Category Archives: Acoustics & Sonar

U.S. deep-sea sub “Nereus” lost in Kermadec Trench

A deep-sea research sub has been lost in Kermadec Trench, one of the ocean’s deepest spots, which lies northeast of New Zealand, media reports said Tuesday.

The unmanned robotic vessel, called Nereus, went missing on Saturday while exploring the Kermadec Trench. It was a flagship ocean explorer for the U.S. science community.

Surface debris was found, suggesting the 8 million dollar sub suffered a catastrophic implosion as a result of the immense pressures when it was operating some 10km down. The deep trench has pressures of about 16,000 pounds per square inch(psi).

“Nereus helped us explore places we have never seen before and ask questions we never thought to ask,” said biologist Timothy Shank from the Woods Hole Oceanographic Institution, which managed the sub.

The robot was built in 2008 and could operate in an autonomous mode or remotely controlled via a tether to a support ship to explore the Earth’s deepest oceanic trenches. The team is now collecting surface debris in hopes of revealing more about the implosion.

Read more here

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CNN consults ATIcourses: Our instructor Vincent Capone gives interview!

ATI’s instructors are world-class experts. They are the best in the business, averaging 25 to 35 years of experience, and are carefully selected for their ability to explain advanced technology in a readily understandable manner.

ATIcourses was contacted by CNN to gain insight on the technology being employed in search for Malaysia Flight 370 that went down in Indian Ocean.  We are very proud that our instructor for Design, Operation and Data Analysis of Side Scan Sonar Systems course, was recently interviewed by CNN.  You can watch the video by following this link.

We are planning to present this course in fall of 2014.  If you are interested in attending, please sent us an email to

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Will passenger remains from missing Malaysia Airlines Flight 370 ever be found?

Navy personnel on board a P-8I aircraft during a search operation for the missing Malaysia Airlines flight MH370 aircraft in the southern Indian Ocean.

As the search for the missing Malaysia jet continues, the likelihood that remains of the plane’s 239 passengers will be found dwindles, according to aviation experts.

David Learmont, operations and safety editor at Flight International magazine, told NBC News while it’s not out of the realm of possibility, each passing day makes it more unlikely that remains or even personal effects from those on Malaysia Airlines Flight 370 will be found. The plane disappeared March 8 and, despite several promising leads, no wreckage or debris has been found.

Among the problems, Learmont said, is the vast search area and the unknowns related to where the plane went down, things that are different than the 2009 crash of Air France 447. In that crash, searchers were able to find remains two years after the plane went down in the Atlantic Ocean off the coast of Brazil.

“MH370 is a different ball game,” Learmont said. “We know nothing.”

A robotic submarine searching for the wreckage completed its first full 16-hour mission Wednesday after two previous aborted missions. The Bluefin-21 autonomous underwater vehicle has searched about 35 square miles in its three trips.

So far, the data shows no sign of the plane, officials said, adding it could take up to two months for the submarine to scour the 250-plus mile search area.

DNA could be used to identify remains


The ocean floor where the jetliner is believed to have gone down is silty, Learmont said, making recovery even more difficult but keeping some animals away from the area.

“Anything heavy — engine parts, wing spars — may sink in, in which case … we may not be able to ‘see’ anything,” Learmont said.

If even fragments of remains are ever found, experts will be able to use DNA and forensics to determine whom they belong to. First, however, an unmanned vehicle would have to haul the wreckage and any remains to the surface.

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Malaysia Airlines Flight 370: The result of Bluefin-21’s first foray? Nothing of interest.

Time to try this again. The first deployment of an underwater vehicle to hunt for Malaysia Airlines Flight 370 was aborted early, sending the drone back to the surface 10 hours before expected. Search officials analyzed data from the Bluefin-21’s six hours underwater, and found no objects of interest, the U.S. Navy said Tuesday.

Read more here.

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Malaysia Airlines MH370: Should $3bn. be invested to map the ocean floor?

It has been over a month since Malaysia Airlines MH370 went down and the search still continues.  The biggest problem that the searchers face is poor maps on the ocean floor (see below).

