Device , system and method for obtaining a vital signal of a subject

In an approach to obtaining vital signs of a subject, a subject monitoring device obtains at least two detection signals acquired from a subject that are related to a physiological property of the subject and allows extraction of a vital sign of the subject. The subject monitoring device performs a spectral decomposition of the at least two detection signals to obtain two or more spectral components of the detection signals and determines a weight per spectral component based on an estimate of the relevance. The subject monitoring device determines a weight value by determining at least one of a variance of the spectral component and a standard deviation of the spectral component and determines whether at least one of the variance and the standard deviation exceed a predetermined limit. Responsive to determining that at least one of the variance and the standard deviation do not exceed the predetermined limit, the subject monitoring device setts the weight to a weight value of 1 and extracts the weighted vital sign of the subject.