Maximum Frame Rate: 17 frame per second (fps)
• Color: Black and White.
• OFF to ON Time: about 10s.
This camera has a Gigabit Ethernet (GigE) interface
to transmit data.
It is possible to trigger the exposure with an external
signal 0-5V on line 1 and line 2 of the connector.
(See pinout in appendix)
Figure 22: Basler Scout camera scA1400-17g
with a Navitar NMV-75M1 lens.
4.3.2.2.2 Lens
The lens is a NMV-75M1 from NAVITAR Machine Vision. Its characteristics are:
• Focal Length: 75.0 mm
• F-Stop: 1.8-16 mm
• Iris Control: Manual.
• Focus Control: Manual.
• No zoom.
• Focusing range from the front of the lens: 0.5 m to infinity.
• Object Area at M.O.D (H x V): 55h x 41v.
• Field Angle (H x V): 6.68° x 5.03°
4.3.2.2.3 LED projectors
The projectors are green LED MultiSeaLite from DeapSea Power & Light.
These LED lights last longer than
halogen and classical lights and have a
better efficiency. The green is less
attenuated by seawater but has the
drawback of being visible by fishes and
zooplankton. However these lights
should be replaced by far-red lights that
are quasi-invisible for underwater
marine life.
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The main characteristics of these projectors are:
• Real Power: 44W.
• Beam Directivity: -/+ 15°.
• Input Voltage: 9-32V DC (Possibility to have AC supply versions).
• Current Draw: 550 mA at 120V AC.
• Full power rising time: 17ms for dimming voltage step of 0V to 5V.
• Rated Depth: 6000 m.
• Air Weight:
• LED Lifespan: 50,000 hours.
The dimming of the LED projectors can be controlled electronically. However the dimming
doesn’t allow turning the projectors off. However, he power supply of these projectors can
also be gated to be disabled and enabled so that the light can be turned respectively off and
on. Because this necessary step the time for the power supply to run with full power has to be
taken in count as well as the time for the light to operate at full power. As all the acoustics and
the camera are synchronized with the light this will in our case reduce the maximum ping rate
of the system.
4.3.3 Communication Part
The communication part relies on Ethernet network or DSL Network. The communication
module allows communicating with the instruments through the controller and retrieving data.
A 1 GB Ethernet network is also used for the communication between the camera and the
controller. As the controller has only one Ethernet connector an Ethernet switch is used to
manage the networks.
4.4 Software Part
4.4.1 General functioning
The programming of the MAZOOPS system takes the form of a Virtual Instrument (VI) built
with the Software LabVIEW by National Instrument. This software provides the graphical
user interface (GUI) for the system and drives the hardware. .
In the VI you can find all the main parts of a “classical language” program.
• First all the controls have to be set to their default value (OFF) to prevent the hardware
from starting unexpectedly.
• Then, two cases:
o either the CTD runs alone in order for the user to set the sonar parameters
(Sampling rate of the emission or reception, full scale for the data acquisition,
start power amplifier, start light …)
o or the CTD and the sonar run at the same time. This choice is made by
activating or deactivating the button “Sonar ON/OFF”. The default state is
sonar OFF.
• Thereafter the main part of the VI, all the buttons and channels are closed and deactivated
to turn all of the sonar components off.
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Initialization
Sonar OFF
• outputs at • Read and display
0V
CTD measurements
• buttons to • Sonar Settings
default state
(OFF)
Sonar ON
Finalization
• Read, save and
• outputs at
display CTD
0V
measurements
• buttons to
• Sonar: acoustic
default state
transmission,
(OFF)
acoustic acquisition,
camera, light, save
data, switches.
Figure 23: Scheme of the general organization of the virtual instrument.
4.4.2 Data acquisition (DAQ)
The DAQ part is realized with National Instruments PXI-6115 DAQ boards. These boards can
be interfaced in Labview with the DAQmx library which comes with the boards. In the case
of the MAZOOPS System the goal is to acquire a finite number of samples with the highest
rate possible - which has to be at least 2*2.5 MHz (maximum frequency of the transmit
signal) – and during a period of time long enough to get the echoes of the whole sampling
volume. The solution chosen here is to acquire 10MS/s during 3µs to be sure to get the all
the echoes.
Figure 24: Settings of the analog input for the data acquisition channels.
The DAQ is programmed following three successive steps: The initialization, the channel
reading, the end of the DAQ task. It is possible to open several analog inputs on the same
device with the same task but each device must have its own task.
During initialization several parameters have to be set:
• First, the Analog Input channels have to be selected and opened with the function Create
Task option Analog Input:Voltage of the DAQmx library in the menu Measurement I/O of
the function palette.
• Then the clock of the channel has to be set on finite samples using the function Clock. The
number of samples to acquire and the sampling frequency have to be specified here. The
clock is the signal which will regulate the data acquisition.
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•
The trigger signal is defined with the function Trigger. The trigger source can be selected
here and the trigger mode is set one rising edge of a digital output. As soon as a rising
edge is detected in the trigger signal the DAQ will start on the next acquisition.