The majority of the information comes from satellites that infer the shape of the ocean bottom from the shape of the water surface above.  However, satellite are not flying a mission specifically dedicated to the task of mapping the ocean floor.  A mission like that is estimated to cost $100m and none of the governments are willing to commit to this endeavor.  We know more about the surface of Saturn of Jupiter than our own waters.  The best way to map the ocean floor is through  a modern swath-mapping echosounder system.  It would take 20 dedicated ships 10 years to complete this task. This could be achieved for about $3bn.  It sounds like a lot but a lot of disasters could be avoided.  Think of the  nuclear submarine USS San Francisco that crashed into  a seamount in 2005.

The USS San Francisco hit a seamount inadequately recorded on navy charts

In addition, more accurate mapping is also important for fisheries management and conservation, because it’s around the underwater mountains that wildlife tends to congregate. Each seamount is a biodiversity hotspot.

What are  your thoughts on this?  Should we explore our own planet first or put all the resources into exploration of other planets?  Please comment below…

Read more here.

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Malaysia Air Flight 370: Two More Pings Received Yesterday

ATIcourses offers a variety of courses on technology currently employed in search for Malaysia Air Flight 370.

The search teams looking for the wreckage of Malaysia Air Flight 370 believe they have heard a total of four pings from the “black boxes” in the last few days — two of which were received yesterday. The signals came from the narrowing search area off of Australia’s northwest coast, on frequencies consistent with those of commercial-aircraft flight recorders. After more than a month, though, time is running out on locating them through their beacon transmissions.

Read more here.

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Malaysia Airlines flight MH370’s black-box pingers. Technical acoustic information that may be useful to reporters and researchers

The mystery of the missing Malaysia Airline flight MH370 is closer to being solved as authorities have revealed that they have tracked the final unexplained signal emitted by the jet, to the same point in the Indian Ocean, where the jet was believed to have crashed. Time will tell whether this is a definitive lead or a false alarm. We all hope it is the beginning to a successful answer.

Calling the latest development a promising lead, retired Air Chief Marshal Angus Houston, who is leading the search, said that an Australian navy ship had detected two sets of pulse signals that sounded just like an emergency locator beacon.

While the first set was heard on Saturday and lasted for two hours and 20 minutes, the Ocean Shield ship then lost contact with the “pings” but turned around and later heard further signals for 13 minutes, the Sydney Morning Herald reported.

However, the ship lost contact again and has been trying to relocate the signals.

Houston said that in the search so far it is probably the best information that the team has had, adding that the search team is encouraged that it is very close to where it needs to be.

He added that he would want more confirmation before he could say ‘this is it’.

Here is a list of the equipment that is being employed by the searchers.
If you find this information useful, please mention ATICourses.if you use the materials that we have gathered. ATIcourses has a strong set of courses in underwater acoustics and oceanography that provide additional information. Some of our instructors are willing to provide more in-depth information to reporters who are actively covering the Malaysian flight MH370 investigation to provide accurate, in-depth information. Contact us at

More info

1. Beacon Black Box Locator Acoustic 37.5 KHz Pingers

An underwater locator beacon (ULB) or underwater acoustic beacon, also known informally as a pinger, is a device fitted to aviation flight recorders such as the cockpit voice recorder (CVR) and flight data recorder (FDR). ULBs are also sometimes required to be attached directly to an aircraft fuselage. ULBs are triggered by water immersion; most emit an ultrasonic 10ms pulse once per second at 37.5 kHz ± 1kHz.
Maximum detection range
A 37.5 kHz (160.5 dB re 1 μPa) pinger can be detectable 1–2 kilometres (0.62–1.24 mi) from the surface in normal conditions and 4–5 kilometres (2.5–3.1 mi) in good conditions. A 37.5 kHz (180 dB re 1 μPa) transponder pinger can be detected 4–5 kilometres (2.5–3.1 mi) in normal conditions and 6–7 kilometres (3.7–4.3 mi) in good conditions.
• Operating Frequency: 37.5 kHz  ± 1 kHz (Doppler can shift the measured frequency)
• Operating Depth: Surface to 20,000 feet (6100 m or 3.33 nmi)
• Pulse Length: Not less than 9 milliseconds (10 millisecond nominal)
• Pulse Repetition Rate: Not less than 0.9 pulse per second (1 pulse per second nominal)
• Acoustic Output, Initial: 1060 dynes/cm2rms pressure at 1 meter (160.5 dB re 1 UPa/ meter)
• Acoustic Output, After 30 days: 700 dynes/cm2rms pressure at 1 meter (157.0 dB re 1 UPa/meter or about 70 % of the nominal range as it degrades)
• Radiation Pattern: Rated output over 80 percent of sphere, near omni-directional
• Size: 1.3″ diameter x 4″ long (DK100/DK120)
• 1.3″ diameter x 2.97″ long (DK130/DK140)
• Weight: Less than 7 oz (including battery) (DK100/DK120)
• Less than 4.9 oz (including battery)(DK130/DK140)
• Power Source: Lithium Battery
• Expected range: about 2 nmi slant range radius from source for 37.5 KHz

