MTI RNAV

A Moving Target Indicator uses Doppler effect. By displaying only those targets that have returned pulses that having changed frequency, it displays only those targets that are moving relative to the transmitter. As the ground is not moving, this will now be ignored and not displayed.

Note that an unwelcome side effect of this is that aircraft with tangential movement (meaning the pulses that return from them will also not have a change in frequency) will also not be displayed.