These diagrams are licensed under CC-BY 4.0. So yes, you can use them in a thesis / paper / blog post, as long as you follow the CC-BY rules.
Comparison between ACS (dotted), FTF (dashed) and PFB 8-tap Hann windowed PFB filter responses.
Effect of applying a windowing function to an FFT. The main lobe is broadened but the sidelobes are supressed.
Block diagram showing a FIR filter.
The diagram shows an input signal being divided into M taps, each with P points. Within each tap, the signal is multiplied by the filter coefficients, then a sum across taps is performed. After this, another P points are read, and the signals propagate left-to-right into the next tap (following the arrows).
Streaming DSP style diagram showing the PFB frontend connected to a FFT to form a polyphase filerbank.
Diagram showing scalloping loss between channels of a spectrometer
Another way of looking at taking filter coefficients and breaking them into subfilters.
The Wiener-Khinchin relation, and how it relates to spectrometers to compute the PSD.
Windowing functions and their magnitude squared filter response (i.e. spectrometer channel shape).