ohmex SONARMITE DFX dual beam User manual

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SONARMITE v1.20
DFX dual beam
PORTABLE BLUETOOTH ECHO SOUNDER
Ohmex is a company formed to manufacture and distribute products designed by Lymetree Associates established in 1982 founded
on technological innovation and design. The designer prides themselves 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 on a standard PC, SONARLITE, 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. SONARMITE the first portable
Bluetooth echo sounder based on WinSTRUMENTATION - The integration of Instrumentation, Wireless networks and modern
portable computer equipment.

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Contents
INTRODUCTION.............................................................................................................................................4
Is Dual Frequency required ? .................................................................................................................... 5
Can mud thickness can be measured with Dual Frequency ? .................................................................. 5
Typical Use of the Equipment...................................................................................................................5
Equipment Supplied.................................................................................................................................. 6
Accessories................................................................................................................................................ 7
INSTALLATION & USE ....................................................................................................................................8
Switching the System On ..........................................................................................................................8
Data Collection Techniques ......................................................................................................................8
Sound Velocity Settings ............................................................................................................................9
Reverse Voltage Protection ......................................................................................................................9
Weatherproofing ......................................................................................................................................9
DEPTH TRANSDUCER...................................................................................................................................10
Transducer Mounting .............................................................................................................................10
Avoid Stressing Transducers ...................................................................................................................11
BLUETOOTH INTERFACE..............................................................................................................................12
BlueTooth ID/Password code..................................................................................................................12
Bluetooth™ Serial Port Profile ................................................................................................................12
Features ..................................................................................................................................................12
Bluetooth - actual range of the device. ..................................................................................................13
Connecting to another Bluetooth™ PC/PDA...........................................................................................13
SERIAL CABLE INTERFACE............................................................................................................................14
Typical Windows HyperTerminal settings...............................................................................................15
CONNECTIONS ............................................................................................................................................16
‘PC’ or Computer connection..................................................................................................................16
‘Transducer’ connection .........................................................................................................................16
APPENDIX....................................................................................................................................................17
SonarMite Settings..................................................................................................................................17
Flash Memory .........................................................................................................................................17

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DFX version Commands ..........................................................................................................................17
☺(^H)elp.............................................................................................................................................17
Memory Operations................................................................................................................................17
☺(^R)eset ..........................................................................................................................................17
☺(^L)oad ...........................................................................................................................................18
☺(^S)ave............................................................................................................................................18
General Operations.................................................................................................................................18
☺(?) Query format ............................................................................................................................18
☺(^F)ormat .......................................................................................................................................19
☺(^V)ersion.......................................................................................................................................23
☺(^I)d................................................................................................................................................23
☺(^U)p ..............................................................................................................................................23
☺(^D)own..........................................................................................................................................23
☺(^C)lear...........................................................................................................................................23
☺(^B).................................................................................................................................................23
Transducer Specification.........................................................................................................................24
Transducer Dimensions...........................................................................................................................25
System Specification ...................................................................................................................................25
WIRING DIAGRAMS.................................................................................................................................26

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INTRODUCTION
The SonarMite Echo Sounder was the result of nearly two years research and development to
further extend the boundaries of shallow water hydrographic surveying equipment. The
introduction by Ohmex of the SonarMite, 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 DFX 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 100m
away from the instrument.
SonarMite DFX logging software

