Editing Frequency modulation (section)

=== Doppler effect===
When an echolocating [[bat]] approaches a target, its outgoing sounds return as echoes, which are Doppler-shifted upward in frequency. In certain species of bats, which produce constant frequency (CF) [[Animal echolocation|echolocation]] calls, the bats compensate for the [[Doppler shift]] by lowering their call frequency as they approach a target. This keeps the returning echo in the same frequency range of the normal echolocation call. This dynamic frequency modulation is called the '''Doppler Shift Compensation''' (DSC), and was discovered by [[Hans Schnitzler]] in 1968.