I have been thinking about the MH370 incident and trying to make sense of the press releases and press conferences. Unfortunately the search coordinator and spokesperson (Angus Houston) appears to be essentially ignorant of the technology involved. His explanations are just technobabble.
"The advice from the manufacturer is that 33 kHz is, or 33.2 kHz, is quite credible. The Air France locator battery from five years ago was 34 kHz. So, what happens is, there is a change with the pressure on the ocean floor and the age of the particular batteries, the capacitance can change and you get changes in the transmission level."
"The Air France locator battery from five years ago was 34 kHz."
No Angus, a battery doesn't produce a frequency, it produces voltage and current. In any case, the blackboxes were not found until two years after the crash, and the frequency was only determined after reanalysing the sonar records of a French submarine long after the event.
"While the Brazilian Navy removed the first major wreckage and two bodies from the sea within five days of the accident, the BEA's (Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile) initial investigation was hampered because the aircraft's black boxes were not recovered from the ocean floor until May 2011, nearly two years later."
"The advice from the manufacturer is that 33 kHz is, or 33.2 kHz, is quite credible."
I wonder if the AF447 investigators actually tested the Underwater Locator Beacon (ULB) after it was retrieved (after replacing its battery, of course). In fact, I would suggest that the MH370 investigators obtain other ULBs from Malaysia Airlines, preferably from the same batch, or at least the same model and vintage, and then subject them to some simple tests of their own, without relying on the information from the manufacturer (Dukane Seacom). Specifically, I would remove the existing battery (3V lithium) and replace it with a variable DC power source, say 0V - 3.6V. Then record the emitted frequencies and sound pressure levels. That should tell us whether 33.2kHz is "credible".
Another idea would be to use Bluefin (Autonomous Underwater Vehicle) to take a few of these ULBs to the bottom of the ocean and perform some simple tests.
"there is a change with the pressure on the ocean floor".
The manufacturer specifies that its ULB is certified for correct operation at a depth of 20,000 feet (approximately 6000 metres). Apparently this is a requirement of the relevant standard (TSO-C121). Therefore, it makes no sense to say that a depth of 4500m is responsible for the reported frequency deviation.
"you get changes in the transmission level"
"Transmission level" and "frequency" are not the same thing. The first relates to the amplitude, ie strength, of the signal, not its frequency. A weak battery will undoubtedly result in a reduced transmission level, but I find it difficult to understand how it would affect the frequency.
"the capacitance can change"
I would have thought that a ULB that sells for upwards of $1500 would have high quality components with negligible drift. In applications where temperature and frequency stability are paramount, a designer would specify a capacitor with a zero temperature coefficient and negligible leakage. For example, an NPO ceramic capacitor would have such characteristics. A frequency of 33.2kHz represents an 11.5% deviation from the specification. A $5 wrist watch (with a 32.768 kHz tuning fork crystal) can keep time with an accuracy of 10 parts per million, so why can't a $2K piece of avionics do as well as that?
Why does the 37.5kHz beacon have a tolerance of +/- 1kHz? That's about +/- 3%. What are they using for a clock source? I doubt that they would be using a quartz crystal, as these will shatter when subjected to relatively minor impacts. Could they be using a ceramic resonator, or are these also prone to shattering? Are they using a simple RC arrangement, and is this why the tolerance is so wide?
If the frequency of the beacon has in fact been reduced to 33.2kHz, then how has this affected the pulse width (10ms) and separation between pulses (1.1 second)? If the circuit is timed from a single clock source, then one would expect that the other two parameters would have drifted from the spec in exactly the same proportion. Is the separation between pulses now 1.25 sec, or has it remained at 1.1 sec? Is the pulse width now 11.5 msec? ISTR that Angus Houston mentioned 1.1 second as the pulse separation, so what is happening here? Is the ULB just some cheap RadioShack kit stuffed inside an expensive pressure vessel?
rockylizard said
10:33 AM Apr 14, 2014
Gday...
