[time-nuts] MH370 Doppler

[Joe Leikhim]

The L Band uplink was reported to be transmitting at around 1.6435/ghz.
/
Assuming, we actually knew what the  tolerance of the OCXO (If it is an 
OCXO) was under the environment of the mishap, and assuming it /was/ 
10ppm for example. The  error would be  (1,650 X1,000,000) * 10ppm or 
_16,500 hz_. I think we can discount the error being that large, but 
could still rationalize it being a significant portion of the reported 
BFO value./
/
Also the ground track is unknown, they are attempting to reconstruct the 
ground track from the BFO (Burst Frequency Offset "Doppler") and from 
the BTO (timing pings) the BTO supposedly offers range information, 
hence the concentric rings corresponding to pings._

_

_Chris Alb__ertson wrote:_

"The total Doppler in this case is on the order of 100 Hz.   The tiny
frequency shifts of an out of spec OCXO is just to small to measure.
The data says at UTC 18:30 the shift was in the mid range and was
about 175Hz.       Assume the OCXO drifts 10 parts per million.  That
is a lot for an OCXO.  But maybe the effect is only about 50 feet on
the ground.

The OCXO error of even 1E-5 is just not very important as it does not
move the aircrafts ground track enough to matter."


-- 
Joe Leikhim


Leikhim and Associates

Communications Consultants

Oviedo, Florida

JLeikhim at Leikhim.com

407-982-0446

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