Sensor device for arrangement at a subject's body part for sensing physiological information of the subject, said sensor device comprising: - a PPG sensor for providing a photoplethysmography, PPG, signals modulated on a first set of one or more carrier signals, - a motion sensor for providing a motion reference signal representing motion of the body part, at which the sensor device is arranged, and - a device for obtaining physiological information of the subject, said device comprising: - a PPG signal input for obtaining the PPG signals, - a motion signal input for obtaining the motion reference signal, and - a processing unit for generating an output signal carrying physiological information by (i) modulating the motion reference signal on a carrier signal of the first set of carrier signals or on a second carrier signal orthogonal to the first set of carrier signals to obtain a modulated signal and combining the modulated signal with the modulated PPG signals to obtain the output signal or (ii) demodulating the modulated PPG signals, performing artifact-reduction on the demodulated PPG signals using the motion reference signal to obtain artifact-reduced PPG signals and modulating the artifact-reduced PPG signals on the first set of carrier signals to obtain the output signal. - a PPG sensor for providing a photoplethysmography, PPG, signals modulated on a first set of one or more carrier signals, - a motion sensor for providing a motion reference signal representing motion of the body part, at which the sensor device is arranged, and - a device for obtaining physiological information of the subject, said device comprising: - a PPG signal input for obtaining the PPG signals, - a motion signal input for obtaining the motion reference signal, and - a processing unit for generating an output signal carrying physiological information by (i) modulating the motion reference signal on a carrier signal of the first set of carrier signals or on a second carrier signal orthogonal to the first set of carrier signals to obtain a modulated signal and combining the modulated signal with the modulated PPG signals to obtain the output signal or (ii) demodulating the modulated PPG signals, performing artifact-reduction on the demodulated PPG signals using the motion reference signal to obtain artifact-reduced PPG signals and modulating the artifact-reduced PPG signals on the first set of carrier signals to obtain the output signal. - a PPG signal input for obtaining the PPG signals, - a motion signal input for obtaining the motion reference signal, and - a processing unit for generating an output signal carrying physiological information by (i) modulating the motion reference signal on a carrier signal of the first set of carrier signals or on a second carrier signal orthogonal to the first set of carrier signals to obtain a modulated signal and combining the modulated signal with the modulated PPG signals to obtain the output signal or (ii) demodulating the modulated PPG signals, performing artifact-reduction on the demodulated PPG signals using the motion reference signal to obtain artifact-reduced PPG signals and modulating the artifact-reduced PPG signals on the first set of carrier signals to obtain the output signal. (i) modulating the motion reference signal on a carrier signal of the first set of carrier signals or on a second carrier signal orthogonal to the first set of carrier signals to obtain a modulated signal and combining the modulated signal with the modulated PPG signals to obtain the output signal or (ii) demodulating the modulated PPG signals, performing artifact-reduction on the demodulated PPG signals using the motion reference signal to obtain artifact-reduced PPG signals and modulating the artifact-reduced PPG signals on the first set of carrier signals to obtain the output signal.