Thanks Dorian
Ya know, I actually read ALL that. Unfortunately, I still don't know anything more about a "black box/beacon/thingy" or anything that you were talking about.
But at least you attempted to illuminate the rest of us. Perhaps you should send this in an email to Angus.
Cheers - John
native pepper said
12:34 PM Apr 14, 2014
These black boxers are pretty old technology, could be wrong, but believe they are still using the same design since the 1980's and the reason the batteries don't last and the signals are not really designed for deep water operation.
Between the surface and 4500m to the bottom, there are many thermal, tide, current layers and columns of water with varying temperatures, salinity, density and atmospherics pressures. These have a big bearing on signal strength and frequency, plus signal can be diverted by these phenomena. When you consider where this is all taking place and look at the dynamics of the southern oscillation index of the souther ocean and its interaction with the Indian ocean. it's easy to see why they are having such trouble with firmly locating exactly where the signals are coming from at such great depth and pressure.
KFT said
04:16 PM Apr 14, 2014
NP if I remember correctly submarines used to use those thermal layers to hide from sonar so a black box should have no problem.
maybe they should be using sub hunters to look for what is left of the aircraft.
Operating Frequency ... 37.5 kHz ± 1 kHz
Operating Depth ... Surface to 20,000 feet (6096 meters)
Pulse Length ... 10 milliseconds + 10%
Pulse Repetition Rate ... Not less than 0.9 Pulse/Sec
Operating Life ... 30 days (minimum)
Battery Life In Beacon ... 6 Years
Acoustic Output, Initial ... 1060 dynes/cm2 rms pressure at 1 meter (160.5dB)
Acoustic Output After 30 Days ... 700 dynes/cm2 rms pressure at 1 meter (157.0dB)
Operating Temperature Range ... +28°F (-2.2°C) to +100°F (+37.8°C)
Actuation ... Fresh or salt water
Radiation Pattern ... Rated output over 80 percent of sphere
Size ... 1.30 inches (3.30 cm) diameter x 3.92 inches (9.95 cm) long (less mount)
Weight, Beacon ... 6.7 ounces (190 grams)
Weight, N30A26B Mount ... 6 ounces (170 grams)
Weight, N30A21A Mount ... 3 ounces (85 grams)
Storage Temperature Range ... -65°F (-54°C) to 160°F (71°C) - without battery
1.2.4. ENVIRONMENTAL TEST. The beacon complies with the preceding operational performance standards after being subjected to environmental tests specified in FAA TSO-C121.
"The printed circuit board assembly generates all the necessary logic functions to produce a pulse with the desired characteristics. The pulse is then transformed from a CMOS level square wave to a much larger 37.5 kHz sinusoidal pulse by a transformer. The output of the transformer drives the urethane-encapsulated transducer, which propagates through the housing in the form of a tuned 37.5 kHz acoustic signal."
"The device also provides stable frequency operation without a crystal-controlled oscillator over a wide range of source voltages."
It appears that this design uses two separate clocks, one for the beacon frequency, and the other for the pulse rate and duration. The clocks are derived by selecting appropriate resistor and capacitor combinations.
"Oscillator 24 [for the beacon frequency] consists of a monolithic, linear, dual-in-line integrated circuit 48, tuning resistors 44 and 46, and tuning capacitor 50. Resistors 44 and 46 and capacitor 50 determine the oscillator frequency.
Pulse generator 28 [for pulse rate and duration] additionally uses a monolithic, linear, dual-in-line package integrated circuit 52, similar to the integrated circuit 48 used in oscillator 24. A resistance and a capacitance is also used in the pulse generator 28, as in the oscillator 24, to determine the operating frequency of the pulse generator."
The IC isn't identified, but it is drawn with 7 pins, so it looks as if a 555 timer could fit the bill.