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The SonarMite DFX instrument uses the same 'Smart' integrated transducer technology used in
previous systems, in addition to highly reliable bottom tracking algorithms using DSP techniques
the system also outputs a water temperature measurements with associated with every depth
measurement made. The popular SonarW7 software has been updated to the latest Windows
versions. 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 and Tablet systems running the
Windows operating system.
Is Dual Frequency required ?
Dual frequency echo sounders were originally designed for use by sea going vessels to give
reliable depths in deep water situations (low frequency) and more accurate navigation within
shallow areas (high frequency). Low frequency is of little use in shallow hydrographic surveys
Physical accuracy is outside IHO specifications
Power consumption prohibits true portable use
Minimum depth possible outside survey requirements
However, Dual Frequency measurements may be specified as part of a survey contract as it is a
good gross check on high frequency performace (does not reflect from small objects in the water
column) and it will indicate areas of soft bottom.
Can mud thickness can be measured with Dual Frequency ?
The residual difference between low and high frequency shown on an echogram gives the
impression that mud thickness can be measured. In fact the trace does give an impression of soft
sediment, however, in most sounders this is just the difference in reflected energy as a result of
simple penetration of higher power low frequency signals plotted against the low power high
frequency returns.
To measure mud thickness and avoid litigation on wrong results the surveyor should use
equipment specifically designed for geophysical measurements such as a sub-bottom profiler,
penetrometer, seismograph or a simple bottom sample grab.
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 minimum water depth below the

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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.
200/30 KHz Active Transducer
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 I/O, none of the
EMC problems associated with conventional analogue sonar 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 be „turned on‟by cable connection rather than using a switch.
Cables to the device can be connected simultaneously (e.g. Transducer on port 1 and Serial Data
Cable on Port 2).
Equipment Supplied
The SonarMite DFX is supplied as standard with the following list of equipment …
•SonarMite DFX main processor unit c/w Bluetooth Antenna
•„Smart‟ DF depth transducer c/w 5m cable and embedded processor
•Serial data lead
•IP68 rugged plastic Transit case
•SonarW7 post process/import/export software

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Accessories
The following is a short list of accessories for the SonarMite DFX …
•SonarMite DFX Windows Mobile PDA software
•SonarMite DFX Windows PC/Tablet software
•USB serial data lead
•Aluminium fitting to connect transducer to detail pole
•Portable internal NiMh battery pack and charger.
SonarMite DFX dual beam echo sounder
The SonarMite DFX is a compact, portable, low power system for use in shallow water
hydrographic surveys, it's small size and low power requirements make the system easy to
deploy and transport to remote or inaccessible sites. The SonarMite DFX is a dual beam echo
sounder providing a wider range of solutions for surveyors working in shallow water
hydrographic surveying.

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INSTALLATION & USE
This chapter describes how the SonarMite Portable Echo Sounder would normally be installed
and used. The typical way in which the device can be used for hydrographic surveying
applications, is as a „Dumb‟ echo sounder connected via a serial cable/Bluetooth Link to a PC or
PDA running data logging and display software. Another option is to use both data streams with
the serial output data for real time processing and the parallel Bluetooth output for graphic depth
display.
Typical bow transducer mounting
Switching the System On
To turn the system on the user ensures the system is connected to a battery then connect the
transducer to the „Txr‟ connector on the front panel, the green LED alongside the Bluetooth
antenna will then illuminate.
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 SonarW7 software package….
•Total Station XYZ data plus Time
•XYZ data from RTK GPS plus Time
•XY data from DGPS plus Tide plus Time

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•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 data logger clock should be synchronized to GPS time
(UTC).
Sound Velocity Settings
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 over a known depth to a flat,
firm base and then compare the measured value with the known depth. The difference in Sound
Velocity between 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.
Reverse Voltage Protection
The SonarMite DFX is protected from reverse connection or direct short circuit by an internal
diode and 1 Amp 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 IP65 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 D9 serial or USB cable connectors.

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DEPTH TRANSDUCER
The SonarMite DFX system uses a „boat‟ shaped transducer in a three bolt mount fitting for
fixing to an outrigger of a light boat or more commonly in a temporary mounting using a survey
detail pole. The transducer includes a unique processor and is not the same device as the
commercially available transducers.
•Hydrodynamic shape provides vertical sound beam orientation
•Chemical and impact resistant plastic resin housing
•Designed to meet CE requirements
•Shielded piezoceramic element for noise free echo sounder display
•Standard minimum cable length: 5.0 m (16 feet)
Transom Mounting Transducer
Transducer Mounting
Typical bow transducer mounting