yes I have read that the satellite itself wobbles in its orbit so it tends to swing north to south and east to west.
The long and short of it of it all, they know the broadcast frequency of transmit device, and it appears they recorded the frequency that was received by the satellite, they corrected for the satellite wobble and could then tell if the plane was getting closer or further away by the shift in the frequency from the known transmit frequency.
Here is the physics
http://physicsbuzz.physicscentral.co...nd-flight.html
For those who are interesting in understanding how hard it is going to be to locate this plane. You can read about the air France plane that when down in the Atlantic. The keep factor in finding that plane in 12,000 Ft of water was the fact they knew within 5 days about where the plane was, and they had submarine there with US military high tech listening devices and they actually recorded the pings from the blackbox in the days following and analyzed the data later and was able to go back months later and pin point the locate with side sweeping sonars. The Blackbox is running out of power and once they happens they have no chance of using those listening devices to find the pings.
http://en.wikipedia.org/wiki/Air_France_Flight_447
With all the theory out there, this guy is the most crediable source, he know the operations of the plane and how all the systems work as well investigate other crashes. He is basically saying what the authorities already know but have not been willing to say publicly.
http://leehamnews.com/2014/03/31/mh3...-investigator/