Is it possible that the Dukane ULB is using a circuit as basic and crude as the one in the 1976 patent?
native pepper said
06:31 PM Apr 14, 2014
KFT wrote:
NP if I remember correctly submarines used to use those thermal layers to hide from sonar so a black box should have no problem.
maybe they should be using sub hunters to look for what is left of the aircraft.
frank
G'day Frank, you're right, they also used them as acoustic highways and listening stations, as well as for moving quicker. Things have really changed since I was in the RAN and trained as a sonar operator. Only did a bit of it though, ended up as a quartermaster and part of ships dive teams.
Sadly to the best of my knowledge, there are no manned submersible capable of reaching that depth and functioning in a satisfactory manner. The pressure at those depths only allows for long term searching in unmanned submersibles and 4500m seems to be the limit at the moment.
-- Edited by native pepper on Monday 14th of April 2014 06:49:56 PM
Operating Frequency ... 37.5 kHz ± 1 kHz Operating Depth ... Surface to 20,000 feet (6096 meters) Pulse Length ... 10 milliseconds + 10% Pulse Repetition Rate ... Not less than 0.9 Pulse/Sec Operating Life ... 30 days (minimum) Battery Life In Beacon ... 6 Years Acoustic Output, Initial ... 1060 dynes/cm2 rms pressure at 1 meter (160.5dB) Acoustic Output After 30 Days ... 700 dynes/cm2 rms pressure at 1 meter (157.0dB) Operating Temperature Range ... +28°F (-2.2°C) to +100°F (+37.8°C) Actuation ... Fresh or salt water Radiation Pattern ... Rated output over 80 percent of sphere Size ... 1.30 inches (3.30 cm) diameter x 3.92 inches (9.95 cm) long (less mount) Weight, Beacon ... 6.7 ounces (190 grams) Weight, N30A26B Mount ... 6 ounces (170 grams) Weight, N30A21A Mount ... 3 ounces (85 grams) Storage Temperature Range ... -65°F (-54°C) to 160°F (71°C) - without battery
1.2.4. ENVIRONMENTAL TEST. The beacon complies with the preceding operational performance standards after being subjected to environmental tests specified in FAA TSO-C121.
"The printed circuit board assembly generates all the necessary logic functions to produce a pulse with the desired characteristics. The pulse is then transformed from a CMOS level square wave to a much larger 37.5 kHz sinusoidal pulse by a transformer. The output of the transformer drives the urethane-encapsulated transducer, which propagates through the housing in the form of a tuned 37.5 kHz acoustic signal."
"The device also provides stable frequency operation without a crystal-controlled oscillator over a wide range of source voltages."
It appears that this design uses two separate clocks, one for the beacon frequency, and the other for the pulse rate and duration. The clocks are derived by selecting appropriate resistor and capacitor combinations.
"Oscillator 24 [for the beacon frequency] consists of a monolithic, linear, dual-in-line integrated circuit 48, tuning resistors 44 and 46, and tuning capacitor 50. Resistors 44 and 46 and capacitor 50 determine the oscillator frequency.
Pulse generator 28 [for pulse rate and duration] additionally uses a monolithic, linear, dual-in-line package integrated circuit 52, similar to the integrated circuit 48 used in oscillator 24. A resistance and a capacitance is also used in the pulse generator 28, as in the oscillator 24, to determine the operating frequency of the pulse generator."
The IC isn't identified, but it is drawn with 7 pins, so it looks as if a 555 timer could fit the bill.
Is it possible that the Dukane ULB is using a circuit as basic and crude as the one in the 1976 patent?
Excellent information and summarisation. From what I've read, they do use a 555 and black box technology is still based on the 1976 pattern using tape, with little changes. They probably still use lead acid batteries, hence the very limited life and recording ability they have. Things may change after this, but wouldn't hold my breath waiting. If they used lifepo4, they would have signal for many months and close to a year.
-- Edited by native pepper on Monday 14th of April 2014 06:48:09 PM
dorian said
07:45 PM Apr 14, 2014
The Dukane service manual states that the battery is a lithium type with a minimum acceptable voltage of 2.97V.