As the two data acquisition boards have to be synchronized the properties of the first task (the
one of the master device) are collected with the property node function and given as
parameters to the slave device’s task. Sharing the clock and the trigger signal the two tasks are
completely synchronized and the two 4-analog input boards work as one 8-analog input
board.
Then, the eight channels are read to display and save data with the function Read channel set
on Analog Input: N Channels N Samples. The DAQ channels are with the PXI-6115 not
inherently retriggerable. The use of other channels (counter outputs) to make them
retriggerable in this case the sampling rate of the DAQ is not sufficient. The only solution to
reach a sampling rate of 10 MHz is to start and stop the task at the desired frequency. The
channels will start, wait for the trigger signal, start the acquisition and read 30000 samples per
channels, stop, display and/or save data, then start again following the number of echoes
which are to be recorded.
Figure 25: Reading part of the data acquisition task. Start task function and Stop task function are placed in a
while loop to make the data acquisition lines retriggerable.
When the whole process is finished, the DAQ task is cleared with the function Clear channel
and the eventual errors are displayed.
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Figure 26: At the end of the data acquisition part all the tasks are cleared and the
eventual error messages displayed.
4.4.3 Function generation
The function generator is a National Instrument PXI-5412 arbitrary waveform function
generator. This function generator is used to create the pulse transmitted in the water before
its amplification by the power amplifier. The maximum sampling rate of the function
generator is 100 MS/s which allows for transmitting oversampled or very high frequency
signals. The only drawback is the size of the file which is read to transmit the function which
increases with the sampling rate.
The LabVIEW library used to build this part of the VI is “NI Fgen” and can be found in the
menu “Measurement I/O” of the function palette. To generate pulses the following steps have
to be done:
Figure 20: Initialization of the function generation task. This task is retriggerable.
•
•
•
First, create a task to open the channel of the function generator and select the proper
output on the proper device (niFgen Initialize.vi).
Then with the other parameter function of the Labview library “NI FGen” set the task to
generate “arbitrary sequence” (niFgen Configure Output Mode.vi),
Choose the sampling rate (niFgen Set Sample Rate.vi),
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•
•
•
•
the way to sent the arbitrary waveform (single, burst, continuous,…) with niFgen
Configure Trigger Mode.vi. Here stepped means one generation per trigger signal. If a
trigger signal is emitted while the function generator is already running, the function
generator continues its emission ;
and the type of trigger (here Digital Edge) and trigger source (niFgen Configure Digital
Edge Start Trigger.vi).
Thereafter, the file containing the arbitrary function to be generated is read and converted
into a waveform variable (Read Waveform from File.vi). This waveform is displayed on
the front panel and converted into an arbitrary sequence (niFgen Create Arbitrary
Sequence.vi) and generated on the selected analog output channel.
It is possible to control the amplitude of the waveform using the niFgen configure
Arbitrary Sequence.vi which applies a gain on the output of the function generator. The
output voltage is defined in theory by the following relation:
Gain x File Waveform Amplitude = Output Amplitude.
•
It is then convenient to use +/-1V amplitude waveform file and be able to control the
output amplitude with the gain because the gain is directly the amplitude of the output
signal.
As the function generation is retriggerable it is necessary to start it only once at the beginning
of the sonar activation and stop it once at the end of the sonar measurement. All the trigger
signal in the meantime will cause the generation of the waveform file content except if the
function generator is already running.
To generate waveform files special VIs have been created. “MAZOOPS –
WaveformBuilder.vi” and “MAZOOPS – WaveformBuilder_InitialDelay.vi” can be used to
create the waveform files. They are almost the same Vis but the second one pads the
beginning of the waveform file with zeros. The format of the created files is “.wfm”.
4.4.4 Camera
The camera is interfaced with Labview through a 1 GB Ethernet connection and the software
NI Vision. The library used here is the IMAQdx library of Labview which comes with NI
Vision. Like the other acquisition tasks the camera task has an initialization part where all the
settings are defined, an image acquisition part and is cleared at the end.
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Figure 27: Camera settings and camera switch. On this figure it can be seen that after the camera
turned
on a delay is necessary to let the time for the PC to recognize the camera. This delay is about 10 ms in the case of the
MAZOOPS system.
Third year of engineering school report – Florian Aulanier
All the properties present in Measurement Automation eXplorer (MAX) can be set with
Labview. The main difference with the other channels is that all the properties are selected
with Property Node functions instead of special Labview functions.
In this VI the trigger properties are set on: Trigger activation: rising edge, Trigger mode: ON,
Trigger selector: Acquisition start, Trigger source: line 1or 2. The trigger is an external
trigger. The trigger sources: counter output 0 or counter output 1, are respectively linked with
the lines 1 and 2. Following the exposure time of the camera - superior or inferior at 5.1-5.3
ms (= 4.5 ms activation of the power amplifier + transmission time + 0.6-0.7 ms time for the
sound pulse to reach the target) - it is necessary to select line 1 if the exposure time is superior
at 5.3 ms or line 2 if it is less than 5.3 ms.
