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US 7,405,812 B1Granted
Method and system to avoid inter-system interference for phase-based time-of-flight systems
AssigneeCanesta, Inc.
InventorCyrus Bamji
Life of this patent
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AssigneeCanesta, Inc.
InventorCyrus Bamji
Estimating the term…
Inter-system interference cross-produce P12 is 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 P12 without substantially affecting TOF system performance.
In a first time-of-flight (TOF) detection system that emits time modulated optical energy and examines phase shift in a fraction of said optical energy reflected by a target object to determine distance Z therebetween, a method of reducing potential interference from an adjacent second TOF system also emitting optical energy, the method comprising:
For use with a time-of-flight (TOF) homodyning detection system of the type that emits time modulated optical energy and examines phase shift in a fraction of said optical energy reflected by a target object to determine distance Z therebetween, a clock system that reduces potential interference from an adjacent second TOF system also emitting optical energy, the clock system comprising:
For use with a first time-of-flight (TOF) detection system of the type that emits modulated optical energy and examines phase shift in a fraction of said optical energy reflected by a target object to determine distance Z therebetween, a clock system that reduces potential interference from an adjacent second TOF system also emitting optical energy, the clock system comprising:
Dependencies are inferred from the claim text.