Dukane's brochure states that the power source is a "Non-Haz Lithium Battery".
Current blackbox recorders use solid state memory (Crash-Survivable Memory Unit (CSMU)), not magnetic tape.
Amazing reading, interestingly the ****pit recorder only records the last couple of hours and the box has such a short recovery signal life time. Thanks
03_troopy said
07:58 PM Apr 17, 2014
This is a pic of a battery I removed from a ULB, so they definitely use Lithium batteries.
The battery chemistry is lithium-thionyl chloride (Li-SOCl2).
The discharge profile is ruler-flat with a sharp cutoff. Dukane's service manual states that a cell voltage of 2.97V is acceptable, yet the datasheet seems to be suggesting that the battery is almost completely discharged at this voltage.
dorian said
09:21 AM Sep 24, 2014
It appears that the Australian Navy spent several weeks and a gazillion dollars sailing around in circles listening to their own electronics.
The US Navy's deputy director of ocean engineering Michael Dean told CNN there was now broad agreement the signals came from some other man-made source unrelated to the jet that disappeared on March 8 carrying 239 people, six of them Australians.
"Our best theory at this point is that [the pings were] likely some sound produced by the ship... or within the electronics of the towed pinger locator," Mr Dean said.
Big Gorilla said
11:27 AM Sep 24, 2014
I can't help you with the technical side of the "Black Boxes" as we were never given the details. The Company's Operations Manual stipulated that these recorders were never to be disabled. Rather than explain myself, the operation of these recorders, I found the following information on the Internet that will give more detail.
Black box flight recorders
An aircrafts flight recorders are an invaluable tool for investigators in identifying the factors behind an accident. Recorders usually comprise two individual boxes: the ****pit Voice Recorder (CVR) and the Flight D
The Flight Data Recorder (FDR)
The FDR records flight parameters. The data recorded varies widely, depending upon the age and size of the aircraft. The minimum requirement, however, is to record a basic group of five parameters:
pressure altitude
indicated airspeed
magnetic heading
normal acceleration
microphone keying.
Microphone keying (the time radio transmissions were made by the crew) is recorded to correlate FDR data with CVR information.
This basic requirement has existed since the 1960s. Today, modern jet aircraft far exceed this, and are fitted with FDRs that can record thousands of parameters covering all aspects of the aircraft operation.
The FDR retains the last 25 hours of aircraft operation and, like the CVR, operates on the endless-loop principle. As FDRs have a longer recording duration than CVRs, they are very useful for investigating incidents and accidents.
A typical FDR is 16 cm (6.3 in) in height, 12.7 cm (5.0 in) in width and 50 cm (19.6 in) in depth. It weighs 4.8 kg (10.6 lbs).
The FDR often tells accident investigators what happened during an accident sequence and the events leading up to it.
Flight Data Recorder (FDR). Popularly known as black boxes, these flight recorders are in fact painted orange to help in their recovery following an accident.
Data storage
Older CVRs were analogue recorders which used magnetic tape as the recording medium. Modern solid-state CVRs, however, store the digitized audio information in memory chips.
Older FDRs were mostly digital recorders using magnetic tape as the recording medium. As with CVRs, modern solid-state FDRs store the digitized data in memory chips.
The ****pit Voice Recorder (CVR)
The CVR would be better named the ****pit audio recorder as it provides far more than just the voices of the pilots. In fact, it creates a record of the total audio environment in the ****pit area. This includes crew conversation, radio transmissions, aural alarms, control movements, switch activations, engine noise and airflow noise.
Older CVRs retain the last 30 minutes of an aircrafts flight. A modern CVR retains the last 2 hours of information. The newest data records over the oldest data (endless-loop principle).
A typical traditional CVR is 16 cm (6.3 in) in height, 12.7 cm (5.0 in) in width and 32 cm (12.6 in) in depth. It weighs 4.5 kg (10 lbs).