Figure 28: This figure shows the image acquisition function and the synchronization with the
lights. The time delay after the lights has been turned on is for the lights to reach the full power.
The fact that the image acquisition is dependant of the light generation requires synchronizing
it with the lights. Consequently, lights are turned on about 30 ms before the image acquisition
(17 ms for the light response and 13 ms for the power supply response) and stopped right
after.
4.4.5 Synchronization and counter outputs
When the sonar is active all the functions and instruments have to be synchronized with more
or less precision.
The synchronization between the power amplification, the signal generation, the data
acquisition and the camera has to be precise and is made with two counter outputs (Create:
Counter Output: Pulse frequency in the library DAQmx).
The counter output 0 (CTR 0 Out) controls the power amplifier gate and the external trigger
signal for the camera when the exposure time is long (>5.2 ms).
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The counter output 1 (CTR 1 Out) controls the function generator, the data acquisition and the
camera when the exposure time is less than 5.2 ms.
Figure 29: The two counter outputs are created on the same task and share in this way the same clock.
An initial delay is added to the second counter output to rule the delay between the first and the second
counter output.
This synchronization insures that the power amplifier is ON during the transmission in letting
an delay between CTR 0 and CTR 1 and OFF during the reception to avoid addition of noise.
At the same time it makes the camera time exposure and the acoustic time exposure overlap to
be sure to have acoustic and image data of the same phenomenon.
NOTE: It is possible to set the counter output pulse frequency, the number of cycles to
generate on the counter output, and make it retriggerable. However this implicitly uses the
other counter output to gate the first one and allow the regeneration of the pulse train. In this
case it is only possible to use the two counters on the same task because the number of cycles
is set to 1 and doesn’t need any gate for the regeneration.
Other instruments have to be synchronized with less precision. The lights have to be turned
ON enough time in advance to reach the full power before the exposition of the camera starts
and turned OFF once the exposition finished. This synchronization is made with software
priority i.e. the order in which the program executes itself.
4.4.6 Raw Data Display
In order to follow the acoustic measurements in real time, raw acoustic data in function of the
number of samples acquired are displayed on the front panel. This display can be disabled to
use less computer resources and increase the frequency of the ping emission.
4.4.7 Data Saving
The data acquisition can be enabled/disabled with the “Save” button.
Image and acoustic data are saved in the same folder. The folder location can be selected in
the data directory box on the front panel. The name of the folder is composed of a prefix, the
one in the “experiment name” box on the front panel, and a time stamp of the moment when
the save button has been switched on, separated by an underscore symbol.
Inside the folder there is a text file with all the sonar settings used for the record. The name of
this file is the same as the folder one.
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Acoustic data are stored as scattering recorder data file (.srdf). This format can be read using a
MATLAB program readSRDF.m. For each index of the loop there is one file containing the
30000 acoustic samples (3 ms of acoustic data). The filename starts by the name of the folder
and is appended with the index number of the loop preceded by an underscore symbol.
Image data are recorded with in “.TIFF” format using packed pits and LZW compression, and
the resolution of the image acquisition is 12 bits per pixels. The image file name is the same
as the corresponding acoustic file, format extension excepted.
4.4.8 Light Dimming
The LED projectors have 0-to-5V signal dimming input. The dimming control is realized with
the analog output 0 (AO 0) of the master device available directly on the breakout box. This
AO has to be set before the sonar starts and is an adjustable DC voltage output.
Figure 30: LED projectors dimming task. On the left the channel is opened and written at the voltage
seleccted on the front panel of the VI. On the right the AO channel is written to 0 and closed.
The creation of an analog output (function: Create: Analog Output: Voltage) and its writing
(Write: Analog output: Double, 1 Channel 1 Sample) of an analog output task during the
initialization are sufficient to serve as a dimming signal. This channel is then written to 0 V
after the sonar use and closed.
4.4.9 Switches
Several ON/OFF switches are needed to turn the instrument on or off and avoid overheating
and overconsumption of energy. The power amplifier, lights, and camera have their own
switch.
These switches are made with simple digital outputs which are written with a Boolean switch
present on the front panel and written back to 0 at the end of the VI. They appear in
LabVIEW as the functions Create: Digital Output ; Write: Digital Output: Boolean 1 line 1
point. This function can write True (5V) or False (0V) data on the DO.
However each switch line has its particularities.
The power amplifier switch turns simply the power amplifier to ON (when button enabled) at
the beginning of the sonar functioning and stop at the end of it before the system goes back to
the default case where only the CTD is running.
The light switch DO is also used to turn the light ON when the camera is capturing a picture
and OFF when there is no image acquisition. This blinking state is only possible when the
light control is enabled.
The function ON/OFF of the camera is also a little different. As it is not very good for the
camera to turn ON and OFF frequently and as it takes a long time for the camera to be
recognized by the PC, the camera needs to be activated at the beginning of the sonar use and
turned OFF only when the user quits completely the VI i.e. during the finalization phase.
