<https://ee-paper.com/design-method-of-ls-band-wideband-stepped-frequency-signal-source-based-on-fpga/#primaryimage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://ee-paper.com/design-method-of-ls-band-wideband-stepped-frequency-signal-source-based-on-fpga/>