Looking at the RF currents on the power line from a digital LED panel. The noise from the PWM switching is all sub-5MHz, and noise from the communication bus / internal state updates runs from 1MHz to 100MHz. The measurement numbers were not corrected and are only useful for relative comparisons.
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The goal here was to determine what kind of filtering the board needed- it looks like a few hundred uF of bulk capacitors does a good job for the 0-3MHz PWM noise, and series resistors on the communication cable reduces the higher frequency bits by 5-15dB.