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Therefore the DO stays on high state for the first use of the sonar until the user press the
“quit” button.
4.4.10
Front Panel
LabVIEW offers also a nice graphical interface called “front panel” of the VI. For the front
panel of the MAZOOPS VI it has been chosen to enhance the visualization of the
measurements.
The CTD measurements are visible in the CTD box close to the CTD settings. The image of
the last snapshot is displayed on the middle top of the front panel.
Acoustic data related to the image are at the same time displayed under the image. However,
only four hydrophones (four analog inputs of either the master device or the slave device =
one of the two sides) can be displayed at the same time. Tabs allow the user to select the
device or side to visualize.
Figure 31: Front panel of the MAZOOPS Virtual Instrument.
Then, all the parameters of the analog input channels and analog output channel can be
accessed from the front panel. The most frequently used controls are the function generation,
light control, CTD, data directory for saving and sonar frequency parameters are available in
the “Parameter 1” tab. The rest: data acquisition channel parameters are available in the tab
“Parameter 2”.
The three buttons on the top left part of the VI are the most important controls of this front
panel.
• The “sonar ON/OFF” button launches or stops the initialization of the instruments, the
data acquisition and the signal generation.
• The “Power Amplifier ON/OFF” manages the power amplification and so the arrival of
potentially high power signals in the hydrophones.
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•
The “Quit” button permits the user to stop completely the VI, stop all the instruments and
set all the output to 0V.
IMPORTANT WARNING: The hydrophones have to be underwater when the power
amplification is ON. The transmission of acoustic signal in the air can result in heavy
damages for the T/R hydrophones.
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5 Internship development
5.1 Background
5.1.1 Goal
The objective of the MAZOOPS system is to provide a non intrusive way to characterize
zooplankton distribution and abundance in the ocean. Precise optical solutions have already
been developed that use high definition cameras but are limited in range because of the strong
attenuation of electromagnetic waves underwater. The idea is to use high frequency (MHz)
acoustic waves and multiple angles to infer zooplankton characteristics.
Several ways to characterize zooplankton abundance from acoustic backscattering have been
tried in the past, but the complexity of the information which can be collected through
backscattering hasn’t permitted scientists to come out with a simple way of classify
zooplankton. Indeed the characteristics of the backscattered signal depend on many factors as:
orientation, size, water relative density of the scatterer. Each of theses parameters affect
sounds in the same ways (intensity and interferences) which doesn’t permit one to distinguish
one from the other in a simple manner.
Based on the previous work of Paul Roberts and Jules Jaffe3, it has been shown that using
scattered sound from different angles with a broadband signal allows better results in
zooplankton and fish classification partially because of the unknown orientation of the animal
can be sorted out. The MAZOOPS project is the direct follow up of Paul Roberts’ thesis and
consists in making instruments to get information about zooplankton distribution in the ocean.
Zooplankton being the food of many other marine animals this project will hopefully yield a
system that can be used to further our understanding of marine ecosystems.
5.1.2 Zooplankton
The system was tested with two different species of zooplankton: mysids and copepods. This
choice has been made because euphausiids and copepod are two dominant taxa in the marine
ecosystem and play an important role in global ecology and carbon cycle. Mysids have a
shape very similar to the euphausiids and can be captured easily along the Californian coast
where copepods can be found too.
Figure 1: On the left is a specimen of mysid and on the right a copepod.
3
Multiple angle acoustic classification of zooplankton, Paul L. D. Roberts and Jules S. Jaffe, JASA,
April 2007.
Classification of live, untethered zooplankton from observations of multiple-angle acoustic scatter, Paul
L. D. Roberts and Jules S. Jaffe, JASA, August 2008.
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Mysids are shrimp like crustaceans with length typically between 4mm and 1cm for adult
individual.
Some polar specimens of copepods can reach the size of 1cm but they usually range between
1 and 3 mm in length.
The main differences between mysids and copepods are first the size (copepods are smaller
than mysids) and mysids have a more elongated body than copepods which is of great interest
regarding acoustic classification. The typical target strengths of these animals are -90dB for
mysids and -100dB for copepods.
5.1.3 Sonar equation
The sonar equation shows the energy conservation of the sound wave along its trip between
the emission and the reception. This equation is used to estimate the possibility of detection of
the target. Commonly the values representing the energy level are converted in decibels to
make the calculation additive rather than multiplicative. This conversion requires one to use
references levels which are usually the Pascal or Micro Pascal for the acoustic pressure and
the Volt for the electrical signals.
Figure 32: Illustration of the sonar equation.
On the Figure 32 is an illustrative explanation of the sonar equation. With the scheme notation
the sonar equation is:
EL = SL – 2*TL + TS – (NL-DI)
Where:
• EL is the Echo Level received by the transducer.
• SL is the transmitted Sound Level.
• TL is the Transmission Loss and corresponds to the attenuation of the sound in the water.
It is counted twice one for the trip between the emitter and the target, and once for the trip
between the target and the receiver.
