'Contact lost' with Malaysia Airlines plane

Audio compression is pretty trivial and has been common place for decades, there are minimal computation requirements.

Like I said though, compression isn't even required. Voice recording in particular requires very little space.
 
Energize said:
Audio compression is pretty trivial and has been common place for decades, there are minimal computation requirements.

Like I said though, compression isn't even required. Voice recording in particular requires very little space.
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The FDR does not record audio it records data. The CVR records audio which is where I think the confusion is.
 
Energize said:
What confusion? You say the FDR can record 25 hours, so that means the CVR which we are talking about is 2 hours?
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No idea how much the CVR can record on this 777.

The FDR and CVR although housed in the same unit have their own storage for recording. The FDR as per Boeings update is approx 25 hours of data storage from the FDR. I have no idea what the CVR can record without looking into it.

I was saying the confusion that the FDR only records 2 hours might be being confused with the CVR recording time.

This pic might help..



Universal Avionics “CVFDR” includes a line of Cockpit Voice (CVR) and Flight Data (FDR) recorders available in five model options, providing a customized recording solution for your aircraft. The CVFDR offers an independent as well as a combination or “combo” cockpit voice and flight data recording capability, each with an internal Recorder Independent Power Supply (RIPS) option. Weighing less than nine pounds, the lightweight and compact CVFDR is the most advanced and convenient recorder available today.

The CVFDR provides 120 minutes of independent cockpit voice and ambient audio recording, as well as 120 minutes of data link messaging recording. It records at least twenty-five hours of flight data recording and interfaces with data downloader tools to allow quick download of data from virtually any aircraft between flights. The unit also features an Ethernet interface for on-aircraft data downloading.

Its unique internal RIPS option provides a backup power source in the event of a main power failure and allows aircraft to meet the FAA’s latest RIPS requirement without the additional size, weight and complexity of an external RIPS unit. Universal’s proprietary technology provides these capabilities without the need to maintain internal batteries.

The CVFDR was developed in compliance with the newest, most rigorous testing and crash survivability standards stipulated by the U.S. Federal Aviation Administration (FAA) and other aviation authorities around the world. Operators can now meet all published and emerging regulations for cockpit voice, digital flight data and data link recording with the convenience of a small, lightweight unit.
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MOOGLEYS said:
So do most people :) They are just a very robust external drives. There is a recording device which is now solid state and a power supply. Then bolted to the outside is the Sonar Locator Beacon.

There is lots of story's on why they are called "Black Boxes" but as boring as it is they are called it because they used to be black.
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Was there any reason why they used to be black? I would have thought that right from the start they would have been made as obvious as possible in as many ways as possible, including visually.
 
According to wiki the term 'Black Box' has nothing to do with it's physical appearance but describes it's implementation.
 
The ping location:

uqoj.jpg


It appears that a second one was heard within hours of the first. HMS Echo and Australian vessel the Ocean Shield are now heading for the area.
 
If the shades of blue accurately reflect depth it seems not to be in the deepest areas. When I read the BBC article it seemed to be saying that Ocean Shield was investigating a third acoustic signal elsewhere. Why isn't that hit getting any publicity ?
 
Cosimo said:
The ping location:

It appears that a second one was heard within hours of the first. HMS Echo and Australian vessel the Ocean Shield are now heading for the area.
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Both by chinese vessels who have the most emotional investment in finding it, both were only heard fleetingly by human ears, no recording was made, I can't help but wonder if its wishful thinking as the chances of it finding it so quick must be very low. Lets hope it doesn't distract the search from other areas.
 
Tuppy_Glossop said:
When I read the BBC article it seemed to be saying that Ocean Shield was investigating a third acoustic signal elsewhere. Why isn't that hit getting any publicity ?
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It is getting publicity. :confused:

http://www.theguardian.com/world/2014/apr/06/mh370-search-continues-after-black-box-ping-claim

The third signal was detected on Sunday morning by the Australian navy ship Ocean Shield, located around 300 nautical miles away from the Chinese ship.

Houston said he did not know at this stage whether the acoustic signal detected by Ocean Shield was 37.5kHz, the frequency emitted by a black box locator beacon, but the lead was “something that needs to be investigated”.
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also.

http://www.dailymail.co.uk/news/art...n-detected-HMS-Echo-en-route-investigate.html
 
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Blackjack Davy said:
Both by chinese vessels who have the most emotional investment in finding it, both were only heard fleetingly by human ears, no recording was made, I can't help but wonder if its wishful thinking as the chances of it finding it so quick must be very low. Lets hope it doesn't distract the search from other areas.
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When they heard it, why didn't they home in on the signal? How can they let the signal escape without moving in to confirm? Left the heating on at home or something?
 
I must say I find it highly unlikely that these 'pings' will turn out to be genuine. I wouldn't be surprised if false positives are deliberately being reported by China to keep the story in the news.
 
Hikari Kisugi said:
Eh?
They are ultrasonic frequencies, how do you hear it by human ears?
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Apparently they use a device that shifts the frequency down to the level the human ears can detect.

But the Chinese seem to be using a device that is not intended for this use and is basically a handheld divers bit of kit, whilst the properly equipped ships will be using more advanced and sensitive equipment, and will be able to record the original signals as they are when received, and then apply various filters and fine tuning to the recoding.

In effect the Chinese may be picking something up that is in a similar range, but because the equipment they are using is not designed for that use, and is quite basic the margin of error with it is very high (it sounds like it's a simple frequency shifter, probably with a fixed setting and no way to record the original signal as picked up).
Of course the Chinese could be saying it's been detected by their known surface ship, when in reality it's been picked up by a sub that they don't want the Aussies to know is in the area...
 
rubberduck said:
I must say I find it highly unlikely that these 'pings' will turn out to be genuine. I wouldn't be surprised if false positives are deliberately being reported by China to keep the story in the news.
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It might turn out to be nothing but the Australians have picked up a signal too apparently. I don't know if it is supposed to be the same one as the Chinese picked up though. Either way finding a signal gives some hope that they have found it.
 
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