ohmex SONARMITE v3.0 User manual

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SONARMITE v3.0
PORTABLE BLUETOOTH ECHO SOUNDER
Ohmex is a company formed to manufacture and distribute products designed by Lymtech LLC, a company founded on
technological innovation and design. The company prides itself on being the first to produce products in the field of
instrumentation and software used within the Earth Science sectors. Achievements to date include DGM ,the first digital ground
modelling software to run a standard PC, SONARMITE, the first truly portable echo sounder, TIDALITE the first portable Tide
Gauge, EDAS, Integrated tide and weather networked software for use by ports and harbours. WinSTRUMENTATION - The
integration of Instrumentation, Wireless networks and modern portable computer equipment.

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Contents
SONARMITE v3.0........................................................................................................1
PORTABLE BLUETOOTH ECHO SOUNDER......................................................1
INTRODUCTION .........................................................................................................3
Typical Use of the Equipment ...................................................................................4
Equipment Supplied...................................................................................................5
INSTALLATION & USE..............................................................................................6
Switching the System On...........................................................................................6
Data Collection Techniques.......................................................................................6
Barchecking ...............................................................................................................6
Internal Battery Charging ..........................................................................................7
Reverse Voltage Protection........................................................................................8
Weatherproofing........................................................................................................8
DEPTH TRANSDUCER...............................................................................................9
Transducer Mounting.................................................................................................9
Avoid Stressing Transducers ...................................................................................10
BLUETOOTH INTERFACE.......................................................................................11
BluWave ID/Password code................................................................................11
Bluetooth™ Serial Port Profile................................................................................11
Features................................................................................................................11
Bluetooth - actual range of the device. ....................................................................12
Connecting to another Bluetooth™ PC/PDA ..........................................................12
CONNECTIONS .........................................................................................................13
„Computer‟ connection ............................................................................................13
„Transducer/Charger‟ connection ............................................................................13
APPENDIX..................................................................................................................14
SonarMite Settings...................................................................................................14
Flash Memory..........................................................................................................14
SonarMite Serial Commands...................................................................................15
Memory Operations.............................................................................................15
General Operations ..................................................................................................16
Typical Windows HyperTerminal settings..............................................................20
Version 3 modifications...........................................................................................21

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INTRODUCTION
The SonarMite Echo Sounder is the result of nearly two years research and
development to further extend the boundaries of shallow water hydrographic
surveying equipment. The introduction by Ohmex in 1997 of the SonarLite, the
worlds first truly portable echo sounder system, has been a hard act to follow and it
remains the portable instrument of choice in many survey companies around the
world. The release of the SonarMite instrument marks the next stage introducing a
series of equipment designed around the WinSTRUMENT concept using the latest
portable computers integrated with new measurement technologies.
Throughout the Hydrographic world the term 'Black Box' has become a euphemism
for a device that has a minimal user interface and normally requires connection to a
PC to be of any use ! In most cases these boxes are a cut down version of a more
conventional instrument without all the features of the full system. The SonarMite
extends this idea of a rugged design and minimalist interface to produce a 'Blue Box'
system where the user interface is provided by integrated software running on a
portable computer connected via a Bluetooth link. The use of wireless technology
enables the instrument to be waterproof and used in a hostile environment while the
more sensitive computer features can be located in a more user friendly environment
up to 50m away from the instrument.
The SonarMite instrument uses the same 'Smart' integrated transducer technology
used in the SonarLite system, in addition to highly reliable bottom tracking algorithms
using DSP techniques the system also outputs a quality value associated with every
depth measurement made. The popular SonarVista software has been updated to
SonarVista, in addition to the standard post-processing and editing features found in
the SonarMite software the program now includes extended features to implement the
additional measurements produced by the SonarMite. Software for the 'front end' of
the SonarMite is available to run on a wide range of devices from Pocket PCs through
to the full range of desktop systems running the Windows operating system. In the
event the user already has data acquisition software the SonarMite can be used as a
simple „dumb‟ echo sounder that can be configured in wide variety of formats.

