In fact, you’d need a PWM frequency of 20kHz to be worried about the cheaper 40kHz ADCs in some phones. As long as the PWM f is below that, measuring this way makes sense and works. Report comment ...

Figure 4. FFT of 4 μs-wide, 20-μs repeating linear FM chirp. Markers are placed on the FFT response, and it can be seen that this RF pulse does have a wide spectral width, from 300 MHz to 900 ...

B&K Precision’s models 2540B-GEN and 2542B-GEN digital storage oscilloscopes integrate function/arbitrary waveform generation capability into 60-MHz and 100-MHz, 1-sample/s instruments B&K ...