Patent ID: 8398557

Claim:
An apparatus for determining a physiological parameter of a living being, comprising: a receiver adapted to receive iterating optical signals, an optical signal comprising sequences, and a sequence comprising at least two bright periods during which a transmit light source adopts an on state and at least two dark periods during which no transmit light source adopts an on state, and the at least two bright periods being irregularly arranged within a sequence, and an extractor for extracting information on the physiological parameter from the receive signal, the extractor being adapted either to receive, to store or to generate binary code words comprising a length and indicating an arrangement of the bright and dark periods, and to link a binary code word with the signals in a block-by-block manner so as to obtain a digital signal of a bright transmit channel, the bright transmit channel being determined by the binary code word, and to link two other binary code words with the signals so as to obtain two digital signals of two dark transmit channels which are determined by the two other binary code words, and the extractor being adapted to extract, on the basis of the digital signal of the bright transmit channel and of the two digital signals of the dark transmit channels, a value of a magnitude indicating the physiological parameter, the extractor being implemented to form a differential signal from the two dark transmit channels, and to reduce an aliasing interference in the digital signal of the bright transmit channel by means of a spectral analysis of the differential signal.