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Pinpointing plane by calculating ping time differences [New Straits Time (Malaysia)]
[April 08, 2014]

Pinpointing plane by calculating ping time differences [New Straits Time (Malaysia)]


(New Straits Time (Malaysia) Via Acquire Media NewsEdge) INMARSAT-3F1 is a satellite in geosynchronous orbit (GEO) launched in 1996 to provide telephone and data services worldwide.

The satellite is 35,800km above the equator at a longitude of 64.5o. The satellite orbits the Earth every 23 hours, 56 minutes and 4 seconds.

It covers Africa, Asia and part of Australia.

At the time of the last "ping", the Inmarsat-3F1 satellite had an orbital inclination (the angle between a reference plane and another plane or axis of direction) of 1.7o.

GEO satellites have a 0o inclination angle but gradually drifts north-south daily because of the influence of the sun and moon.

According space scientist Duncan Steele, when MH370 took off from Kuala Lumpur International Airport, Inmarsat-3F1 was at a declination angle of approximately 1.2o and at the time of the final "ping" the satellite was at a declination of about 0.6o. Pings travel at a certain frequency range.



The movement of MH370 changes the frequency and these changes will inform you of the movement of the aircraft, which is known as the Doppler Effect.

The difference between the expected received frequency and the actual measured one due to the Doppler Effect is known as Burst Frequency Offset. This information was used to generate arcs of possible positions.


To validate the results behind this, Inmarsat obtained information from six other Boeing 777 aircraft flying on the same day and found good agreement.

The final ping, which was an incomplete ping that appears just eight minutes after the last hourly ping was transmitted to the satellite, could inform investigators of the precise time the aircraft lost its ability to communicate and this will help narrow the search area.

Dr Mandeep Singh, Department of Electrical, Electronic and System Engineering, Universiti Kebangsaan Malaysia (c) 2014 ProQuest Information and Learning Company; All Rights Reserved.

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