Datayq1

We assume that JACC is listening to experts, but apparently none of them are within Dr Gallo's sphere of underwater acoustics "people".

Mesoman

If the article is correct, this would be a bombshell.

But... I'd like to see someone else, or Woods Hole itself, corroborate this. After all, the pings were picked up by the experts using the TPL, and their whole job is finding these pingers. Aussie acoustic experts reportedly (per Angus Houston) verified them.

Thus I find it unlikely (but not impossible) that the searchers are on the wrong track in this regard. More likely is that the article is wrong and the authorities are misquoted. I suspect we'll know one way or the other in a day or two.

Currently, the Woods Hole site, which has a FAQ on this search, doesn't mention ULB's at all.

Pontius Navigator

And these tags are mobile. If the carrier of the tag was responsible for each located ping being in a different area then it is probable that at least two pings would have been on different, Doppler-shifted, frequencies to account for the variation in locations.

Had there been such a tag set to operate at that frequency I would have expected to someone to come up and say, 'Hey guys, you are tracking my great white . . . '

James7

MH370 families urge govts to release raw satellite data - The Rakyat Post - The Rakyat Post

Reacting to the tripartite meeting, Voice370 said given the lack of tangible evidence of what happened to MH370, Putrajaya should “share and release the raw Inmarsat satellite engine ping data for 9MMRO (every ping from Friday, March 7 midnight until the final signal), “so that it can be subject to broader analysis by relevant experts”.
Voice370 said Inmarsat’s data only indicated a probable southern flight path but that it was not a definitive conclusion.
“The Inmarsat satellite data is the only lead we have and is key to identifying MH370’s flight path,” it said.
“In view of the lack of emergency locator transmitter (ELT) activation, zero detected debris, and the lack of convincing pings, we feel that it is necessary that the data be subjected to independent third party review,” the group said.

henra

In order to emulate exactly the Doppler effects and Signal strength of the SAT Connection.
Winds/conditions are irrelevant for that. It would be important to get the timing right relative to the Satellite position and movement.
When replicating 1:1 it should become possible to identify deviations from the calculated/assumed course/speed combination, thereby validating the current search area.
Amplitudes and steepness of Doppler shift change should be identical.
If this cannot be replicated exactly 1:1 it may be time for a re-think.
Plus the steepness of the change of Doppler shift tells you something about the effective Speed vector of the aircraft relative to the satellite.
Steeper drop in Doppler means faster airspeed or more orthogonal course relative to the arc.
Since there is a mutual dependency of Speed, angles relative towards the arcs and timing of crossing of the different arcs, you could draw conclusions regarding where exactly to search from deviations or match of the values seen with MH370.
Edit: The more orthogonal the course relative to the arcs, the more even spaced will the Timings be between crossing the different arcs (if we assume a constant airspeed in the last stage of the flight). Thus there will be a more or less unique pattern for each combination of Speed and course, only limited by the accuracy of the data.

aerobat77

i somehow fail to understand all this ...


we remember the reports where the search teams received pings which


a) were on the final arc of handshakes
b) were recorded, anylysed and verified to be from an ULB.
c) started to fade out at the 30 day battery limit.


knowing the very limited range of the ULB pinger and using common sense to realise its to much concidence that a b and c together can be anything else than really mh 370 could lead to say " deepest respect you aussies - you really found the wreckage" ,just send the auv to confirm.


they did and... nothing ...


so in this mystery i see only two explanations


a) all the rumours are false, the pings were never from a blackbox ULB and they search in a more or less complete wrong position
b) the pings were from a blackbox ULB - and since no other aircraft crashed there last time for sure it can only be mh370 - but the bluefin is much more limited than released to media and simply failed to scan the wreckage even when it was in the right spot.


i do not see other explanations - normally when you hear the ULB you have found the aircraft.

overthewing

A site about acoustic tags on marine animals says:

Ocean Tracks | Acoustic Tags

I presume that the SAR investigators were able to rule out the possibility of coded tags, for lack of that unique identifying number? (And why doesn't an aviation ULB broadcast the same unique information?)

That leaves continuous pingers as a possibility. Presumably, marine researchers have records of what they've tagged and where those tags were last 'heard'? And presumably the MH370 investigators will have co-ordinated with those science agencies?

There has to be a reason for the Australian's certainty about the source of the pings. Doesn't there?

HeavyMetallist

If the audio was modulated with a code then that would have been very obvious when they analysed the signals.

As for uniquely coding aviation ULBs - there's not a lot of point since, unlike with tagged animals, in any given ocean in any given 30-day period it's hardly likely that there will be more than one pair of ULBs down there!

overthewing

But if an aviation ULB can't be distinguished from a similar device attached to an animal, you're depending on the aircraft crashing in an area where there aren't likely to be any tagged animals?

HeavyMetallist

But they can be distinguished - aviation ULBs aren't coded, and transmit in bursts at 1 second intervals, not continuously. They also transmit around one frequency and will only have a doppler shift related to the velocity of the locator. If you've detected the signal over any substantial period of time I don't think it's going to be at all difficult to tell it apart from a marine animal tag.

catch21

Experts disagreeing with each other is nothing new, it's happening in court rooms around the world all day long.

What makes this extraordinary is that there are now two sets of experts disagreeing with each other, both over different sorts of pings, ULB pings and Satellite Pings.

Judging by the Atlantic article, it doesn't seem to me that the experts disagreeing (with the search authorities collective) on the issues of the satellite pings are Terry-Halfwit-with-a-calculator types. They would seem to have credibility, and I would hope they're now being listened to.

From the Malaysian Insider article, there would appear to be reasonable doubt cast by outside experts on the authenticity of the ULB pings as well.

I certainly wouldn't question the wisdom of the search strategy so far, (I've been involved in SAR for many years and it is always obvious afterwards), but given the lack of physical evidence I don't think it is unreasonable at this point to expect a re-think and a fresh analysis of the whole incident.

overthewing

I can't find information on what 'continuous' means in terms of marine tag pinging. One site states:

www.asfb.org.au/pdf/1999/1999-01-05.pdf

That suggests to me that there's a pulsing behaviour involved? I don't know whether that means microseconds or something in the order of minutes or hours. Is it implausible that a marine tag could be set to pulse at 1 second intervals? Or is this disallowed, on account of confusion with aviation ULBs? The transmission frequency detected was consistent with what marine scientists use to track animals in deep ocean, because the lower frequency travels further.

aerobat77

"They did seem very sure that they had located a ULB though, in which case, your original point would still stand"


correct. lets forget all handshakes and inmarsat - when you receive in the middle of the indian ocean where no other aircraft crashed short range stationary pings from a device that is confirmed to be a blackbox ULB which start to fade away just 30 days after mh 370 vanished - what else can it be than a malaysian boeing 777 directly unter your feet ?


this pings either never existed or were from another source OR bluefin is not able to fully scan the bottom because otherwise MH370 must have been found .

Recc

From the paper linked in the article:

"We developed the RATS to track the model V22P acoustic transmitter [...] which is specified to transmit a 36-kHz “ping” at 165 dB once every 700–1100 ms. The pulse duration of the ping is 10 ms"

oldoberon

If I have understood the whale/shark tracking posts I have one question.

Why on earth (or this case in the sea) are they allowed to use a frequency 5khz either side of 37.5Khz - madness

Isn't there a control authority like radio frequencies.

henra

Ouch.
This sounds worryingly close.
That might be: "back to square 1" I guess.
If true this leaves one speechless.

HeavyMetallist

@Recc:
You forgot to mention that the 700-1100ms pulse interval isn't a tolerance, it's a range; the pulse interval is varied to encode the depth of the transmitter. The chance of it being precisely, and consistently, 1s is therefore remote, and readily distinguished from an aviation ULB.

Recc

True, but I wasn't meaning to suggest that it was this particular model; it was just an example of the kind of technology that was out there. The basic model (for example) comes with a factory set pulse interval and frequency (between 34 and 50kHz).

thommo101

@Rampstriker
Before people buy the hype from that article, let me remind you that these types of acoustic tracking tags are designed for SHORT TERM deployments on whales allowing for high resolution tracking with suitable distributed receivers.

For example the unit in the above paper lasted for 4 and a half hours attached to the whale.

These types of pingers are NOT deployed for long term detection.

Examples of pingers that ARE designed for long term (mentioned in @overthewing's post) are higher in frequency (62kHz), do not ping as regularly, and and rather low power (~145dB SL). These are used for shark tagging around Australia.

Now I'm not saying the signals detected by Ocean Shield are NOT from acoustic whale tags. All I am saying is it is HIGHLY IMPROBABLE that they originated from a whale tag.

RationalKeith

My understanding from credible comments in fora like this is that the combination of frequency and modulation method is different for various uses, aviation recorder beacons are unique.