Hello VLF, I attach here a SpecLab screenshot where I have found that multiple copies of the same signal are present. The signal at 21100 is probably genuine RDL, while other copies at about +/- 300H
Daniele, the signal does not really look like one of the RDL types, and I also don't think the "copies" are an aliasing artifact. My guess would be a power converter running at 21 kHz, modulated by 3