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Re: Where Does Doppler Occur?



Before bringing out out too much Special Relativity to describe
this issue, remember that the Doppler Effect also happens with
sound waves, to which relativity does not apply.  Also, unlike
electromagnetic radiation, sound has an absolute frame of
reference: the air through which it travels. 

Doug
NA1DB

At 04:21 PM 12/1/01 , you wrote:

>My question is meaningless, too, without a reference frame. In the reference frame of the satellite (neglecting its orbital acceleration) the frequency is exactly the frequency it was transmitted with. In the reference frame of, say, the Sun, it's something else. And of course in the reference frame of the ground station it's some other value. Which of these is the "real" frequency? They are all equally real. This is starting to get philosophical.
>
>For most practical purposes, we can set aside all this confusing relativism and just pick a convenient reference frame for all our calculations. For this example, let's pick the reference frame in which the mass center of the Earth is fixed. (We'll neglect gravitational accelerations due to the Sun, Moon, and other celestial bodies.) That's a convenient reference frame for computation of the main effects on a satellite -- satellite tracking programs use it.

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