Around 80 per cent of aircraft accidents involve human factors, which means that crew performance may have contributed to the events. As a result, the CVR often provides accident investigators with invaluable insights into why an accident occurred.
The Underwater Location Beacon
Each recorder is fitted with battery-powered Underwater Location Beacon (ULB) to aid underwater recovery.
When the ULB is immersed in water, it will begin to radiate an acoustic signal which can be received and transformed into an audible signal by a receiver. The ULB is sometimes called a 'pinger' due to the audible signal created by the receiver.
The ULB must meet the following requirements:
nominal operating frequency: 37.5 kHz
size (typical): 9.95 cm long by 3.30 cm diameter
operating depth: 0 to 6,096 metres (20,000 feet)
automatic activation by both fresh and salt water
minimum operating life of 30 days. The acoustic output will decrease as the battery voltage decreases. It may be possible to still detect the ULB after 60 or more days but the detection range will be decreased.
The ULB can only be dedected by a receiver under the surface of the water. The maxium detection range of a ULB is typically up to 2 to 3 kilometres but is dependent on:
ULB acoustic output level
receiver sensitivity
whether the ULB is buried by debris (e.g. aircraft structure and mud)
the ambient noise level (e.g. sea state, nearby boats, marine animals, gas and oil lines)
water temperature gradients
depth difference between the ULB and the receiver.
Delta18 said
10:30 AM Sep 26, 2014
native pepper wrote:
The southern oscillation index of the souther ocean and its interaction with the Indian ocean.
I'm going to see if I can get that into a conversation at our regular weekly Friday night bbq!
Big Gorilla said
10:33 AM Sep 26, 2014
Delta18 wrote:
native pepper wrote:
The southern oscillation index of the souther ocean and its interaction with the Indian ocean.
I'm going to see if I can get that into a conversation at our regular weekly Friday night bbq!
I have been thinking about the MH370 incident and trying to make sense of the press releases and press conferences. Unfortunately the search coordinator and spokesperson (Angus Houston) appears to be essentially ignorant of the technology involved. His explanations are just technobabble.
For example ...
http://qanda.newscontent.cctv.com/news.jsp?fileId=236215 (April 8, 2014)
"The advice from the manufacturer is that 33 kHz is, or 33.2 kHz, is quite credible. The Air France locator battery from five years ago was 34 kHz. So, what happens is, there is a change with the pressure on the ocean floor and the age of the particular batteries, the capacitance can change and you get changes in the transmission level."
"The Air France locator battery from five years ago was 34 kHz."
No Angus, a battery doesn't produce a frequency, it produces voltage and current. In any case, the blackboxes were not found until two years after the crash, and the frequency was only determined after reanalysing the sonar records of a French submarine long after the event.
http://en.wikipedia.org/wiki/Air_France_Flight_447
"While the Brazilian Navy removed the first major wreckage and two bodies from the sea within five days of the accident, the BEA's (Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile) initial investigation was hampered because the aircraft's black boxes were not recovered from the ocean floor until May 2011, nearly two years later."
"The advice from the manufacturer is that 33 kHz is, or 33.2 kHz, is quite credible."
I wonder if the AF447 investigators actually tested the Underwater Locator Beacon (ULB) after it was retrieved (after replacing its battery, of course). In fact, I would suggest that the MH370 investigators obtain other ULBs from Malaysia Airlines, preferably from the same batch, or at least the same model and vintage, and then subject them to some simple tests of their own, without relying on the information from the manufacturer (Dukane Seacom). Specifically, I would remove the existing battery (3V lithium) and replace it with a variable DC power source, say 0V - 3.6V. Then record the emitted frequencies and sound pressure levels. That should tell us whether 33.2kHz is "credible".
Another idea would be to use Bluefin (Autonomous Underwater Vehicle) to take a few of these ULBs to the bottom of the ocean and perform some simple tests.
"there is a change with the pressure on the ocean floor".