• NL is the Noise Level and correspond to the energy of the signal covered by the ambient
noise and so, not exploitable.
• Finally, DI is the directivity of the receiver which is the fact that only the part of the
acoustic signal coming into the reception cone is taken in count. Lots of noise come from
the other directions but are not captured by the receiver.
Sound/voltage conversion and post processing methods (filter, cross correlation between the
emitted signal and the received signal, etc…) add gain and/or some losses too to this sonar
equation.
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5.2 Getting in touch with the MAZOOPS project
The first two months were essentially dedicated to improving my background knowledge
about the field and get in touch with all the electronic equipment.
I first studied in depth the articles Multiple angle acoustic classification of zooplankton and
Classification of live, untethered zooplankton from observations of multiple-angle acoustic
scatter written by Dr. Paul Robert and Dr. Jules Jaffe.
The first article compares different methods to process zooplankton backscattering data issued
from computer simulations. The second one deals with the experimental setup and the data
analysis of a laboratory experiment of a multi angle acoustic apparatus made on living
zooplankton.
Then, in order to extend Paul Roberts’ work to the developed of a field system, I had to learn
how to program virtual instruments (VIs) with the software LabVIEW developed by National
Instruments (NI). This software offers at the same time the possibility to interface and control
simply electronic hardware. The tutorials, the examples, as well as the support provide by NI
helped me to understand Paul’s previous work and then develop new VIs to make the
software part of the sonar.
The development of the MAZOOPS required collaboration with the machine shop of UCSD
which was in charge of designing the mechanical structure of the sonar and building custom
mechanical elements. Therefore, I had to meet people and get in touch with the role of each
person but also the location of the different workshops and laboratories.
Acoustic and electronic hardware are fragile and expensive. That is why before starting to
work on the instruments used to make the MAZOOPS I had to practice with other
instruments.
The first test was to set up a simplified version of Paul Roberts’ experiment. Data were
aquired through 1 NI PXI-8176 controller, 2 DAQ NI PXI-6115 boards and several
Panametric 5670 broadband preamplifiers. The transmit signal was generated by a Stanford
Research DS345 function generator and an ENI AP400B 400W power amplifier. The
transducers were CDINT 2.25 MHz 1.0”.
The goal of this experiment was first to get a signal from a direct emission-reception, then
from the reflection from the back of the tank and finally from the backscattering of a piece of
dental floss and a fishing line.
The main differences between the Paul’s experiment and this experiment were the size of the
tank and the type of hydrophones. The OASIS tank (tank where Paul did his experiment) is
4m long by 2.5m wide by 2m depth whereas the one I used was 2m long by 1.5m wide and
1m depth. This implies that reflections against the sides of the tank are more easily visible and
can interfere more with the echo from the target.
The fact that the hydrophones were also very directive added to the difficulty to get good
signal. The horizontal alignment of the hydrophones was made thanks to a vertical fishing line
and the vertical alignment was made in maximizing the echo.
However long hours of struggle payed off and at the end I was able to get a good
backscattering signal from a sample of fishing line.
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5.3 Sonar development
Then all the work of the sonar development was to integrate all the hardware in the housing.
Before this step everything has to be programmed, assembled and tested outside the housing.
The set up described for the “get in touch” experiment was progressively replaced by the
hardware described in Part 3 of this report to achieve the final set up.
The first step was to replace the hydrophones CDINT by the RESON one, and then the power
amplifier. At this step, I met some problem due to the combination of noise, grounding and
high power amplification. It turned out that initially the power amplifier was not off but was
floating between the two states ON/OFF. This causes the amplification of the noise, added to
resonance phenomenon in the circuits. The result of this process was an abnormal high power
signal at the output of the power amplifier when the input was set to 0V. The solution, a pull
down resistor of 1.2 KOhms on the gate of the power amplifier, was found in collaboration
with Robert Glatts.
Once this step was over, and after having tried to use the PXI-6115 as function generator the
integration of the arbitrary waveform generator NI PXI-5412 in the controller had to be done.
This integration needed a lot of work in Labview programming. The main problem was to
synchronize all the different hardware together with a restricted number of channels, channels
settings and trigger mode.
As soon as the VI was running a first calibration of the “Labview + power amplifier” system
was made to know exactly the voltage at the output of the power amplifier and avoid
damaging the transducers.
Then, once the Panametrics preamplifiers
were replaced by the custom made N.T.S
Ultrasonic ones all the equipment was set up
in the OASIS Lab where there is a bigger tank
that it is possible to fill up with sea water. A
little detour by the machine shop to adapt
Paul’s old set up to the new one, and the
system was installed in the OASIS tank. Tests
were performed and showed that hydrophone
supports did not allow us to optimally align
the system. The next step was then to design Figure 3: Picture of the 5mm calibration sphere and
the really thin acrylic strand.
and build the future hydrophone’s support of
the MAZOOP system. The final solution was to use Ikelite ball joints (ball joints for camera
support) that we adapted to fit our system. Supports to fix the main housing under the towed
fish were also designed and ordered at this time.
