Spreading sequences performance on time-of-flight smart pixels

Time-of-Flight cameras deals with distance measurements in a matrix, pixel by pixel. Every pixel, called smart pixel, makes use of analog technology to calculate correlations, and in such a way, it computes the phase difference between the emitted signal and the received one, both modulated in RF-range. The main drawback of these systems is their short working range, that depends on the wavelength of the modulating signal. This problem can be overcome by using a multi-camera system with different modulating frequencies, but then, the performance is adversely affected because of interference phenomena. One approach to deal with this situation consist of encoding the emissions with spreading sequences that exhibit good cross-correlations properties among them. The number of possible cameras depends on the correlations properties of the sequences. In this work, the performance of spreading sequences in terms of bandwidth and signal-to-noise ratio used in time-of-flight systems is presented. Kasami sequences are considered to be a good choice for multi-camera environment.