[time-nuts] Aircraft ping timing

Jim Lux jimlux at earthlink.net
Wed Mar 19 23:47:20 EDT 2014

On 3/19/14 5:21 PM, Bill Hawkins wrote:
> They only got one ping from INMARSAT at 64E above the Indian Ocean.
> There was no other ping to triangulate the position.
> One ping projects a circle on the Earth. The maximum flying range of the
> plane determined the ends of the NE and SE arcs of that circle.
> The news only gets stranger as time goes on.

not time based...from what I understand it's based on a received power 
estimate, matched against antenna patterns.

Not particularly accurate.  The power measurement is probably good to 
0.2 dB (at best).  If the transmit antenna's attitude isn't in the 
nominal straight and level (e.g. plane is banking, or parked on ground, 
perhaps with a tarp placed by a overweight gentleman holding a white 
furry cat on his lab?)

I did some back of the envelopes and there's a good many 100s of km 
uncertainty in range.

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