The present invention relates to a system and method for determining a vital sign of a subject. To improve the detection of electromagnetic radiation reflected from or transmitted through skin of a subject (110) at least two differently modulated radiation sources (112, 114) are used. For both camera and single-element sensors, this allows access (after demodulation) to different mixtures of skin and non-skin reflections/transmissions that can be de-mixed and successively allows the skin-only signal to be used for photoplethysmography, PPG, extraction. Thus, a sensor (130) detects the reflected or transmitted electromagnetic radiation and a demodulation unit (140) and processing unit (150) enable to determine a vital sign (160) from said detection signal.
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