The manufacturer specifies that its ULB is certified for correct operation at a depth of 20,000 feet (approximately 6000 metres). Apparently this is a requirement of the relevant standard (TSO-C121). Therefore, it makes no sense to say that a depth of 4500m is responsible for the reported frequency deviation.
"you get changes in the transmission level"
"Transmission level" and "frequency" are not the same thing. The first relates to the amplitude, ie strength, of the signal, not its frequency. A weak battery will undoubtedly result in a reduced transmission level, but I find it difficult to understand how it would affect the frequency.
"the capacitance can change"
I would have thought that a ULB that sells for upwards of $1500 would have high quality components with negligible drift. In applications where temperature and frequency stability are paramount, a designer would specify a capacitor with a zero temperature coefficient and negligible leakage. For example, an NPO ceramic capacitor would have such characteristics. A frequency of 33.2kHz represents an 11.5% deviation from the specification. A $5 wrist watch (with a 32.768 kHz tuning fork crystal) can keep time with an accuracy of 10 parts per million, so why can't a $2K piece of avionics do as well as that?
Why does the 37.5kHz beacon have a tolerance of +/- 1kHz? That's about +/- 3%. What are they using for a clock source? I doubt that they would be using a quartz crystal, as these will shatter when subjected to relatively minor impacts. Could they be using a ceramic resonator, or are these also prone to shattering? Are they using a simple RC arrangement, and is this why the tolerance is so wide?
If the frequency of the beacon has in fact been reduced to 33.2kHz, then how has this affected the pulse width (10ms) and separation between pulses (1.1 second)? If the circuit is timed from a single clock source, then one would expect that the other two parameters would have drifted from the spec in exactly the same proportion. Is the separation between pulses now 1.25 sec, or has it remained at 1.1 sec? Is the pulse width now 11.5 msec? ISTR that Angus Houston mentioned 1.1 second as the pulse separation, so what is happening here? Is the ULB just some cheap RadioShack kit stuffed inside an expensive pressure vessel?
Gday...
Thanks Dorian
Ya know, I actually read ALL that. Unfortunately, I still don't know anything more about a "black box/beacon/thingy" or anything that you were talking about.
But at least you attempted to illuminate the rest of us. Perhaps you should send this in an email to Angus.
Cheers - John
Between the surface and 4500m to the bottom, there are many thermal, tide, current layers and columns of water with varying temperatures, salinity, density and atmospherics pressures. These have a big bearing on signal strength and frequency, plus signal can be diverted by these phenomena. When you consider where this is all taking place and look at the dynamics of the southern oscillation index of the souther ocean and its interaction with the Indian ocean. it's easy to see why they are having such trouble with firmly locating exactly where the signals are coming from at such great depth and pressure.
maybe they should be using sub hunters to look for what is left of the aircraft.
frank
Technical Manual, Dukane Underwater Acoustic Beacon, Models DK100/DK120/DK130/DK140:
www.rjeint.com/pdf/DK100Series_16.pdf
Operating Frequency ... 37.5 kHz ± 1 kHz
Operating Depth ... Surface to 20,000 feet (6096 meters)
Pulse Length ... 10 milliseconds + 10%
Pulse Repetition Rate ... Not less than 0.9 Pulse/Sec
Operating Life ... 30 days (minimum)
Battery Life In Beacon ... 6 Years
Acoustic Output, Initial ... 1060 dynes/cm2 rms pressure at 1 meter (160.5dB)
Acoustic Output After 30 Days ... 700 dynes/cm2 rms pressure at 1 meter (157.0dB)
Operating Temperature Range ... +28°F (-2.2°C) to +100°F (+37.8°C)
Actuation ... Fresh or salt water
Radiation Pattern ... Rated output over 80 percent of sphere
Size ... 1.30 inches (3.30 cm) diameter x 3.92 inches (9.95 cm) long (less mount)
Weight, Beacon ... 6.7 ounces (190 grams)
Weight, N30A26B Mount ... 6 ounces (170 grams)
Weight, N30A21A Mount ... 3 ounces (85 grams)
Storage Temperature Range ... -65°F (-54°C) to 160°F (71°C) - without battery
1.2.4. ENVIRONMENTAL TEST. The beacon complies with the preceding operational performance standards after being subjected to environmental tests specified in FAA TSO-C121.
