A-line profiles of three scatterers at different depths for a modulation frequency of 688.8 kHz (=16* f A - 2.4). A combination of all three scatterers is shown at the bottom. The Fourier components at F ( ω 0 − ω m ), corresponding to a depth z 0 − z m , consists of three peaks: the vibration signal (negative sideband) originated from the scatterer at ω 0 or z 0 in depth (scatterer 1); the time-independent reflection signal (carrier signal) from a scatterer at depth z 0 − z m (scatterer 2); and the vibration signal (positive sideband) originated from the scatterer located at z 0 − 2 z m (scatterer 3). f A : A-line rate, ω 0 : center wavenumber, ω m : angular frequency of the vibration signal, δ : vibration amplitude.
