Method and system to avoid inter-system interference for phase-based time-of-flight systems

Abstract

Inter-system interference cross-produce Pis reduced in a phase-based TOF system by randomizing instantaneous phase and/or frequency within a capture interval (or detection integration period). In one aspect, the TOF clock system frequency preserves long-term clock frequency stability but intentionally includes random or pseudo-random clock noise. The noise ensures the generated clock signals are temporally imperfect and lack substantial perfect periodicity. A second aspect causes the TOF clock system to hop frequency, preferably pseudo-randomly. TOF system homodyning favors detection of optical energy whose frequency correlates to the time-varying frequency of the emitted optical energy. Thus, the varying spectral spacing of the emitted optical energy reduces likelihood that an adjacent TOF system at any given time will emit optical energy of an interfering frequency. At least one aspect is employed, both aspects being mutually complementary to reduce the cross-correlation product Pwithout substantially affecting TOF system performance.