Dukane DK120 Brochure:
rjeint.com/pdf/DK120.PDF
"The DK120 is equivalent to Benthos (Datasonics) ELP-362D Emergency Locator Beacon ..."
Teledyne Benthos ELP-362D Emergency Locator Beacon User’s Manual:
www.benthos.com/_doc/main/Brochures_Datasheets/elp362D__001815__rev_L.pdf
"The printed circuit board assembly generates all the necessary logic functions to produce a pulse with the desired characteristics. The pulse is then transformed from a CMOS level square wave to a much larger 37.5 kHz sinusoidal pulse by a transformer. The output of the transformer drives the urethane-encapsulated transducer, which propagates through the housing in the form of a tuned 37.5 kHz acoustic signal."
Here is a 1976 US patent for a Programmable Underwater Acoustic Beacon:
patentimages.storage.googleapis.com/pdfs/US3992692.pdf
"The device also provides stable frequency operation without a crystal-controlled oscillator over a wide range of source voltages."
It appears that this design uses two separate clocks, one for the beacon frequency, and the other for the pulse rate and duration. The clocks are derived by selecting appropriate resistor and capacitor combinations.
"Oscillator 24 [for the beacon frequency] consists of a monolithic, linear, dual-in-line integrated circuit 48, tuning resistors 44 and 46, and tuning capacitor 50. Resistors 44 and 46 and capacitor 50 determine the oscillator frequency.
Pulse generator 28 [for pulse rate and duration] additionally uses a monolithic, linear, dual-in-line package integrated circuit 52, similar to the integrated circuit 48 used in oscillator 24. A resistance and a capacitance is also used in the pulse generator 28, as in the oscillator 24, to determine the operating frequency of the pulse generator."
The IC isn't identified, but it is drawn with 7 pins, so it looks as if a 555 timer could fit the bill.
Is it possible that the Dukane ULB is using a circuit as basic and crude as the one in the 1976 patent?
G'day Frank, you're right, they also used them as acoustic highways and listening stations, as well as for moving quicker. Things have really changed since I was in the RAN and trained as a sonar operator. Only did a bit of it though, ended up as a quartermaster and part of ships dive teams.
Sadly to the best of my knowledge, there are no manned submersible capable of reaching that depth and functioning in a satisfactory manner. The pressure at those depths only allows for long term searching in unmanned submersibles and 4500m seems to be the limit at the moment.
-- Edited by native pepper on Monday 14th of April 2014 06:49:56 PM
Excellent information and summarisation. From what I've read, they do use a 555 and black box technology is still based on the 1976 pattern using tape, with little changes. They probably still use lead acid batteries, hence the very limited life and recording ability they have. Things may change after this, but wouldn't hold my breath waiting. If they used lifepo4, they would have signal for many months and close to a year.
-- Edited by native pepper on Monday 14th of April 2014 06:48:09 PM
Dukane's brochure states that the power source is a "Non-Haz Lithium Battery".
Current blackbox recorders use solid state memory (Crash-Survivable Memory Unit (CSMU)), not magnetic tape.
www.funzug.com/index.php/technology/what-are-airline-black-boxes.html
Amazing reading, interestingly the ****pit recorder only records the last couple of hours and the box has such a short recovery signal life time. Thanks
This is a pic of a battery I removed from a ULB, so they definitely use Lithium batteries.
Here is a datasheet:
http://www.saftbatteries.com/system/files_force/LS26500.pdf?download=1
The battery chemistry is lithium-thionyl chloride (Li-SOCl2).
