Distance sensing by IQ domain differentiation of time of flight (TOF) measurements
First Claim
1. A method for determining at least one of a distance or presence of one or more moving objects, the method comprising:
- (a) receiving in-phase (I) and quadrature-phase (Q) signals that were produced by performing quadrature demodulation of a sensor signal indicative of a portion of a light signal that was reflected from one or more objects;
(b) determining derivatives of the in-phase (I) and quadrature-phase (Q) signals;
(c) determining a phase of the derivatives of the in-phase (I) and quadrature-phase (Q) signals; and
(d) determining at least one of a distance or presence of one or more moving objects in dependence on the phase of the derivatives of the in-phase (I) and quadrature-phase (Q) signals.
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Accused Products
Abstract
A system and method for identifying a position of a moving object, regardless of static objects present in the optical field of an active infrared (IR) proximity detector, is provided. Moreover, a modulated light emitting diode (LED) signal is captured and processed through I/Q demodulation. Specifically, the reflections received at an IR sensor are demodulated to generate in-phase (I) and quadrature phase (Q) signals and the derivative of I/Q signals is obtained to isolate motion. For example, an I/Q domain differentiator or a high pass filter is employed to calculate the derivative, which actively remove the effects of all forms of static interference. Further, the phase of the derivative I/Q signals is determined and is utilized to reconstruct the distance at which the motion occurred.
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Citations
16 Claims
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1. A method for determining at least one of a distance or presence of one or more moving objects, the method comprising:
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(a) receiving in-phase (I) and quadrature-phase (Q) signals that were produced by performing quadrature demodulation of a sensor signal indicative of a portion of a light signal that was reflected from one or more objects; (b) determining derivatives of the in-phase (I) and quadrature-phase (Q) signals; (c) determining a phase of the derivatives of the in-phase (I) and quadrature-phase (Q) signals; and (d) determining at least one of a distance or presence of one or more moving objects in dependence on the phase of the derivatives of the in-phase (I) and quadrature-phase (Q) signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 16)
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8. A subsystem for use with a further subsystem, the further subsystem including a driver configured to produce a drive signal that drives a light emitting element to thereby cause a light signal to be emitted, an optical sensor configured to produce a sensor signal that is indicative of a portion of the light signal that reflects from one or more objects and is incident on the optical sensor and a demodulator configured to perform quadrature demodulation of the sensor signal to produce in-phase (I) and quadrature phase (Q) signals, the subsystem comprising:
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a differentiator configured to determine derivatives of the in-phase (I) and quadrature phase (Q) signals from the demodulator; a phase detector configured to determine a phase of the derivatives of the in-phase (I) and quadrature phase (Q) signals; and circuitry configured to use the phase of the derivatives of the in-phase (I) and quadrature phase (Q) signals to determine at least one of a distance or presence of one or more moving objects within a sensor field of the optical sensor. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification