I've seen many times that a low pass filter needs to be implemented before a switching power supply in DC power line communication transceiver boards.
Why is that? I assume that the switching power supply absorbs the modulated signal, right? Would it be the same if it was a linear power supply?
Also, do all the devices that are connected to the same DC bus need to have a low pass filter? I uploaded a schematic. Would DEVICE1 and DEVICE2 need a low pass filter as the transceivers PLC1 and PLC2 do?
PLC1 and PLC2 are two devices that contain power line communication transceivers and they have a low pass filter. Device1 and Device2 are devices that might exist on the bus, for example head lights on a car, the audio system etc...