Figure 1.

Diagram showing frequency domain processing by a set of DNNs indexed by frequency, k. N is the number of elements in the receive subaperture. s_n(t) is the gated data for the nth channel. The input signals are a single gated depth of channel data. A discrete Fourier transform (DFT) transformed each channel signal into the frequency domain. $\Re$ indicates the real component and $\Im$ indicates the imaginary component. Processed frequency domain data is transformed back into the time domain using an inverse discrete Fourier transform (IDFT) (Yang 2008).