The new support built, the hydrophones were aligned and ready for the calibration of the
acoustic loop. This calibration aimed to know the amplitude of the received signal for objects
with known target strength. 75µm nylon fishing line and tungsten spheres of several diameters
(5mm, 2mm) were used to carry out the calibration and be ready to do an experiment with
zooplankton. One challenge of the calibration was to find a way to keep the calibration sphere
in the FOV. This was realized with a thin acrylic strand and a small droplet of super glue.
When the characteristics of the sonar are all known, it is possible to estimate the signal to
noise ratio (SNR) for a given target strength. An SNR of at least 20dB is needed to facilitate
post processing and analysis. The results for the 5mm sphere showed a SNR of a least 45dB
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and up to 70 dB for a target strength of -60 dB which was encouraging considering that the
target strength of zooplankton is around -100 dB.
Figure 33: Sound noise ratio in function of the transmit voltage for a 5mm tungsten sphere.
Then the experiment with live zooplankton was performed. (See details in the next paragraph)
Some delay development of the camera and the hydrophone housing permitted to check the
functioning of the main housing fixtures and send the fish to the machine shop in order to be
sand blasted and repainted.
Afterward, the other parts of the MAZOOPS were added to the acoustic system. The camera
and the LED lights were synchronized with the acoustic data acquisition to capture an image
of the FOV during the scattering of the sound wave against the target. This image will allow
us to validate the results from the acoustic system. At the same time the system was integrated
into the housing with the power part and the communication part.
The last parts to be ready were the towed fish and the hydrophones housing. It was then
decided to make tests with the whole system except the fish as soon as the hydrophone
housing will be ready. These trials will be done after the writing of this report.
5.4 Experiment
5.4.1 Experimental set up
The experiment has been done to see if the MAZOOPS system permitted to see the
zooplankton and characterize them. The experiment was conducted in the OASIS Lab with a
set up of 3 receivers and 1 transmitter/receiver. The hydrophones were positioned linearly
along an array and aligned so that their beams intersect about 1.14 m away from the array
baseline (see Figure 34).
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Figure 34: Scheme of the experimental set up.
During this experiment a 1.5 MHz to 2.5 MHz linearly frequency modulated signal with a
cosine squared envelope was transmitted. Different transmission powers were tested first to
simply see if it was possible to get echoes from the two types of zooplankton (copepods and
mysids) and then to see how sensitive the sonar was.
A System of gravity pumps were made to get the zooplankton inside the field of view. As
mysids can swim very fast and escape quickly from the field of view they had to be sedated
with clove oil. As soon as they moved less but were still alive they were put in a funnel above
the field of view and sank in the field of view. For the copepods, they were pumped up
Figure 6: On the left, the hydrophones on the
frame in the OASIS Lab. On the right, pump
sytem for the copepods.
through the FOV with a system of pipe ending under the FOV. (see Erreur ! Source du
renvoi introuvable.)
Another difficulty for this experiment was the time. Indeed, keeping the zooplankton alive
becomes difficult after 5 hours leaving little time to make adjustments to the experiment
configuration. Everything has to be ready in advance and previous experience in laboratory
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experiments involving living animals is a real advantage that I did not have for this
experiment.
5.4.2 Data Processing
The main objective of the data processing of this experiment was to calculate and compare the
target strengths recorded with the sonar system to the theoretical ones and the ones found by
Paul in his previous experiment.
To find the target strength the sonar equation has been used. The transmit voltage, transducers
properties, the attenuation of sound in sea water are known and allow one to calculate the
target strength on some clean samples.
Vr = 20*log10(
Vt
)+EmitSens+GPreAmp +TS-40*log10(range)-2*range*absorption(in dB/meter)+RecepSens
V0
Where:
• range is the target range: 1.14 m,
• Vt is the rms transmit voltage,
• Vr is the received rms voltage,
• EmitSens is the sensitivity of the transducer in emission: +185dB ref. µPa/V at 1m.
• RecepSens is the sensitivity of the transducer in reception: -205dB ref V/µPa
• TS is the target strength,
• Absorption is the attenuation of the sound in the water: about 1 dB/meter.
• And GPreAmp is the gain of the preamplifiers: 70dB.
Then the post processing with a match filter adds about 20dB which have to be taken in count
in the calculation of the target strength.
For the copepods target strength has been found around -110dB which matched the results of
previous work and theory. Concerning the mysids, the presence of bubbles during the
experiment and the fact that the video part of the system was not ready did not permit us to
find echoes only due to mysids backscattering.
At this point the system was considered satisfying considering that if it was possible to get
echoes from copepods it would be also possible to get some from mysids since they typically
have stronger target strength. Then, I had to return to assemble and add all of the different
parts of the system. I had the hope to be able to try the complete system to get other data but
this time with the help of the camera but the building of the sonar finally took more time than
what it was foreseen and didn’t allow me to do another experiment and push further the signal
processing.
