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sci.geo.satellite-nav (Global Satellite Navigation) (sci.geo.satellite-nav) Discussion of global navigation satellite systems (GNSS). Topics include the technical aspects of GNSS operation, user experiences in the use of GNSS, information regarding GNSS products and discussion of GNSS policy (such as GPS selective availability).

MH 370 Inmarsat Positioning



 
 
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  #1  
Old March 23rd 14, 03:47 PM posted to sci.geo.satellite-nav
Happy Trails
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Posts: 341
Default MH 370 Inmarsat Positioning


For the first time I am seeing a reference to usage of Inmarsat data
directly in a news article.

http://www.nytimes.com/2014/03/23/wo...=68973199&_r=0

It is significant that this article quotes an Inmarsat executive as
indicating the receipt of hourly pings from MH370 not only at the IOR
satellite, but also at a ground station they have in Perth, and that
enabled them to more accurately infer where the plane might have been
at the time.

The article does not however elaborate on how this was estimated,
other than using "trigonometry"!

  #2  
Old March 23rd 14, 04:05 PM posted to sci.geo.satellite-nav
Alan Browne
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Posts: 1,339
Default MH 370 Inmarsat Positioning

On 2014.03.23, 11:47 , Happy Trails wrote:

For the first time I am seeing a reference to usage of Inmarsat data
directly in a news article.

http://www.nytimes.com/2014/03/23/wo...=68973199&_r=0

It is significant that this article quotes an Inmarsat executive as
indicating the receipt of hourly pings from MH370 not only at the IOR
satellite, but also at a ground station they have in Perth, and that
enabled them to more accurately infer where the plane might have been
at the time.

The article does not however elaborate on how this was estimated,
other than using "trigonometry"!


Good ref. Thanks. "Trigonometry" is involved no matter what source data
is used... (power, elevation, lateration-projection).

--
Privacy has become an essential personal chore that most
people are not trained to perform.
- Jaron Lanier, Scientific American, 2013.11.

  #3  
Old March 23rd 14, 06:04 PM posted to sci.geo.satellite-nav
Happy Trails
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Posts: 341
Default MH 370 Inmarsat Positioning

On Sun, 23 Mar 2014 17:55:34 +0000, Jeff wrote:

It does not say "*also* at a ground station they have in Perth" it says
" between Flight 370, a satellite over the Indian Ocean and a ground
station in Perth, Australia" which I read as the pings being received in
Perth *via* the satellite.


Jeff, you can misread it any way you want. I do not have the patience
nor the interest to give you a reading lesson via usenet.

  #4  
Old March 23rd 14, 06:05 PM posted to sci.geo.satellite-nav
Alan Browne
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Posts: 1,339
Default MH 370 Inmarsat Positioning

On 2014.03.23, 13:55 , Jeff wrote:

It is significant that this article quotes an Inmarsat executive as
indicating the receipt of hourly pings from MH370 not only at the IOR
satellite, but also at a ground station they have in Perth, and that
enabled them to more accurately infer where the plane might have been
at the time.


It does not say "*also* at a ground station they have in Perth" it says
" between Flight 370, a satellite over the Indian Ocean and a ground
station in Perth, Australia" which I read as the pings being received in
Perth *via* the satellite.


I agree.

It is possible for a station in Perth to get the aircraft signal
directly, but it would almost certainly have to be in line-of-sight to
the aircraft.

Given the distance of the "arcs" from Perth almost certainly not.


--
... it may be that "in the cloud" really isn't the best term
for the services these companies offer. What they really
want is to have us "on the leash."
-David Pogue, Scientific American, 2014.02
  #5  
Old March 23rd 14, 06:07 PM posted to sci.geo.satellite-nav
Alan Browne
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Posts: 1,339
Default MH 370 Inmarsat Positioning

On 2014.03.23, 14:05 , Alan Browne wrote:
On 2014.03.23, 13:55 , Jeff wrote:

It is significant that this article quotes an Inmarsat executive as
indicating the receipt of hourly pings from MH370 not only at the IOR
satellite, but also at a ground station they have in Perth, and that
enabled them to more accurately infer where the plane might have been
at the time.


It does not say "*also* at a ground station they have in Perth" it says
" between Flight 370, a satellite over the Indian Ocean and a ground
station in Perth, Australia" which I read as the pings being received in
Perth *via* the satellite.


I agree.

It is possible for a station in Perth to get the aircraft signal
directly, but it would almost certainly have to be in line-of-sight to
the aircraft.

Given the distance of the "arcs" from Perth almost certainly not.


Correction:
Given the distance of the "arcs" from Perth, certainly not.

--
Those who have reduced our privacy, whether they are state
or commercial actors, prefer that we do not reduce theirs.
- Jaron Lanier, Scientific American, 2013.11.

  #6  
Old March 23rd 14, 06:16 PM posted to sci.geo.satellite-nav
Alan Browne
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Posts: 1,339
Default MH 370 Inmarsat Positioning

On 2014.03.23, 14:04 , Happy Trails wrote:
On Sun, 23 Mar 2014 17:55:34 +0000, Jeff wrote:

It does not say "*also* at a ground station they have in Perth" it says
" between Flight 370, a satellite over the Indian Ocean and a ground
station in Perth, Australia" which I read as the pings being received in
Perth *via* the satellite.


Jeff, you can misread it any way you want. I do not have the patience
nor the interest to give you a reading lesson via usenet.


L1 (INMARSAT) is line of sight.

The distance from Perth to the arcs, even considering aircraft altitude,
is too far to have been received directly from the aircraft.

At an altitude of 39,000 feet, the LOS distance is over 200 NM. The arc
is over 1000 NM from Perth.


--
Privacy has become an essential personal chore that most
people are not trained to perform.
- Jaron Lanier, Scientific American, 2013.11.

  #7  
Old March 23rd 14, 09:36 PM posted to sci.geo.satellite-nav
Happy Trails
external usenet poster
 
Posts: 341
Default MH 370 Inmarsat Positioning

On Sun, 23 Mar 2014 17:55:34 +0000, Jeff wrote:

It does not say "*also* at a ground station they have in Perth" it says
" between Flight 370, a satellite over the Indian Ocean and a ground
station in Perth, Australia" which I read as the pings being received in
Perth *via* the satellite.


Jeff,

I apologize. I guess I am the one who needs the reading lesson.

Of course the data was only "found" at the ground station in Perth -
they would have no data retention facility elsewhere, like on the
satellite, would they!

I was just too eager to jump all over your head for continually
dragging the darn cellphone networks into the conversation as if they
were relevant or something.

 




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