The Australian ship Ocean Shield has detected multiple pings from the black boxes onboard the missing Malaysia Airline Flight 370, specifically on 4 lines of bearing according to this article. The same article also states that they need a few more lines of bearing in order to further narrow down the search area.

So my question is pretty much as in the title - can they use doppler shift to help figure out where the pings are coming from? IIRC, they used the doppler shift from the satellite data to figure out that the aircraft was most likely on the southern of the two arcs that were proposed several weeks ago.


1 Answer 1


Doppler shift occurs only when the sender, the receiver or both are moving relatively to each other. As the black boxes rest at the bottom of the ocean and the search ships move relatively slow, there won't be any significant Doppler shift. However, if the Ocean Shield receives several signals at different locations (the location of the Ocean Shield), the position of the black box can be triangulated.

The Doppler shift from the signals the satellites received was most probably used to determine the speed of MH370 to extrapolate the most likely area in which the plane might have gone down.

  • $\begingroup$ So you're saying there's not enough of a difference in speed to use the doppler shift reliably? How fast would Ocean Shield need to be moving to use doppler? $\endgroup$
    – Nickolai
    Apr 9, 2014 at 15:12
  • $\begingroup$ @Nickolai If you use the standard equation for frequency shift as a function of relative closing velocity, you'll see a ship would need fantastically precisie frequency measurement, and even aircraft would have to be rather close to see a measurable shift. $\endgroup$ Apr 9, 2014 at 15:17
  • $\begingroup$ Moreover, if the search ship would be able to extract a Doppler shift from the received signals, the only information gained would be the velocity of the ships. As we are save to assume that the black box is not moving, any Doppler shift would be caused by the ships motion. $\endgroup$
    – Dohn Joe
    Apr 9, 2014 at 15:37
  • $\begingroup$ Furthermore, the only information that can be extracted from a Doppler shift is the relative velocity between sender and receiver. $\endgroup$
    – Dohn Joe
    Apr 9, 2014 at 15:38
  • 2
    $\begingroup$ @DohnJoe But if (in theory) you tracked the Doppler frequency as a function of your position, you can determine the rate of angular change of position and thus find the source. Easier in the lab than in the ocean :-) $\endgroup$ Apr 9, 2014 at 16:32

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