TOF WRAPAROUND MITIGATION AND EME REDUCTION
According to an embodiment, a method to mitigate target wraparound in time-of-flight is proposed. The method includes extending the system's pulse interval to include predetermined and dynamic blanking times. The dynamic blanking time is increased by an offset at each successive pulse. The dynamic blanking time is reset in response to reaching a predetermined dynamic blanking time. The dynamic blanking time is initially set to zero. The method further includes processing events within an active window to measure a time interval between the transmission of a pulse and the receipt of a reflected pulse from an object. The duration of the active window is equal to the duration of the initial pulse interval. The method further includes ignoring events within an inactive window, a duration of the inactive window corresponding to the duration of the extended pulse interval minus the duration of the active window.
1 . A method to mitigate target wraparound in a time-of-flight system, the method comprising:
extending a pulse interval of the time-of-flight system from a first pulse interval to a second pulse interval to include a predetermined blanking time;
extending the second pulse interval of the time-of-flight system to a third pulse interval to include a dynamic blanking time, wherein the dynamic blanking time is increased by an offset at each successive pulse, wherein, in response to the dynamic blanking time reaching a predetermined dynamic blanking time, the dynamic blanking time is reset, and wherein the dynamic blanking time is initially set to zero;
processing events by the time-of-flight system within an active window to measure a time interval between a transmission of a pulse and receipt of a reflected pulse from an object by the time-of-flight system, a duration of the active window equal to a duration of the first pulse interval; and
ignoring events within an inactive window, a duration of the inactive window corresponding to a duration of the third pulse interval minus the duration of the active window.
2 . The method of claim 1 , wherein the first pulse interval corresponds to a time interval for a light pulse to travel from a light source of the time-of-flight system to a target at a furthest measurable distance of the time-of-flight system and return to a photodetector of the time-of-flight system.
3 . The method of claim 1 , wherein one or more of the predetermined blanking time, the offset, and the predetermined dynamic blanking time are configurable.
4 . The method of claim 1 , wherein the events within the inactive window are registered by photodetectors of the time-of-flight system but ignored during the processing.
5 . The method of claim 1 , wherein the events within the inactive window are not registered by photodetectors of the time-of-flight system.
6 . The method of claim 1 , further comprising calculating a distance between a device hosting the time-of-flight system and the object based on the time interval.
7 . The method of claim 1 , wherein the offset forms a triangular dynamic pattern over time.
8 . A method to mitigate electromagnetic emissions in a time-of-flight system, the method comprising:
extending a pulse interval of the time-of-flight system from a first pulse interval to a second pulse interval to include a predetermined blanking time;
extending the second pulse interval of the time-of-flight system to a third pulse interval to include a dynamic blanking time, wherein the dynamic blanking time is increased by an offset at each successive pulse, wherein, in response to the dynamic blanking time reaching a predetermined dynamic blanking time, the dynamic blanking time is reset, and wherein the dynamic blanking time is initially set to zero;
employing a spread spectrum frequency modulation to a clock signal used for timing of pulses at each pulse interval;
processing events by the time-of-flight system within an active window to measure a time interval between a transmission of a pulse and receipt of a reflected pulse from an object by the time-of-flight system, a duration of the active window equal to a duration of the first pulse interval; and
ignoring events within an inactive window, a duration of the inactive window corresponding to a duration of the third pulse interval minus the duration of the active window.
9 . The method of claim 8 , wherein the first pulse interval corresponds to a time interval for a light pulse to travel from a light source of the time-of-flight system to a target at a furthest measurable distance of the time-of-flight system and return to a photodetector of the time-of-flight system.
10 . The method of claim 8 , wherein employing the spread spectrum frequency modulation comprises spreading a center frequency of the clock signal across a frequency spectrum within a set window.
11 . The method of claim 10 , wherein one or more of the predetermined blanking time, the offset, the predetermined dynamic blanking time, and the set window are configurable.
12 . The method of claim 8 , wherein the events within the inactive window are registered by photodetectors of the time-of-flight system but ignored during the processing.
13 . The method of claim 8 , wherein the events within the inactive window are not registered by photodetectors of the time-of-flight system.
14 . The method of claim 8 , further comprising calculating a distance between a device hosting the time-of-flight system and the object based on the time interval.
15 . A time-of-flight system, comprising:
a non-transitory memory storage comprising instructions; and
a processor in communication with the non-transitory memory storage, wherein the instructions, when executed by the processor, cause the time-of-flight system to:
extend a pulse interval of the time-of-flight system from a first pulse interval to a second pulse interval to include a predetermined blanking time,
extend the second pulse interval of the time-of-flight system to a third pulse interval to include a dynamic blanking time, wherein the dynamic blanking time is increased by an offset at each successive pulse, wherein, in response to the dynamic blanking time reaching a predetermined dynamic blanking time, the dynamic blanking time is reset, and wherein the dynamic blanking time is initially set to zero,
employ a spread spectrum frequency modulation to a clock signal used for timing of pulses at each pulse interval, and
process events by the time-of-flight system within an active window to measure a time interval between a transmission of a pulse and receipt of a reflected pulse from an object by the time-of-flight system, a duration of the active window equal to a duration of the first pulse interval, wherein events within an inactive window are ignored, a duration of the inactive window corresponding to a duration of the third pulse interval minus the duration of the active window.
16 . The time-of-flight system of claim 15 , wherein the first pulse interval corresponds to a time interval for a light pulse to travel from a light source of the time-of-flight system to a target at a furthest measurable distance of the time-of-flight system and return to a photodetector of the time-of-flight system.
17 . The time-of-flight system of claim 15 , wherein employing the spread spectrum frequency modulation comprises spreading a center frequency of the clock signal across a frequency spectrum within a set window.
18 . The time-of-flight system of claim 17 , wherein one or more of the predetermined blanking time, the offset, the predetermined dynamic blanking time, and the set window are configurable.
19 . The time-of-flight system of claim 15 , wherein the events within the inactive window are registered by photodetectors of the time-of-flight system but ignored during the processing.
20 . The time-of-flight system of claim 15 , wherein the events within the inactive window are not registered by photodetectors of the time-of-flight system.