| CPC G01S 7/4865 (2013.01) [G01B 11/26 (2013.01); G01S 7/4808 (2013.01); G01S 7/497 (2013.01); G01S 17/36 (2013.01); G01S 17/46 (2013.01); G01S 17/89 (2013.01); G01S 17/894 (2020.01)] | 20 Claims |

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1. A phase angle error calculation apparatus for an optical ranging system, the apparatus comprising:
a light source configured to emit light in accordance with an indirect time of flight measurement technique;
a photonic mixer cell configured to generate and store a plurality of electrical output signals respectively corresponding to a plurality of predetermined phase offset values applied in accordance with the indirect time of flight measurement technique over a measurement cycle; and
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 reference vector and a reference phase angle from the reference vector, the plurality of electrical output signals corresponding to measurement at a first level of precision; wherein
the signal processing circuit is configured to process a subset of electrical output signals from the plurality of electrical output signals in accordance with the indirect time of flight measurement technique in order to calculate a measurement vector and a measurement phase angle from the measurement vector, the subset of the electrical output signals corresponding to measurement at a second level of precision lower than the first level of precision; and
the signal processing circuit is configured to calculate a phase angle correction value using the reference phase angle and the measurement phase angle.
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