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6 Conclusions
This internship abroad in research and development in university laboratory was very useful
to use my theoretical education and complement it with practical skills. I was able to improve
a lot my knowledge in underwater acoustic system, electronic but also in hardware machining
and design. Lots of lab work taught me deal with unexpected problems. I have also learnt a lot
about experiment involving animal where the time is more than precious and where
everything has to be foreseen in advance to take the most of the short period where the
animals are alive. As an important part of my work I learned and become proficient in
LabVIEW. I can solve problems quickly in software and know where to look for existing
solutions. The opportunity of doing a laboratory experiment having been given to me, made
me realize the necessity of a good preparation of the experiment what I haven’t done enough
in setting up this one. The only regret I have is not having had enough time to go deeper in the
data processing research.
Personally, the fact that I had to communicate with the other members of my team but also
contact persons from other industries to realize my project, helped me to improve my way of
communicate on my work and organize team work. In this case it is crucial to understand the
need of every person or organization involved in the project and cope with everybody’s
demand. Since this internship occurred in the United States I had also the chance to practice
and improve a lot my English speaking skill, see another way to work and develop work
connections with people.
To conclude, this experience reinforced my desire to continue toward a PhD and open my
mind over the diversity of fascinating topics to study.
Page 33 sur 33
Appendix. Third year of engineering school report – Florian Aulanier
Appendix
APPENDIX...........................................................................................1
TABLE FOR THE APTE DIAGRAM ........................................................2
POWER AMPLIFIER CALIBRATION CURVES WITH TWO FIFTY OHMS
LOAD ...................................................................................................3
MATLAB CODE TO VISUALIZE .SRDF FILES .....................................4
MATCHED FILTER WITH MATLAB ....................................................6
MAIN HOUSING CLAMP SCHEMATIC ....................................................8
Page 1 of 8
Enable the user to record and visualize in
real time Conductivity Temperature
Density.
Resist to the marine environment.
Be corrosion resistant.
PF2
1
PF = Principal Function; CF = Constraint Function.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Power supply
Towing system
presence.
Ergonomy.
•
Autonomy length.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Conception.
Conception.
Sea conditions.
Conception.
Material.
Coating.
Measurement rate.
Precision.
Criterion
Acoustic sampling rate.
Acoustic record length.
Image per second.
Range.
Easy to use and
handful.
< 12 hours
Yes
>5 hours
Deployable during 5
hours twice a day
during one week.
IP68.
52 bars.
Beaufort 2.
No natural light.
Level
10 MS/s
Enough to get FOV
echoes.
1 image of 1392 x
1040 16 bit square
pixels of 6.45 µm.
1 m.
1 CTD measurement/s
0.1 unit
Table 1: Need Specifications of the MAZOOPS System
Be user friendly.
CF4
CF2.2
CF3
Be waterproof.
Resist to the water pressure.
Be deployable.
Be able to record images in the dark.
Adapt itself to energy resources.
Be autonomous in energy during
deployments
Be rechargeable.
Be towable by an oceanographic vessel.
CF1.2
CF1.3
CF1.4
CF1.5
CF2
CF2.1
CF1
CF1.1
Designation
Enable the user to record and visualize in
real
time
optic
and
acoustic
measurements of zooplankton.
Number1
PF1
Table for the APTE diagram
Appendix. Third year of engineering school report – Florian Aulanier
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
NA
10 min
None
10 min
Page 2 of 8
None.
+/- 1 bar.
+/- 1 Beaufort.
None.
More but not less.
More but not less
More but not less
Flexibility
Can be superior but
not inferior.
None.
Can be superior but
not inferior.
+ 1m.
Appendix. Third year of engineering school report – Florian Aulanier
Power Amplifier Calibration Curves with two fifty Ohms load
Page 3 of 8
Appendix. Third year of engineering school report – Florian Aulanier
MATLAB code to visualize .SRDF files
clear all
close all
ping = 1 ; % Pings per set.
channel = 8 ; % Number of channels.
fs = 10^7; % Sampling rate.
visual_ch = 2 ; % Channel you want to visualize.
%path
=
'E:\MAZOOPS\Data\copepods3_20090730043629\copepods3_2009073004
3629' ;
path
=
'E:\MAZOOPS\Data\copepods2_20090730043629\copepods2_2009073004
3629' ;
%path
=
'E:\MAZOOPS\Data\mysids5_20090730052845\mysids5_20090730052845
';
%path
=
'E:\MAZOOPS\Data\mysids3_20090730050818\mysids3_20090730050818
' ;
%path
=
'E:\MAZOOPS\Data\mysids2_20090730024221\mysids2_20090730024221
' ;
%path
=
'E:\MAZOOPS\Data\mysids1_20090730000540\mysids1_20090730000540
' ;
%path
=
'E:\MAZOOPS\Data\copepods1_20090730030059\copepods1_2009073003
0059' ;
ipingnum = 0 ; % initial ping number.
epingnum = 0 ; % end ping number.