Expected Transmission Loss at 37.5 Khz assuming absorption of 4.2 dB per KIM plus spreading loss of 20 log R or 60 dB + 10 log r for R> 1000 meters

37.5 KHz ———————— 0.31 mi .62 mi 1.25 mi 3.25 mi 6.2 mi 10 mi 100 mi mi
Range in KM ———————— 0.5 1 2 5 10 16 160 KM

TL =20 log Rkm*1000+ alpha*Rkm 56.1 64.2 74.4 95.0 122.0 151.3 776.1 TL (dB)

TL =20 log Rkm*1000+ alpha*Rkm for RKM <1 Km 56.1 64.2 71.4 88.0 112.0 139.2 754.0 TL (dB) TL =60 +10*log Rkm+ alpha*Rkm for RKM.>1

2. Autonomous Underwater Vehicle – Bluefin-21 Search Vehicle


The Bluefin-21 is a highly modular autonomous underwater vehicle able to carry multiple sensors and payloads at once. It boasts a high energy capacity that enables extended operations even at the greatest depths. The Bluefin-21 has immense capability but is also flexible enough to operate from various ships of opportunity worldwide.

Depth Rating 14,763 ft (4,500 m)
Endurance 25 hours @ 3 knots with standard payload

EdgeTech 2200-M 120/410 kHz side scan sonar for search

Reson 7125 400 kHz multibeam echosounder for site mapping


3 Side Scan Sonar Option – EdgeTech 2200


The Full Spectrum chirp side scan sonar is a calibrated wide band digital FM sonar that provides quantitative and qualitative, high resolution, low-noise side scan imagery. It simultaneously transmits linearly swept FM pulses and the user may select the combination of these frequencies dual simultaneous as follows:


120/410 kHz, (most likely for Malaysia Airline Flight 370 Search)

75/410 kHz,

75/120 kHz or

300/600 kHz.


A Digital Signal Processor (DSP) in the Full Spectrum (FSDW) electronics on the AUV or ROV holds the two chirp waveforms to be transmitted.


ATI thinks the side scan frequency is likely to be 120/410 KHz which will give ranges of 250 m to 500m at 120 KHz and 130M to 200m at 400 Khz.


That will imply short detection ranges even for the 120 KHz sonar, say 250 – 500 m per side. The 410 KHz is then used at shorter range (130 – 200 m) to get a higher resolution image. The search pattern must overlap to leave no coverage holes, so the offsets in range between passes may be at most 90 percent of the assured range.


Expected Operational Ranges for the EdgeTech 2200- side scan sonar, depending on Water temperature and salinity. The absorption factor is estimated based on a model from Francois and Garrison, JASA 1982, and a depth of 50m. Absorption decrease slightly as the side scan is towed deeper. The range is to each side and the search rate is likely to be limited to 2.5 or 3.0 knots to keep the autonomous underwater vehicle (AUV) near the bottom on a long cable scope.

Quoted from


  • Freq : 120Khz, Range: 250 to 500m
  • Freq: 410kHz, Range: 130 to > 200m


  • Freq : 75kHz, Range: 700 to 800m. 1000m is possible at extreme depths and with special pulses
  • Freq : 270kHz, Range : 150 to 300m
  • Freq : 540kHz, Range: 100 to 150m
  • Freq : 850kHz, Range: 50 to 75m


4. SeaBat 7125 – Reson 7125 400 kHz multibeam echosounder


The fundamental acoustics with 400 kHz for high resolution, high density surveying which exceeds the most stringent of specifications, and 200kHz for greater range performance. The SeaBat 7125 can be installed on any platform from survey vessels to ROVs and AUVs down to 6000m water depth.


The 400 kHz multibeam echosounder is a multibeam mapping sonar. ATI would expect that it will need to be towed about 150 – 400 m off the bottom to get good signal to noise. It is likely used to map the wreckage after it has been found using the side scan sonar.


Then ATI expects some short range video to confirm and map the wreckage.


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