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      04-02-2014, 12:15 PM   #265
Soorena
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Correct me if i'm wrong, but authorities believe that the plane crashed in ocean near Perth only if the plane's flight path was the southern arc that Inmarsat provided. How they ruled out the northern arc path?

This is the arcs i'm referring to:
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      04-02-2014, 12:21 PM   #266
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They ruled out the northern area by performing a Doppler frequency shift analysis on the signal they received. The satellite in question is stationed in a geostationary equatorial orbit but shifts slightly north and south. This relative movement results in a frequency shift depending on if the satellite was moving toward or away from the transmission source at time of transmission/receipt. They corroborated this analysis with signals received at the same time from known transmitters (other airplanes talking to this satellite). The result indicated that the signal originated from the southern direction.
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      04-02-2014, 12:42 PM   #267
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Quote:
Originally Posted by jwzimm View Post
They ruled out the northern area by performing a Doppler frequency shift analysis on the signal they received. The satellite in question is stationed in a geostationary equatorial orbit but shifts slightly north and south. This relative movement results in a frequency shift depending on if the satellite was moving toward or away from the transmission source at time of transmission/receipt. They corroborated this analysis with signals received at the same time from known transmitters (other airplanes talking to this satellite). The result indicated that the signal originated from the southern direction.
That's clever. Thank you.
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      04-02-2014, 02:15 PM   #268
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^ this why people should pay attention to Math and Science in school. The engineers worked on it for 6 days before they figure it out.

If it was not for those pings, no one would have clue where the plane is. Whether they can actually find it, is different matter all together. From the sound of it, all the debris they keep seeing on satellite images and from the search planes is all the junk we dump into the ocean now of it appears to have come from the actually plane.

jwzimm did a nice job of explaining, here is a video on the subject

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      04-02-2014, 03:38 PM   #269
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^Yeah, what can I say, I am a bit of a nerd.

That video isn't exactly accurate either though. They assumed the satellite was in perfect geosync orbit (nope). The Doppler effect of the airplane moving would be so small that it's not likely to be detectable as the airplanes relative speed is quite low. It could also be deceptive as the airplane could be moving toward the satellite but still be to the north.

INMARSAT took advantage of the known motions of the satellite itself in their analysis as it's movement was much faster and would produce a more pronounced Doppler shift. It is also a known quantity that it could verify with other known emitters.
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      04-02-2014, 04:25 PM   #270
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yes I have read that the satellite itself wobbles in its orbit so it tends to swing north to south and east to west.

The long and short of it of it all, they know the broadcast frequency of transmit device, and it appears they recorded the frequency that was received by the satellite, they corrected for the satellite wobble and could then tell if the plane was getting closer or further away by the shift in the frequency from the known transmit frequency.

Here is the physics

http://physicsbuzz.physicscentral.co...nd-flight.html

For those who are interesting in understanding how hard it is going to be to locate this plane. You can read about the air France plane that when down in the Atlantic. The keep factor in finding that plane in 12,000 Ft of water was the fact they knew within 5 days about where the plane was, and they had submarine there with US military high tech listening devices and they actually recorded the pings from the blackbox in the days following and analyzed the data later and was able to go back months later and pin point the locate with side sweeping sonars. The Blackbox is running out of power and once they happens they have no chance of using those listening devices to find the pings.

http://en.wikipedia.org/wiki/Air_France_Flight_447

With all the theory out there, this guy is the most crediable source, he know the operations of the plane and how all the systems work as well investigate other crashes. He is basically saying what the authorities already know but have not been willing to say publicly.

http://leehamnews.com/2014/03/31/mh3...-investigator/

Last edited by Maestro; 04-03-2014 at 07:45 AM.
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      04-02-2014, 07:50 PM   #271
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Quote:
Originally Posted by Soorena View Post
Correct me if i'm wrong, but authorities believe that the plane crashed in ocean near Perth only if the plane's flight path was the southern arc that Inmarsat provided. How they ruled out the northern arc path?

This is the arcs i'm referring to:
Neither of those arcs is the flight path. Those arcs represent the possible location of the plane when it was last pinged by Inmarsat.

They are NOT flight paths.
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      04-02-2014, 09:52 PM   #272
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I don't get how the last possible location is delineated by the one continous arc - is it just ONE ping so they cannot triangulate the location.. or what?
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      04-03-2014, 06:49 AM   #273
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I don't get how the last possible location is delineated by the one continous arc - is it just ONE ping so they cannot triangulate the location.. or what?
Yes, the sat is in geostationary orbit so the red arcs represent the possible location of the plane based on a single ping.

Since then, the company has examined previous pings as well as some doppler information which puts the plane in the area where the search is now taking place.

I'm driven mad however by people, including TV pundits, stating that the red arcs are possible flight paths. They are not.
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      04-04-2014, 01:51 PM   #274
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here is more information from the satellite company itself, these are the guys who figure it out.

http://www.inmarsat.com/news/malaysi...tails-uk-aaib/
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      04-04-2014, 05:00 PM   #275
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highly doubt they will find this plane anytime soon. even they find the debris, it's probably hundred if not thousand miles away from the crash site. the black box is most likely out of battery by now. whatever it is, i just hope all the families will get an answer asap
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