data = [] ;
for nn = ipingnum:epingnum
if nn < 10
fname = [path,'_000',num2str(nn),'.srdf'] ;
elseif 10 <= nn & nn < 100
fname = [path,'_00',num2str(nn),'.srdf'] ;
elseif 100 <= nn & nn < 1000
fname = [path,'_0',num2str(nn),'.srdf'] ;
else
fname = [path,'_',num2str(nn),'.srdf'] ;
end
%'\\192.168.1.7\data\WhiteStrand_20090724040903\WhiteStrand_20
090724040903_0047.srdf';
%'\\192.168.1.7\Data\FishingLine_20090722061542\FishingLine_20
090722061542_0023.srdf';
Page 4 of 8
Appendix. Third year of engineering school report – Florian Aulanier
%'\\192.168.1.7\Data\75umFishingLine50Vpp_20090723035009\75umF
ishingLine50Vpp_20090723035009_0036.srdf';
[idata,datain] = gen_read_srdf(fname,ping,channel);
data = [data; idata] ;
end
%
fname
=
['\\192.168.1.7\data\mysids1_20090730000540\mysids1_2009073000
0540_','','.srdf'] ;
% [idata,datain] = gen_read_srdf(fname,ping,channel);
% data = [data; idata] ;
t = [0:size(data,1)-1]/fs;
figure
subplot(2,1,1)
plot(t,data(:,visual_ch))
% plot(t,data(:,2,1))
%h1 = plot(data(:,1,1))
subplot(2,1,2)
% plot(t,data(:,1,10))
% %h2 = plot(data(:,1,10))
nfft = 512 ;
window = nfft ;
numoverlap = fix(0.75*window) ;
specgram(data(:,visual_ch,1),nfft,fs,window,numoverlap)
% load('Emitsig3.mat')
% specgram(emitsig3,nfft,fs,window,numoverlap)
Page 5 of 8
Appendix. Third year of engineering school report – Florian Aulanier
Matched filter with MATLAB
clear all
close all
ping = 1 ; % Pings per set.
channel = 8 ; % Number of channels.
fs = 10^7; % Sampling rate.
visual_ch = 2 ; % Channel you want to visualize.
%path
=
'E:\MAZOOPS\Data\copepods3_20090730043629\copepods3_2009073004
3629' ;
path
=
'E:\MAZOOPS\Data\copepods2_20090730043629\copepods2_2009073004
3629' ;
%path
=
'E:\MAZOOPS\Data\mysids5_20090730052845\mysids5_20090730052845
';
%path
=
'E:\MAZOOPS\Data\mysids3_20090730050818\mysids3_20090730050818
' ;
%path
=
'E:\MAZOOPS\Data\mysids2_20090730024221\mysids2_20090730024221
' ;
%path
=
'E:\MAZOOPS\Data\mysids1_20090730000540\mysids1_20090730000540
' ;
%path
=
'E:\MAZOOPS\Data\copepods1_20090730030059\copepods1_2009073003
0059' ;
ipingnum = 0 ; % initial ping number.
epingnum = 0 ; % end ping number.
data = [] ;
for nn = ipingnum:epingnum
if nn < 10
fname = [path,'_000',num2str(nn),'.srdf'] ;
elseif 10 <= nn & nn < 100
fname = [path,'_00',num2str(nn),'.srdf'] ;
elseif 100 <= nn & nn < 1000
fname = [path,'_0',num2str(nn),'.srdf'] ;
else
fname = [path,'_',num2str(nn),'.srdf'] ;
end
%'\\192.168.1.7\data\WhiteStrand_20090724040903\WhiteStrand_20
090724040903_0047.srdf';
%'\\192.168.1.7\Data\FishingLine_20090722061542\FishingLine_20
090722061542_0023.srdf';
Page 6 of 8
Appendix. Third year of engineering school report – Florian Aulanier
%'\\192.168.1.7\Data\75umFishingLine50Vpp_20090723035009\75umF
ishingLine50Vpp_20090723035009_0036.srdf';
[idata,datain] = gen_read_srdf(fname,ping,channel);
data = [data; idata] ;
end
%
fname
=
['\\192.168.1.7\data\mysids1_20090730000540\mysids1_2009073000
0540_','','.srdf'] ;
% [idata,datain] = gen_read_srdf(fname,ping,channel);
% data = [data; idata] ;
t = [0:size(data,1)-1]/fs;
figure
subplot(2,1,1)
plot(t,data(:,visual_ch))
% plot(t,data(:,2,1))
%h1 = plot(data(:,1,1))
subplot(2,1,2)
% plot(t,data(:,1,10))
% %h2 = plot(data(:,1,10))
nfft = 512 ;
window = nfft ;
numoverlap = fix(0.75*window) ;
specgram(data(:,visual_ch,1),nfft,fs,window,numoverlap)
% load('Emitsig3.mat')
% specgram(emitsig3,nfft,fs,window,numoverlap)
Page 7 of 8
Appendix. Third year of engineering school report – Florian Aulanier
Main housing clamp schematic
Page 8 of 8