Patent ID: 9325920
Filing Date: 2016-04-26
CPC Classification: G01S,H04N

Claim Text:
1. A method of determining the presence of aliasing or avoiding aliasing within certain limits in correlation measurements in a time-of-flight system having an imaging sensor and being for use with an illumination unit, the illumination unit being adapted to illuminate a scene with modulated light, the system being adapted to obtain correlation measurements between a correlation signal and modulated light reflected from the scene, the method comprising: a) detecting reflected light from at least one object in the scene; b) determining by one or more first correlation measurements a first correlation between a first correlation signal and the reflected light received at the imaging sensor the first correlation signal having a periodic waveform of a first frequency and the first correlation measurement providing a value of a parameter related to a distance from the imaging sensor to the at least one object; c) determining by one or more second correlation measurements a second correlation between the reflected light received at the imaging sensor and a second correlation signal, the second correlation signal having a periodic waveform of a second frequency lower than the first frequency; d) determining for that value of the parameter the presence of aliasing from the second correlation measurement, and wherein the first and/or second correlation measurements are combined into aliasing indicators, the presence of aliasing is determined from indicators being the sign of the in-phase and/or quadrature components of the detected reflected light.