[amsat-bb] Re: Malaysian airliner puzzle
michael.bd5rv at gmail.com
Mon Mar 17 08:05:15 PDT 2014
The distance calculated between the satellite and the plane won't be
credible if the time on both are not synchronized, even if the
transmission from the plane is time tagged. As a matter of fact, it's
quite difficult to keep such an synchronization.
Michael Chen, BD5RV/4
Email: michael.bd5rv at gmail.com
MSN: bd5rv at jsdxc.org
On Mon, Mar 17, 2014 at 4:27 AM, James Duffey <jamesduffey at comcast.net> wrote:
> I think that the transmissions from the airplane are time tagged, even without the data packets being transmitted. By comparing the ping time to the time on the satellite, one can tell how far away the ping is. You can draw a circle with that radius, taking into account fuel available on the airplane and last heading to sort of kind of bound where the airplane is. That is where the red circles in the NY Times article come from.
> A second satellite is needed to pinpoint a more exact location, but even that will have a relatively position error on the ground. I don't think it is within range of another INMARSAT. Whether or not other assets exist that could receive the signal is a matter of speculation. - KK6MC
> On Mar 16, 2014, at 2:01 PM, Rick Walter <wb3csy at gmail.com> wrote:
>> Tony, since the satellite cannot tell direction of the Ping, only distance, the arcs have the same distance from the plane making up a half circle. You would need to sats to hear the plane, see where the two arcs cross to determine a location.
>> This is the same way seismic stations locate earthquakes.
>> Rick - WB3CSY
>> Sent from Rick's iPhone 5
>> "Great spirits have always encountered violent opposition from mediocre minds" - Albert Einstein
>>> On Mar 16, 2014, at 12:24 PM, "Anthony Japha" <ajapha at earthlink.net> wrote:
>>> Those so-called arcs that are said to be possible routes for the plane look much like the outer edge of one of the Inmarsat footprints. Is there logic behind the arcs or is it oversimplified nonsense? They are said to be the result of the signals Inmarsat received. But then why wouldn't it be possible for the plane to be anywhere in the footprint?
>>> I'm sure many in our group have good ideas. I'm not trying to start a discussion of the entire mystery, only this one narrow, but possibly misleading, aspect related to our hobby.
>>> Tony, N2UN
>>> LM 183
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