Frequency band division of the QTT ultrawideband low-frequency system. The 704–4032 MHz range is split into three analog bands (704–1344, 1344–2368, and 2368–4032 MHz), each sampled by a separate RFSoC board. Dashed lines mark the first and second Nyquist zones for the two sampling rates (Fs = 2560 and 4096 MHz). Sub-bands (SB1-SB26) produced by the 4/3 oversampled polyphase filter bank are indicated along the frequency axis.