The discharge profile is ruler-flat with a sharp cutoff. Dukane's service manual states that a cell voltage of 2.97V is acceptable, yet the datasheet seems to be suggesting that the battery is almost completely discharged at this voltage.
www.abc.net.au/news/2014-05-29/mh370-us-navy-dismisses-experts-comments-on-search-pings/5485970
The US Navy's deputy director of ocean engineering Michael Dean told CNN there was now broad agreement the signals came from some other man-made source unrelated to the jet that disappeared on March 8 carrying 239 people, six of them Australians.
"Our best theory at this point is that [the pings were] likely some sound produced by the ship... or within the electronics of the towed pinger locator," Mr Dean said.
I can't help you with the technical side of the "Black Boxes" as we were never given the details. The Company's Operations Manual stipulated that these recorders were never to be disabled. Rather than explain myself, the operation of these recorders, I found the following information on the Internet that will give more detail.
Black box flight recorders
An aircrafts flight recorders are an invaluable tool for investigators in identifying the factors behind an accident. Recorders usually comprise two individual boxes: the ****pit Voice Recorder (CVR) and the Flight D
The Flight Data Recorder (FDR)
The FDR records flight parameters. The data recorded varies widely, depending upon the age and size of the aircraft. The minimum requirement, however, is to record a basic group of five parameters:
Microphone keying (the time radio transmissions were made by the crew) is recorded to correlate FDR data with CVR information.
This basic requirement has existed since the 1960s. Today, modern jet aircraft far exceed this, and are fitted with FDRs that can record thousands of parameters covering all aspects of the aircraft operation.
The FDR retains the last 25 hours of aircraft operation and, like the CVR, operates on the endless-loop principle. As FDRs have a longer recording duration than CVRs, they are very useful for investigating incidents and accidents.
A typical FDR is 16 cm (6.3 in) in height, 12.7 cm (5.0 in) in width and 50 cm (19.6 in) in depth. It weighs 4.8 kg (10.6 lbs).
The FDR often tells accident investigators what happened during an accident sequence and the events leading up to it.
Flight Data Recorder (FDR). Popularly known as black boxes, these flight recorders are in fact painted orange to help in their recovery following an accident.
Data storage
Older CVRs were analogue recorders which used magnetic tape as the recording medium. Modern solid-state CVRs, however, store the digitized audio information in memory chips.
Older FDRs were mostly digital recorders using magnetic tape as the recording medium. As with CVRs, modern solid-state FDRs store the digitized data in memory chips.
The ****pit Voice Recorder (CVR)
The CVR would be better named the ****pit audio recorder as it provides far more than just the voices of the pilots. In fact, it creates a record of the total audio environment in the ****pit area. This includes crew conversation, radio transmissions, aural alarms, control movements, switch activations, engine noise and airflow noise.
Older CVRs retain the last 30 minutes of an aircrafts flight. A modern CVR retains the last 2 hours of information. The newest data records over the oldest data (endless-loop principle).
A typical traditional CVR is 16 cm (6.3 in) in height, 12.7 cm (5.0 in) in width and 32 cm (12.6 in) in depth. It weighs 4.5 kg (10 lbs).
Around 80 per cent of aircraft accidents involve human factors, which means that crew performance may have contributed to the events. As a result, the CVR often provides accident investigators with invaluable insights into why an accident occurred.
The Underwater Location Beacon
Each recorder is fitted with battery-powered Underwater Location Beacon (ULB) to aid underwater recovery.
When the ULB is immersed in water, it will begin to radiate an acoustic signal which can be received and transformed into an audible signal by a receiver. The ULB is sometimes called a 'pinger' due to the audible signal created by the receiver.
The ULB must meet the following requirements:
The ULB can only be dedected by a receiver under the surface of the water. The maxium detection range of a ULB is typically up to 2 to 3 kilometres but is dependent on:
I'm going to see if I can get that into a conversation at our regular weekly Friday night bbq!
Far too testicle for me !!
A bit on the seabed they are scanning, see;
http://www.abc.net.au/news/2014-09-27/deep-sea-volcanoes-discovered-in-search-for-mh370/5774122