Doppler Effect

observed frequency f and

emitted frequency f0 is given by :..

where

$f = \left( \frac{c + v_r}{c + v_{s}} \right) f_0 \,$

$c \;$

is the velocity of waves in the medium

is the velocity of the receiver relative to the medium; positive if the receiver is moving towards the source.

is the velocity of the source relative to the medium; positive if the source is moving away from the receiver.

$v_{r} \,$

$v_{s} \,$