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Typical Use of the Equipment
The SonarMite Portable Echo Sounder has been designed to provide a portable
instrument that provides the facilities of a „professional‟ sounder at the cost and
performance of a „fish finder‟ device. It is important to recognize what the differences
are between these two types of echo sounder. The „fish finder‟ or leisure craft devices
are primarily concerned with two functions, finding fish in the water column below
the boat by sensing returns from their swim bladders and providing a bottom
tracking/smoothing algorithm to detect average water depth below the boats hull.
Survey sounders are designed to provide a large number of pings with as little
processing of the raw data as possible to define the bottom in as fine detail as
possible. Of major concern in a survey sounder is a narrow beam width to prevent
averaging of the returned signal.
The SonarMite uses Active Transducers, these are digital as opposed to analogue
components and use microprocessors to synthesize transmitted frequencies and to
interpret the return signals. The devices incorporate state of the art DSP and filtering
techniques to reduce noise and improve depth tracking. These devices are supplied
encapsulated in resin and have no serviceable parts. The connecting cable to the
transducer carries only low DC voltage and digital stream data, none of the EMC
problems associated with conventional analogue devices apply.
To improve weatherproofing and to avoid connection problems the SonarMite has
two connectors that provide all the I/O required by the device. One of the connectors
also includes a return pin to enable the system to switch on by cable connection rather
than using a switch. Cables to the device can be connected simultaneously (e.g.
Transducer on „TXR‟ port and Serial Data Cable on „PC‟ Port).

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Equipment Supplied
The SonarMite is supplied as standard with the following list of equipment …
SonarMite main processor unit c/w Bluetooth Antenna
Universal EU/US/UK internal battery charger
„Smart‟ depth transducer c/w 5m cable and embedded processor
Serial data lead
IP68 Transit case with DuPont Velco internal case
** The Trimble GeoXT is shown for illustration only …
The following is a short list of accessories for the SonarMite …
SonarMite WinCE software c/w SonarVista software for PC
SonarMite WinXP software c/w SonarVista software for PC
GPS power/data lead adaptor
Aluminium shoe to connect transducer to detail pole

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INSTALLATION & USE
This chapter describes how the SonarMite Portable Echo Sounder would normally be
installed and used. There are three typical ways in which the device can be used for
hydrographic surveying applications, either as a „Dumb‟ sounder connected via a
serial cable/Bluetooth Link to a PC running data logging and display software, or as a
„Logging‟ sounder in which all depths are internally time tagged and stored. The third
option is to use both modes and use the serial output data for real time processing and
the stored data for post-processing applications.
Switching the System On
To turn the system on the user ensures the system is fully charged then connects the
transducer to the „TXR‟ connector on the front panel, the Red LED alongside the
connector will flash indicating connection and battery charge status.
Data Collection Techniques
When not used as a „Dumb‟ echo sounder in conjunction with a data logging package
the SonarMite can be used in conjunction with the following data types to create full
XYZ hydrographic data using the SonarVista software package….
Total Station XYZ data plus Time
XYZ data from RTKGPS plus Time
XY data from DGPS plus Tide plus Time
Range and Bearing from hand held laser plus Tide plus Time
Simple event marking past known position markers
The basis on which all data correlation is achieved is internal time base, so
particularly when using the SonarMite with GPS data the clocks should be
synchronised to GPS time (UTC).
Barchecking
The SonarMite default Speed of Sound in Water(SoS) setting is 1500m/second,
facilities to vary this have been provided in the calibration or in post processing. In
practice this velocity value can vary due to several factors …
Water Temperature
Water Salinity
Water Turbidity
All of the above factors vary the density of the water in some way and effect the „time
of flight‟ of a pulse of ultrasound in water and hence the depth calculated from this
time by the SonarMite. The user can either measure the speed of sound in water by
taking velocity profiles using a dedicated velocity measuring device or can use the
SonarMite static in a known depth over a flat, firm base and the compare the
measured value with the known depth. The difference in Sound Velocity between

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warm fresh water and cold salt water is about +/-30m/Second which represents a
change of depth of +/-2%, this must be viewed in context with typical depths of the
survey, if a typical depth is 10m then the error could be about 20cm. The Sound
Velocity setting is the largest source of measurement error when care is not
taken in setting it correctly.
Internal Battery Charging
The SonarMite is fitted with an internal sealed Nickel Metal Hydride battery which
provides 1.5Ahr @ 10vDC and a mains powered battery charger capable of bulk and
float charging to give the most efficient battery cycle. The user should avoid running
the SonarMite until the batteries are completely flat as there will be a high risk of both
data loss and permanent damage to the batteries. The charger will illuminate
CONSTANT RED when bulk charging and FLASHING YELLOW when charged,
the charger illustrated may change if a local mains variant is required.
DISCHARGE
CHARGE(on)
POWER(on)
READY(flashing)
CHARGE SEQUENCE
1
MEASURE BATTERY
CHARGE
POWER
READY
DISCHARGE
CHARGE(on)
POWER(on)
2
CHARGE
CHARGE
POWER
READY
DISCHARGE
POWER(on)
READY(flashing)
3
FINISHED
CHARGE
POWER
READY
DISCHARGE
POWER(on)
READY(flashing)
2
FINISHED
CHARGE
POWER
READY
DISCHARGE
DISCHARGE(on)
POWER(on)
1
DISCHARGE BATTERY
CHARGE
POWER
READY
DISCHARGE SEQUENCE
WARNING - Only the correct charger should be used with the SonarMite

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Reverse Voltage Protection
The SonarMite is protected from reverse connection or direct short circuit by an
internal 1.0Amp thermal fuse. If the fuse is tripped then the system will need to be
disconnected for 1 minute for the fuse to cool down and reset itself.
Weatherproofing
The SonarMite has been designed to conform to the IP67 waterproofing standard, this
benchmark describes equipment which can withstand a light spray of water from a
hose for a short period of time, it does not imply the device is suitable for immersion
in any depth of water or exposed to prolonged harsh weather conditions. The
weatherproofing also assumes the connectors or cover caps are fully screwed on to
their rubber sealing rings. The weatherproofing does not apply to certain components
which are by definition not designed for outdoor use such as the mains battery charger
and D9 serial cable connectors.

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DEPTH TRANSDUCER
The SonarMite system uses a „boat‟ shaped transducer in a „knock off‟ fitting for
fixing to the transom of a light boat or more commonly in a temporary mounting
using a survey detail pole.
Hydrodynamic shape provides vertical sound beam orientation on hull
deadrise angles up to 30
Reversible wedge allows mounting to transom angles from 2 to 22
Integral release bracket protects against impact damage, mounts with 3 screws,
and provides 12 mm of vertical adjustment
Chemical and impact resistant plastic housing
Designed to meet CE requirements
Shielded piezoceramic element for noise free echo sounder display
Standard cable length: 7.6 m (25‟)
Transom Mounting Transducer
Transducer Mounting
When mounting the transducers the following points should be taken into
consideration …
How near to the Metacentre of the boat is the transducer
Is any turbulence generated around or in front of the transducer when moving
Is the turbulence from the propellers in the field of view of the transducer
The only important consideration in mounting is that the transducer is always in the
water and that the transducer does not represent an obstacle when the boat is used at

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higher speeds (i.e getting to the survey location). If at all possible mounting the
transducer directly below the positioning antenna reduces the calculation of X/Y
offset to zero.
Example Transducer Mountings
Typical rubber boat mounting
Avoid Stressing Transducers
The Active Transducers include piezoelectric elements which are embedded within a
resin compound. If the user has to fabricate a custom mounting for the transducer (a
very common requirement given the vast permutations of boats in which surveys are
performed) avoid using a fixing technique that causes physical stress in the transducer
body as this will change the resonant properties of the device and effect its depth
measuring accuracy.