Vintage ? Doppler Shift ? Tech Helps Track Malaysian Airlines MH370

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Vintage ? Doppler Shift ? Tech Helps Track Malaysian Airlines MH370


The tragedy of Malaysian Airlines Flight MH370 is filled with a myriad of emotions and questions. Everyday, news about the missing plane, the relatives of the passengers, and the efforts of the world community to try and locate the aircraft is eagerly awaited.

So far, not even a single shred of debris or evidence has been recovered and analyzed to confirm that Flight MH370 has indeed gone down. The authorities concerned, however, have practically ruled that the plane has more or less crashed and that no one has survived.

This 2 week old saga may just see an end to all this mystery because of a method that a group of engineers has developed in order to hasten the tracking and recovery of the plane.

Far from being ?groundbreaking? as some thought, the technology used in calculating the flight path of Malaysian Airlines MH370 has been around for the past 30 ++ years.

This tracking method, which has been used even before the advent of Global Positioning Systems (GPS), is providing the search teams valuable information to narrow the scope of the area to focus on.

And what is this ?vintage? technology?

The Engineers are referring to it as a ?Doppler Shift Tracking? method, and here is how it works.

Even if an aircraft, like the Malaysian Airlines jet, is not able to send any communications during certain hours of its flight, it can still keep on sending a signal to a communications company called Inmarsat.

Inmarsat operates a satellite and provides communication services to various airline and shipping companies. It is considered to be one of the biggest such operators of satellite services in the world.

In regular intervals, the satellite and a ship or plane establish contact with each other by pinging, providing a ?handshake signal? that would inform both points that they can communicate with each other.

Even if an aircraft like Flight MH370 does not send any concrete communication to the satellite, it still continues to ?ping? and this emits a frequency.

This frequency signal, in a form of a wave is then subjected to some basic laws of physics, in this case, the Doppler shift.

And what is a Doppler shift?

Wikipedia defines the Doppler shift or also known as the Doppler effect as follows: ? The Doppler effect, named after the Austrian physicist Christian Doppler, who proposed it in 1842 in Prague, is the change in frequency of a wave for an observer moving relative to its source. It is commonly heard when a vehicle sounding a?siren?or horn approaches, passes, and recedes from an observer. Compared to the emitted frequency, the received frequency is higher during the approach, identical at the instant of passing by, and lower during the recession. ?

This ?effect? is commonly experienced during a race like the NASCAR. If one closes his eyes, this person still knows when a speeding race car is approaching and when it is running past just by listening to the sound of the car’s loud engines.

Greg Durgin, a teacher at Georgia Tech on satellite communications, relates this to the Malaysian Airlines tragedy by explaining that ? We know how fast planes travel and we knew the bearing of the course relative to the Inmarsat satellite.? He added that with this information and with the Doppler-effect pings with the Inmarsat satellite, ?we can infer a lot about the position of the aircraft.? (Note: Durgin is not connected to Inmarsat and the search operations. )

This method was what the engineers at Inmarsat utilized in order to determine the path of Flight MH370. They noted the shift in the frequency of the ping sent by the airline and backtracked it to its location.

Many are wondering why this technology, which was already in use when American scientists were able to track Sputnik when it launched in 1957, was used as a last resort in trying to locate the missing aircraft.

Durgin speculated that InMarsat primarily uses their satellite for networking and communication purposes and it took a while for the engineers to accumulate the proper data to make a ?Doppler estimate?, as well as create the needed algorithms and formulas to process the data. He adds that ?The type of satellite they were using to receive these pings wasn?t designed to do geolocation…..The engineers deserve a lot of credit for their foresight to even give it the capability to do this.?


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