Reducing interference in an active illumination environment
Apparatuses, systems and methods are disclosed for reducing interference between an active illumination device and external radiation sources, for example, other active illumination devices operating within the vicinity. A disclosed system includes one or more active illumination devices, each configured to emit an illumination signal and also to receive a returned portion of its respective illumination signal with at least one sensor. At least one of the active illumination devices is capable of detecting interference caused by an external source, for example, an illumination signal emitted from another active illumination device. As a result of detecting the interference, the receiving active illumination device changes the timing of its subsequent illumination signals and sensor operation. By detecting collisions between illumination signals and consequently altering the timing of it operation, the active illumination device may reduce interference in congested environments where multiple active illumination devices are operating within range of each other.
1. An apparatus, comprising:
a compass;
an illuminator;
an image sensor; and
a processor, operatively coupled to the image sensor and the illuminator, the processor configured to:
detect interference in one or more signals received by the image sensor;
determine a direction of travel of the apparatus based on one or more readings from the compass; and
change the timing of an illumination signal of the illuminator as a result of detecting the interference and based on the direction of travel of the apparatus.
2. The apparatus of claim 1 , wherein the interference is caused by an illumination signal emitted by an active illumination device.
3. The apparatus of claim 1 , wherein the processor is configured to detect the interference by:
determining one or more intensity values for one or more pixels included in the image sensor;
comparing the intensity values to at least one intensity threshold value; and
detecting the interference if a predetermine number of intensity values exceeds the intensity threshold value.
4. The apparatus of claim 1 , wherein the illumination signal is periodic.
5. The apparatus of claim 1 , wherein the processor is further configured to advance or retard the timing of the illumination signal.
6. The apparatus of claim 1 , wherein the processor is configured to select a start time for the illumination signal by applying a randomizing function to a predetermined value associated with the apparatus.
7. The apparatus of claim 1 , wherein the processor is further configured to spatially resolve an image location of the interference.
8. The apparatus of claim 1 , further comprising a modulator to provide the one or more signals by modulating, as a function of time, received light reflected from a scene in response to the illumination signal, and wherein the processor is further configured to determine a 3D range based on the one or more signals.
9. The apparatus of claim 1 , wherein the processor is configured to detect the interference without the illuminator first emitting the illumination signal that would otherwise be detectable.
10. The apparatus of claim 1 , wherein the illuminator is configured to generate the illumination signal for flash LIDAR.