Distortion determination apparatus and method of determining a distortion

A motion or saturation determination apparatus comprising:

• a light source configured to emit light in accordance with an indirect time of flight measurement technique;
• an optoelectronic device configured to receive an electromagnetic signal and to translate the electromagnetic signal to a plurality of electrical output signals respectively corresponding to a plurality of predetermined phase offset values applied over a frame cycle in accordance with the indirect time of flight measurement technique, the optoelectronic device also being configured to store each of the plurality of electromagnetic signals;
• a signal processing circuit configured to process the plurality of electrical output signals in accordance with the indirect time of flight measurement technique in order to calculate a plurality of measurement vectors substantially in parallel and derived from the plurality of electrical output signals generated over the frame cycle, the plurality of measurement vectors being in respect of a plurality of frequencies, respectively, and comprising a first measurement vector in respect of a fundamental harmonic frequency and a second measurement vector in respect of a non-fundamental frequency;
• wherein
• the signal processing circuit is also configured to calculate a scalar relating a first amplitude of the first measurement vector to a second amplitude of the second measurement vector, and to use the scalar to identify motion or saturation in respect of the optoelectronic device over the frame cycle.