This is only a preview of the February 2010 issue of Silicon Chip. You can view 17 of the 104 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Items relevant to "An OBDII Interface For A Laptop Computer":
Items relevant to "A Milliohm Adaptor for Digital Multimeters":
Items relevant to "Internet Time Display Module For The WIB":
Items relevant to "A Multi-Function GPS Car Computer, Pt.2":
Items relevant to "Precision Temperature Logger & Controller, Pt.2":
Articles in this series:
Purchase a printed copy of this issue for $10.00. |
Australian innovation could be the key to
SAVING
the
WHALES
by
Ross Tester
18 Silicon Chip
Each year around the
world enormous numbers of
marine mammals are caught in
both commercial fishing nets and
the shark nets protecting our beaches.
Now an Australian company has come
up with a way to warn cetaceans –
dolphins, porpoises and soon whales –
away from nets and hopefully save many of
these magnificent creatures from becoming
what is euphemistically known as “by-catch”.
www.siliconchip.com.au
siliconchip.com.au
C
ommercial fishermen hate seeing whales, dolphins or porpoises entangled in their nets.
Fishermen would much rather large
mammals stay away from their trawl
nets. Unfortunately, the very fish
they are catching often attracts such
animals – and they end up as part of
the catch.
Apart from the damage to the nets
(and the down-time for necessary repairs and/or the cost of replacement),
a significant amount of their catch
can actually be eaten by the time the
mammal is freed, more likely dead
than alive.
World-wide, it is claimed that
around 300,000 of these creatures are
accidentally entangled and drowned
in commercial fishing nets.
Shark nets
As far as against protective shark
netting off popular beaches goes, the
arguments for and against drag on,
with plenty of heat on both sides.
While proponents point out the
effectiveness of shark nets in saving
humans from attack (for example,
there hasn’t been a fatal shark attack
off a Sydney ocean beach since nets
were first introduced in 1937, after
many attacks over previous years)
opponents consistently point out the
numbers of “other” marine animals
caught and usually killed by the nets.
Again, most of the time, it’s the
“emotive” marine mammals including
whales, dolphins and porpoises which
attract attention from both tabloid
media and some of the more alarmist
websites.
The Pinger
But now at least, dolphins and porpoises in particular have a guardian
angel in a Sunshine Coast (Qld) company called Fumunda Marine and its
cetacean warning device, commonly
known as the “Pinger”.
The small (46 x 152mm) and light
weight (210g) Fumunda Pinger is designed to be attached to a net. It emits
a 300ms pulse at 10kHz every four
seconds, with a sound pressure level
in water of 132dB.
This frequency was chosen for two
reasons: (a) it is known that dolphins
and porpoises can hear it.
More importantly, numerous independent scientific studies performed
around the world over the past twenty
years on different species and populasiliconchip.com.au
Director of Fumunda Marine, James Turner, shows his company’s “Pinger”
which has been reported to reduce by-catch by 80-95%. While the model he
holds is intended for dolphin and porpoise repelling on commercial fishing
nets, Fumunda are currently developing a Pinger specifically intended to reduce
whale entanglement in commercial fishing nets and beach shark nets.
tions of dolphins and porpoises have
shown that it has the longest trackrecord of any signal for reducing dolphin and porpoise by-catch.
Tests also confirm that Pingers are
over 90% effective in reducing dolphin and porpoise by-catch in commercial net fishing practices.
The Pinger has undergone extensive
testing at the US Navy’s Transducer
Evaluation Center (TRANSDEC) Un-
derwater Facility in San Diego, California which performs research, development, preproduction and acceptance
testing of underwater electro-acoustic
transducers for numerous Navy and
private party customers.
Inside the Pinger
While exact circuit details are a
closely-guarded secret, Fumunda’s
James Turner has revealed that it is
February 2010 19
to ping for about two minutes – again
confirming its operation.
Operation
A close-up of the commercial fishing Pinger, showing its tiny size relative to the
hand holding it. The two electrodes seen on the body are responsible for turning
the unit on when it is lowered into seawater.
controlled by a Pic micro, which sets
up the various timing circuitry to
initiate the short 10kHz discharge via
an inductor into a piezo transducer.
The result is the characteristic
“ping” (not unlike a submarine sonar)
which gave the unit its name. While
the unit can be heard operating in
air (in fact that, in conjunction with
oscilloscope waverforms, is how Fumunda’s quality control ensures they
are working correctly. Each is compared to a known standard to ensure
it is within specification).
The whole unit is potted in resin
and encased in a very strong, solid elliptical case, designed to slip through
the water with minimum drag on nets.
A great deal of attention was paid to
the design and manufacture of the case
– instead of being moulded or cast, the
cases are CNC machined from a solid
rod of a special co-polymer to tolerances not much more than 1 micron.
from the fishing or shark net to have
the battery replaced – as long as it is
out of the water, it can be achieved in
minutes.
Because it is audible to humans, no
special test gear is necessary to confirm
that the Pinger is working before it
goes back in the water. And when it is
removed from the water, it continues
The Pinger only starts operating
when it is immersed in seawater.
That’s the function of the two electrodes you can see in the above photo.
As everyone knows, sound travels
significantly better through water than
through air – by a factor of six times.
