Distance sensing by IQ domain differentiation of time of flight (TOF) measurements

摘要

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.

主权项

1. A method for use with a system that includes an optical sensor and that is configured to determine at least one of a distance or presence of one or more moving objects relative to the optical sensor, the method comprising:
(a) driving a light emitting element with a drive signal to thereby cause a light signal to be emitted; (b) producing 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; (c) performing quadrature demodulation of the sensor signal to produce in-phase (I) and quadrature phase (Q) signals; (d) determining derivatives of the in-phase (I) and quadrature-phase (Q) signals; and (e) determining a phase of the derivatives of the in-phase (I) and quadrature-phase (Q) signals.