Sonar's come in three varieties. Sounders that measure the
distance to the bottom like Tritech's MicroSounder for $3,069.
Scanning sonars which sweep from side to side to reveal the terrain
ahead or in 360 degees like a weather radar to display everything
surrounding the ROV like Fisher's Scan 360 for $7000, and finally
Side Scan with displays the ocean floor to boths sides as it is
towed behind a boat. A low end side scan sonar like SportScan will
cost $5000. All together the sounder, scanning sonar, and side
scan sonar would cost a over $15,0000.
The idea we want to explore is adapting off the fish finder
technology for deep water exploration. In the US, recreational
fishing is a multi-billion dollar industry, and that money has
driven Humminbird and Lowrance the top two makers of fish finders to
radically improve their equipment of the years so that both now
offer all three sonar technologies as part of their product lines.
This resource has been ignored by the science and hobby ROV
communities because this equipment typically has relatively short
cables distances between the transducer which sits in the water and
the display console that interprets the signal from the transducer
and displays for the angler. However Lowrance opted for a
three component system. The transducer connects to a black box
where the signal is processed and then transmitted via common
Ethernet to one or more display terminals. This opens the door
for placing the transducer on an ROV and the black box inside the
ROV. The Ethernet signal can then be carried over 1K on a a single
23 awg twisted pair using VDSL2.
SpotlightScan transducer & Ethernet SonarHub
Width 7.1 in (180 mm), Height 2.2 in (57 mm)
Weight 1.5 lbs, Power 9-32 vDC min-max
Max .8A at 13.8 v
Sonar Hub Specs pdf
Lowrance offers two options for the transducers - the
StructureScan which is a side scan transducer and the SpotlightScan
which is a scanning sonar. The SpotlightScan transducer is dual
frequency 455 khz for 150 ft range and 800khz for more detail under
100ft. The SpotlightScan is ideal for approaching a target when it's
approximate location is known. StructureScan is more capable for
covering a search grid. The specifications for this project calls
for visually inspecting a target that was located by a separate side
scan unit, so StructureScan will best fulfill the requirement.
The SonarHub works with both units but only one transducer can be
connected to the SonarHub, as the SpotlightScan six conductor
twisted paired cable from the
transducer splits and connects to both transducer ports on the SonarHub. To operate both StructurScan and SpotlightScan at the same
time requires two SonarHubs. Alternatively the StructureScan
transducer could be supported by an LLS-2 which is the predecessor
to the SonarHub.
The SonarHub would be housed inside the ROV and connect to the ROV's
Ethernet network via a 10/100 Ethernet switch along with four full
HD IP cameras and a VDSL2 transceiver that connect to the surfice
vessel. Top side, the receiving VDSL2 transceiver would connect to
second 10/100 Ethernet switch with connections to the controlling
laptop computer and the Lawrence Gen2 display unit.
Sonar Hub Specs pdf
HDS-7 Gen2 Touch $1000
Width 8.44", Depth 3.24", Height 5.76"
12 W (0.9 A @ 13 V DC)
The SpotlightScan transducer which will be made available in February
2014 together with the Sonar hub sells for about $1000
An HDS-5 ( 5 inch ) Gen 2 display cost $650. So for less
than $2000 we have a scanning sonar.
Larger displays with touch screens are available. The HDS-7 Gen2
Touch , is a 7 inch display for $1000.
For $200, a GoFree Wireless module can be added to any HDS Gen 2 or
Touch display to allows the screen view to be shared with multiple
iPad tablets. When connected to a HDS Gen2 Touch devices the iPad
can both view and control.
Lowrance GoFree WiFi shares the display with
iPad or Galaxy tablets. $200
NMEA 2000 trolling motor foot control sensor
NMEA 2000 Starter Kit $70
Numerous modifications and test will need make to transition the
equipment to a deep sea ROV but a successful effort will mean the
proliferation of sonar exploration equipment leading to the
discovery and survey of more of the worlds ancient archeology before
it is destroyed by the forces of nature and bottom trawling.
The SpotlightScan sonar is designed to mount onto a trolling motor
which is rotated by a foot pedal. In order to process the image from
the transducer the display unit also requires input from a position
sensor mounted on the foot controller. This position sensor is
connected to the display by a NMEA 2000 network. Rotating the
transducer without the position sensor or moving the vessel forward
will not produce a useable image. The trolling motor foot control
sensor must be actuated proportional to movement of the
SpotlightScan transducer. The boat can be making headway at less
than 2 knots while the transducer is being swept, but the movement
will degrade the image. Sweeping the transducer slower produces
higher quality images. A 30 degree sweep should be done in about 6
seconds. The SpotlightScan transducer is composed of two narrow
vertical beams separated by a 30 degrees, so a 30 degrees rotation
of the transducer covers 60 degrees of the bottom. At a range of 100
feet the 60 degree cone will cover a 100 foot wide swath of the
Because the trolling motor foot control sensor utilizes NMEA 2000
it's functions is best replicated on the surface vessel, near the
display console. This can be done using Arduino controllers. One
Ethernet connected Arduino on the ROV will use a stepper motor
controller to rotate the SpotScan transducer with an oil compensated
Nema 17 stepper motor, while another Arduino controller near the HDS
touch console mimics the movement of the foot pedal either with a
signal from an analog output port or by mechanically moving the foot
control sensor with a servo that operates in proper proportion with
the rotation of the stepper motor moving the transducer.
Cable from the transducer is 22 AWG twisted pair for each channel.
Each channel is wrapped in its own shield. There is also an outer
shield for the cable.
|Wiring Lowrance Ethernet to standard Cat5
||Position from left in Cat5 connector
with the clip away from you.
Lowrance Ethernet Pinout, Back of plug view.
Drew Morgan used PCB Artist available from
www.4pcb.com to generate a two
sided PCB board that when cut in half will replace the cable plug in
port cards provided with the Lowrance SonarHub. The new cards
have a low profile that will fit inside the SornarHub housing and
make it easy to solder the wiring harness directly to card.
rence - Navico Customer Service line at 1-800-628-4487
11068-001 Wifi works with HDS-5 ipad
Marine Sonic custom built side scan sonar for AUV/ROV
installations but the cost run between 25 to 35K.
Fisher Scan 650
S06377 MicroSounder, 750m echo sounder $3,069
Other Sonar Sources: