Not a continuous tone
 

No, it's not a continuous tone. My only question is whether it has modulation. I have not read about that, so my bet is that it is not modulated.

You may be thinking of 121.5/243 MHz RF ELT's - a very different beast. They emit a continuous RF signal with frequency swept AM modulation that sounds like an alert siren. Newer ones emit less power than in the past, because the primary beacon is now a periodic digital burst on about 406 MHz, and the VHF signal is intended only for localization as opposed to primary detection.

Burst signals give better battery life. You get better detection with short loud (higher power) bursts than long quieter ones. However, more modern equipment, in theory, can do about the same with either one (by integrating the long quieter signal over time achieving the same SNR as the short louder one).

pingers and news events
 

Back again after reading lots of threads on here re why where who it was and about how this person/nation is screwed up and how the Americans/Brits/ Oz ect ect can handle it better.

Come on guys get real. there are 239 lost souls on that aircraft as well as the fact that there are other 777 aircraft or aircraft of the same build standard out there flying about.

If some one finds a ping or signal that may or may not lead to finding this hull or what ever is left of it then thats good for the investigation good for the industry and not to mention some closure for the relatives. I dont care who finds what so long as some one does and if as I hope it turns out that it is in fact credible and the hull is located then the real investigation can start to swing into action and we can all get the answers that we need to know.

In answer to some threads on here about the Malays holding back info. Yes they have a right to with hold what ever they feel should not be released at that present time. The police when they investigate crimes do not allways release all the information on the incident under investigaion and should not be expected to lest they give away vital clues they dont really want others to know that they know. So to all those who are hammering the Malays and the others involved in this regarding release of information to just back off and let them get on with it. Let them concentrate on the task of finding the hull and not have to ansewer so many stupid questions and defending the line they are taking.
The time to hang and go after them if there is a need will be at the end when its all settled and the wash up takes place. Wait for the final report on this to be published and then and only then if there is a need to comment that will be the time to do so..

Oh CNN, I have stopped watching your coverage, what a load of cobblers some of your specialists spout and no doubt enflame the situation with the relatives. I cant watch and listen any more. Chanel news asia is a bit better:ugh:

Slang for an RIB.

Not a continuous tone - Agree
 

http://rjeint.com/pdf/DK120.PDF
and the 8.5 Khz
http://www.radiantpowercorp.com/file...2501338125.pdf

Various reports have the acoustic signals heard by the Chinese ship at 25°S 101°E. That's basically right on top of the 0:11 UTC 40° satellite ping arc calculated by Inmarsat, is it not?

In the PC, A. Houston did his utmost to "smooth the waters" of the Chinese adherence to the overall plan, and give them much credit, but it does seem from awkward answers at times that there may have been some worrisome issues heretofore. His 2 hour meeting with the ambassador last night as well as his "realistic acceptance" that on-site press might sometimes jump the gun, all seem designed to improve the situation going forward.

Yes, the Chinese were "roughly in the general search area", in fact closer to the "just refined satellite re-look" that gives "more probability" to the southern boundary of the search area. Perhaps the Chinese experts independently tinkered with the satellite data that suggests this; or maybe their satellite or aircraft sightings were part of the equation for their focus.

It seems the Chinese ship, the HMS Echo, and the Ocean Shield all have different capabilities to verify and otherwise decipher acoustic events, with (per A. Houston and the Commodore) the Ocean Shield being the ablest. It is a shame therefore that it may be delayed 2 days before getting to the Chinese incident area, to do it's own separate acoustic verification, as battery life dwindles. I would think another "equally able" ship (USA or otherwise) would be an invaluable asset just about now!

Not just semantics
 

This isn't just semantics.

When talking about signals, "continuous" has a specific meaning.

This signal is off over 99% of the time. That means the battery can last almost 100 times as long, or it can use over 100 times (20dB) the signal power than a continuous signal. It also means that, if it is heard regularly for short bursts, the probability that it's a ULB rather than an artifact is much higher than the detection of a continuous signal - because this gives a signature unlikely to be found in nature or from unrelated technology.

In signal processing - i.e. what you need to do detection - all of this is very important.

In terms of search strategy, I suppose it could be thought of as "frequent" in the sense that you are likely to hear the signal more than once during a detection.

CNN is reporting...
 

"A British Royal Navy vessel is on its way to an area where a Chinese ship reported picking up electronic signals twice, once on Friday and again on Saturday, said Angus Houston, the head of the Australian agency coordinating search operations.

And the Australian naval ship Ocean Shield, which has highly sophisticated equipment, is pursuing "an acoustic noise" that it detected in a different area, Houston said at a news conference.

He said the detections were "an important and encouraging lead," but he cautioned that they be treated "carefully" as they haven't been verified as being related to Flight 370".

Underwater Locator Beacon & Towed Pinger Locator
 

All the acoustic pings are 10 milli Sec long. At a once per second repetition rate. In good conditions the 190 gram! Dukane ULB can be detected by the Phoenix Model 25 Towed Pinger Locator within 12,000 Ft.

abc is reporting...
 

"....Angus Houston said the British navy's HMS Echo, which is fitted with sophisticated sound locating equipment, is moving immediately to the area where the Haixun 01 detected the signals. The Australian navy's Ocean Shield, which is carrying high-tech sound detectors from the U.S. Navy, will also travel to the area".

With respect to receiving the underwater pings.

If the pings are regular and for 10 ms every 1 second. Would it not be possible to take the received signal over that period and then sum/pile each 1 second of reception on top of each other 1 second of reception at that frequency in order to improve the signal to noise ratio?

I have done similar things in both amateur radio and also in astrophotography where you sum the received light from night photos to get a better pictures of faint objects. Essentially you improve the signal to noise ratio by doing so.

I hope that the aircraft and ships are recording their reception of the 37.5 khz frequency and time stamping it because later computer analysis using methods such as outlined above could pull out signals that are not audible to the human ear. The news that the Chinese were not recording what they were hearing doesn't sound good however. I hope teh othernatiosn searching are recording all their received static.

The No 1 guy who should be consulted re picking out weak signals like this is Professor Joe Taylor K1JT who is a noble laureate in physics. he has designed software that enables a weak signal of less than a watt to be heard and identified/decoded on the other side of the world.

Its called intergrating, and doing it in a cyclic fashion on a known period is called folding your data in pulsar speak. Its all fairly basic signal analysis that the people doing the searching will know about.

The guys/gals out there are generally profesionals and will know most techniques and when to apply them. Yes occasionally there are Darwin moments, but not usually.

The Chinese are playing to "two masters" and the Chinese news agency seems to like to "be first".

If they find it, does it really matter ?

And as long as JACC/AMSA get the info as well, I doubt anyone really cares.

PJm

Agree but given the size of a search area it is unlikely to have been covered, particularly by towed array which also leads into my other query “Why was the ship outside the search area and if it was transiting would it not be quicker to do so without a towed array or can it detect without a towed array.”

The problem with the suggestion of a criminal act by the captain motivated by political considerations is it just doesn't make sense.

What could anyone hope to achieve by making a jet disappear without trace? It might hurt Malaysian Airlines a little but it is not like any blame can be shot back to the Malaysian Government. If anything the Captain's associations with the opposition seem to work in the Government's favour.

Deliberate Stealth Route
 

"Malaysia Airlines Flight 370 flew north of Indonesia and around Indonesian airspace in its journey to the southern Indian Ocean, a senior Malaysian government source told CNN.
The conclusion was reached by investigators after reviewing radar track data from neighboring countries.
The plane did not fly over Indonesia or its airspace after making a westward turn in the South China Sea and flying across the Malaysian Peninsula, the source said."

I had opined several hundred pages ago that there was no way the aircraft flew over Sumatera without being detected and challenged, especially in view of the sensitivity of Aceh Province to Indonesia.


Whilst I understand that neither source is entirely credible, this is the first report that, indeed, the aircraft deliberately avoided radar tracking by both Thailand AND Indonesia.


So the aircraft turned West, then North, Then West again, and finally South/South West towards the South IO. This would appear to eliminate ALL possibility that the aircraft was flying out of control as a result of a technical problem, after the ACARS and SSB had been "Lost".


The Black boxes, if ever found, might not really help explain. The CVR is only good for 2 hours and whilst the DVDR might eliminate technical difficulties, can it really show what actually happened? It seems clearer by the day that SOMEONE didn't want the aircraft's flight path to be recorded or any "Evidence" found afterwards and deliberately chose the South IO to "Loose" all trace?


The question as to who is that SOMEONE or SOMEONES may never be answered?

I'm not really sure that this is new news. Most of the possible flight paths I've seen have had MH370 jogging to the North for some weeks now. Maybe what they are intending to point out is that they now believe it to be a deliberate act?

there were so many false rumours on the flight track and so many speculative theories what happened that such news do not have much weight now. let them find the wreckage and we will see someday what and why happened - today no person in the world can say .

Media Hype
 

"I'm not really sure that this is new news. Most of the possible flight paths I've seen have had MH370 jogging to the North for some weeks now. Maybe what they are intending to point out is that they now believe it to be a deliberate act?"

Actually it IS to the extent that ALL the MSM have been showing a flight path right over Sumatera after turning West.


Incidentally, the other "Loose end" is that, to the best of my knowledge, MH have STILL not released the Cargo Manifest, despite having promised to do so on many occasions. Why is that??

"Why is the Captain theory so insisted on by many here ? Are the crew the only ones who could fly the aircraft ? Not so in 9/11.
But. This is not organised Hijack so if a Hijack at all some. Lone wolf passenger with some knowledge of aviation!
But there is no purpose to a HiJack! No destination ( a crew would not run out of fuel trying to reach somewhere which they had no chance of reaching!
A part knowledge passenger maybe !"

Agreed. All we know is that the Captain was a passionate and dedicated Airman. There is NO evidence from Malaysian authorities OR from the CIA/FBI/NSA that I am aware of, to the contrary. And the First Officer was the Son of a Senior Malaysian Government Official.


Of course, at this stage, nothing is impossible but I do think we should continue to respect the Flight crew until proven otherwise.