Dithering technology to spread interference
Switch-mode type power supplies are popular because they're efficient and light weight - but also generate radio frequency interference spurs. To counter this problem the use of dithering is being used so instead of the interference remaining a fairly constant frequency or frequencies, to hops around.
With an in-built random number generator added to the power supply the RFI shifts the frequency of the emission across the RF spectrum.
from- Amateur Radio Victoria.
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