An electronic monitoring device includes an electronic processor (620) having at least one signal input for body monitoring, and a memory (630) holding instructions for the electronic processor coupled to the electronic processor so that the electronic processor is operable to isolate a cardiac signal including cardiac pulses combined with other cardiac signal variations, and the electronic processor further operable to execute a filter (730) that separates a varying blood flow signal from the cardiac pulses and to output information (790) based on at least the varying blood flow signal. Other devices, sensor assemblies, electronic circuit units, and processes are also disclosed.