First 155 words of the document:
Radar or radio detection and ranging is used in air traffic control in order to
calculate the position of planes, while it is also used in weather to detect
storms. The system is based on the pulse-echo techniques used by bats and
dolphins. The time take for a known speed radio wave to be reflected it
measured, and using a simple calculation they can find the distance o
f an object. However it is not just
radar it is doppler radar because they use doppler shift to measure any
changes in the wavelength. They do this by comparing the original wave to the
echo and hence they can calculate the speed of the object.
So in summary, radar is used to calculate the distance, and doppler shift is
used to calculate the speed of the air traffic or storm movement.