That’s why the SPL in water is a rather
staggering 132dB and is also another
reason why the targeted mammals can
hear it so well.
Incidentally, fish, sharks and other
marine animals do not have the same
sense of hearing that mammals do
(in fact most have none at all), so are
essentially undisturbed by the Pinger
– even when operating right next to
them.
A significant amount of by-catch
occurs at night when the nets are all
but invisible in the water (during the
day, they stand out much more).
What the Pinger does is acoustically
“illuminate” the net. It doesn’t so
much say “Danger, Will Robinson” as
say to the animal that there is “something” there to be wary of.
Many cetaceans navigate by eco-location. They learn that certain areas are
no-go zones which hopefully will keep
them safe from the nets with Pingers
on them. In some ways, the Pinger
operates like a fish finder, except that
Battery replacement
One end of the case is removable to
allow the user to replace the battery
(earlier devices had to be returned to
the manufacturer or agent to replace
the battery).
Even so, battery life is estimated at
two years, based on 12 hours per day
usage. The Pinger also doesn’t have the
disadvantage of having to be removed
20 Silicon Chip
This Pinger is “laced” into a commercial fishing net. The shape and material
of the Pinger case makes it offer minimal resistance in the water, minimising
any extra drag on the nets. Each Pinger can operate up to two years before the
battery needs to be changed – a task which can be undertaken on the deck of a
fishing boat quite quickly and easily.
siliconchip.com.au
in this case it is not looking for any echo from the fish.
Of course, while the Pinger is based on a lot of scientific
studies and observation of mammal behavior, it is still
based on theory.
If anecdotal evidence is any guide, the Pinger has proved
to be effective in reducing by-catch. But there is obviously
a long way to go and a lot more information to be gathered.
In Australia, there are around 1700 commercial fishing
licences. Fumunda believe it would take around 12,000
Pingers to cover the Australian fleet. But that is just Australia, where there is no legislation forcing such devices to
be used. That’s a pretty significant market.
But that pales into insignificance when compared to the
overseas market. It is enormous, especially now that much
of Europe is widely enforces their use under the European
Commission (EC) code 812/2004.
In the USA National Marine Fisheries Service (NMFS)
regulations enforces the use of Pingers in certain areas of
the commercial fishing industry.
The Pinger meets both of these codes and is now being
sold in both areas.
100 MHz MSO 8M Samples 14 bit
High Resolution Spectrum Analysis
Whale protection
We’ve concentrated on dolphins and porpoises in this
feature but arguably the most public outcry occurs when
a whale is caught in a net.
Various methods have been tried to keep whales away
from nets in the past, including playing the sound of a
killer whale underwater. But as recently as last October, a
juvenile humpback whale was caught in nets off the Gold
Coast while this technique was in use. Four humpbacks
were caught during 2009.
However, whales are known to respond to lower-frequency signals than other cretaceans so recently Fumunda
Marine started working with the Queensland Department
of Primary Industries and Fisheries to reduce the number
of migrating whales caught in shark nets along the east
coast of Australia
Approximately 12,000 whales travel up and down the
east coast each year. The team at Fumunda, like the New
South Wales and Queensland Departments of Primary
Industries want to reduce the number of incidental entanglements. On the west coast more than 17,000 Humpback
whales make the migration to the warmer northern waters
for breeding, having to navigate through thousands of lobster pots which are set everyday.
Fumunda marine believe whale Pingers could very easily
be deployed in clusters of lobster pots to reduce the risk
but have yet to convince the West Australian authorities.
The latest whale Pingers have been designed to operate at a much lower frequency – about 3kHz – which is
known to be audible to whales. As distinct from dolphin/
porpoise Pingers, the whale Pinger operates with a constant
frequency tone.
As well as being significantly smaller and lighter, making handling and fitting to the nets much easier, the new
whale Pingers will also be significantly more powerful
than the existing models,. They will be made using high
quality internal components and long-lasting replaceable
batteries, ensuring reliable performance.
The whale Pinger technology has applications globally
and the company hopes to work with other stakeholders to
further protect these wonderful marine mammals.
SC
siliconchip.com.au
High Resolution
Spectrum Analysis
Spectrum Graph zoom:
Capture a 50Mhz bandwidth with
50 Hz resolution. Zoom on any
point. Using the 14 bit ADC, you
get a -85 dB noise floor over the
whole bandwidth. Use the
hardware moving average filter to
further improve this.
Example:
Example
Capture 1.000 and 1.001 MHz
mixed signals. Display the signals
with 50 Mhz bandwidth. Intermod is
-80 dB!
Check out High Resolution
Spectrum Analysis on the
Examples page at
www.cleverscope.com
+ Two mixed signal triggers
+ Protocol decoding
+ Spectrum analysis
+ Symbolic maths
+ Custom units
+ Copy & paste
+ Signal generator
+ USB or Ethernet
+ 4 or 8M samples storage
+ 100 MHz sampling
+ Dual 10, 12 or 14 bit ADC
+ Ext Trigger, 8 Digital Inputs
+ 1 MSa/sec charting
Distributors:
Grantronics - Sydney
www.grantronics.com
02 9896 7150
Trio Smartcal
www.triosmartcal.com.au
1300 853 407
LE Boughen – Queensland
www.boughen.com.au
1800 068 663
www.cleverscope.com
February 2010 21
|