A depth imaging system comprising: a light source for emitting light over a range of modulation frequencies; an array of pixel detectors for receiving the light from the light source after reflection from an object; and a processor being configured to determine phase shift data in light of a first modulation frequency (f 1), a second modulation frequency (f 2), and a third modulation frequency (f 3) received in a first said pixel detector of the array, wherein the second modulation frequency is greater than the first modulation frequency, and wherein the third modulation frequency is greater than the first and second modulation frequencies, the processor being further configured to de-alias the phase shift data to determine a distance to the object; characterized in that: the light of the first modulation frequency is received in a first frame and not in a second frame or in a third frame, the light of the second modulation frequency is received in the second frame and not in the first frame or in the third frame, and the light of the third modulation frequency is received in the third frame and not in the first frame or in the second frame, the first, second and third frames being different from each other; the first modulation frequency is selected to have non-repeating distance values for a given measured phase shift θ ≥ 2π over a predetermined distance range; and the processor is configured to de-alias the phase shift data to determine the distance to the object by calculating, based on the phase shift data, single-frame distance values (z 1, z 2, z 3) for each of the first, second and third frames and determining, based on the single-frame distance values, a final distance value (z f) indicative of the de-aliased distance between the depth imaging system and the object as measured at the first pixel detector. a light source for emitting light over a range of modulation frequencies; an array of pixel detectors for receiving the light from the light source after reflection from an object; and a processor being configured to determine phase shift data in light of a first modulation frequency (f 1), a second modulation frequency (f 2), and a third modulation frequency (f 3) received in a first said pixel detector of the array, wherein the second modulation frequency is greater than the first modulation frequency, and wherein the third modulation frequency is greater than the first and second modulation frequencies, the processor being further configured to de-alias the phase shift data to determine a distance to the object; characterized in that: the light of the first modulation frequency is received in a first frame and not in a second frame or in a third frame, the light of the second modulation frequency is received in the second frame and not in the first frame or in the third frame, and the light of the third modulation frequency is received in the third frame and not in the first frame or in the second frame, the first, second and third frames being different from each other; the first modulation frequency is selected to have non-repeating distance values for a given measured phase shift θ ≥ 2π over a predetermined distance range; and the processor is configured to de-alias the phase shift data to determine the distance to the object by calculating, based on the phase shift data, single-frame distance values (z 1, z 2, z 3) for each of the first, second and third frames and determining, based on the single-frame distance values, a final distance value (z f) indicative of the de-aliased distance between the depth imaging system and the object as measured at the first pixel detector. the light of the first modulation frequency is received in a first frame and not in a second frame or in a third frame, the light of the second modulation frequency is received in the second frame and not in the first frame or in the third frame, and the light of the third modulation frequency is received in the third frame and not in the first frame or in the second frame, the first, second and third frames being different from each other; the first modulation frequency is selected to have non-repeating distance values for a given measured phase shift θ ≥ 2π over a predetermined distance range; and the processor is configured to de-alias the phase shift data to determine the distance to the object by calculating, based on the phase shift data, single-frame distance values (z 1, z 2, z 3) for each of the first, second and third frames and determining, based on the single-frame distance values, a final distance value (z f) indicative of the de-aliased distance between the depth imaging system and the object as measured at the first pixel detector.