A physiological parameter sensing system, comprising: a sensing interface adapted to obtain at least two detection signals derived from detected electromagnetic radiation reflected from, or transmitted through, a skin region of a subject's body; a heart rate sensing means; and a processor, operatively coupled with the sensing interface and heart rate sensing means and adapted to: control the heart rate sensing means to acquire a heart rate signal, the heart rate signal being distinct from the detection signals; derive at least two pulse signals, each formed from a weighted combination of the detection signals, wherein weightings for each pulse signal are based on components of a different one of a set of at least two blood volume pulse vectors; derive, using the heart rate signal, a quality indicator value for each derived pulse signal, the quality indicator value being based on a characteristic of a derived relationship between the pulse signal and the heart rate signal of the subject, sensed by the heart rate sensing means; and derive physiological information indicative of at least one physiological parameter from the blood volume pulse vector resulting in the pulse signal having the highest quality indicator value and/or from the derived pulse signal itself, wherein the quality indicator value for each derived pulse signal is derived based on determining a strength of correlation between the pulse signal and the heart rate signal, or a signal derived from the heart rate signal. a sensing interface adapted to obtain at least two detection signals derived from detected electromagnetic radiation reflected from, or transmitted through, a skin region of a subject's body; a heart rate sensing means; and a processor, operatively coupled with the sensing interface and heart rate sensing means and adapted to: control the heart rate sensing means to acquire a heart rate signal, the heart rate signal being distinct from the detection signals; derive at least two pulse signals, each formed from a weighted combination of the detection signals, wherein weightings for each pulse signal are based on components of a different one of a set of at least two blood volume pulse vectors; derive, using the heart rate signal, a quality indicator value for each derived pulse signal, the quality indicator value being based on a characteristic of a derived relationship between the pulse signal and the heart rate signal of the subject, sensed by the heart rate sensing means; and derive physiological information indicative of at least one physiological parameter from the blood volume pulse vector resulting in the pulse signal having the highest quality indicator value and/or from the derived pulse signal itself, control the heart rate sensing means to acquire a heart rate signal, the heart rate signal being distinct from the detection signals; derive at least two pulse signals, each formed from a weighted combination of the detection signals, wherein weightings for each pulse signal are based on components of a different one of a set of at least two blood volume pulse vectors; derive, using the heart rate signal, a quality indicator value for each derived pulse signal, the quality indicator value being based on a characteristic of a derived relationship between the pulse signal and the heart rate signal of the subject, sensed by the heart rate sensing means; and derive physiological information indicative of at least one physiological parameter from the blood volume pulse vector resulting in the pulse signal having the highest quality indicator value and/or from the derived pulse signal itself, wherein the quality indicator value for each derived pulse signal is derived based on determining a strength of correlation between the pulse signal and the heart rate signal, or a signal derived from the heart rate signal.