NEAR RANGE OBJECT DETECTION

1 . A system, comprising:

a light source configured to emit an output beam comprising a plurality of light pulses through a window;

a receiver, wherein the receiver is configured to detect a reference signal, the reference signal corresponding to one of the plurality of light pulses reflected from the window, and wherein the receiver is configured to detect a received signal, the received signal comprising a signal portion corresponding to one of the plurality of light pulses scattered by a target located at a distance; and

a processor configured to determine the distance to the target using the received signal, including by being configured to subtract the reference signal from the received signal.

2 . The system of claim 1 , wherein the receiver is configured to:

detect the reference signal in response to a trigger of a reference signal extraction phase.

3 . The system of claim 2 , wherein the reference signal extraction phase comprises one of the following: a system initialization phase, a periodic phase over time, or a phase triggered by a temperature drift.

4 . The system of claim 3 , wherein the processor is configured to:

disable the reference signal extraction phase in response to detecting an object.

5 . The system of claim 1 , wherein the processor is configured to:

update the reference signal, comprising:

detecting an additional signal by the receiver, wherein the additional signal corresponds to another one of the plurality of light pulses reflected from the window; and

updating the reference signal at least in part based on a statistical measure of the reference signal and the additional signal.

6 . The system of claim 1 , wherein the receiver is configured to:

filter the reference signal including by applying a filtering window around a peak of a pulse in the reference signal, wherein a width of the filtering window is at least in part based on a width of the pulse.

7 . The system of claim 1 , wherein the receiver is configured to:

temporally shift the reference signal in response to a detected jitter in the received signal prior to subtracting the reference signal from the received signal.

8 . The system of claim 7 , wherein the processor is configured to:

align a rising edge of a peak of a pulse in the reference signal with a rising edge of a peak of a pulse in the received signal.

9 . The system of claim 1 , wherein the processor is further configured to:

in response to determining that the distance to the target is within a predetermined threshold range, determine that the target comprises a blockage on the window.

10 . The system of claim 9 , wherein the processor is further configured to:

determine a type of the blockage on the window at least in part based on one or more of the following: a size, a width, a magnitude, a power level, or an energy level of a peak in the received signal that corresponds to the blockage on the window.

11 . The system of claim 10 , wherein the received signal comprises a second signal portion corresponding to one of the plurality of light pulses scattered by a second target located at a second distance, the processor is configured to:

determine the second distance to the second target after the reference signal is subtracted from the received signal;

in response to determining that the second distance is above the predetermined threshold range, determine that the second target is a downrange object; and

determine the type of the blockage on the window at least in part based on one or more of the following: a size, a width, a magnitude, a power level, or an energy level of a second peak in the received signal that corresponds to the second target.

12 . The system of claim 9 , wherein the processor is configured to:

provide an indication of a type of the blockage on the window.

13 . The system of claim 1 , wherein the processor is configured to:

superimpose a copy of the reference signal shifted by a predetermined time offset to the reference signal to form a modified version of the reference signal, wherein the reference signal subtracted from the received signal is the modified version of the reference signal.

14 . The system of claim 13 , wherein the predetermined time offset is determined based on a time period between two of the plurality of light pulses that are consecutive to each other.

15 . A method, comprising:

emitting an output beam comprising a plurality of light pulses through a window;

detecting a reference signal by a receiver, wherein the reference signal corresponds to one of the plurality of light pulses reflected from the window;

detecting a received signal by the receiver, wherein the received signal comprises a signal portion corresponding to one of the plurality of light pulses scattered by a target located at a distance; and

determining, by a processor, the distance to the target using the received signal, including by subtracting the reference signal from the received signal.

16 . The method of claim 15 , further comprising:

filtering the reference signal including by applying a filtering window around a peak of a pulse in the reference signal, wherein a width of the filtering window is at least in part based on a width of the pulse.

17 . The method of claim 15 , further comprising:

temporally shifting the reference signal in response to a detected jitter in the received signal prior to subtracting the reference signal from the received signal.

18 . The method of claim 15 , further comprising:

in response to determining that the distance to the target is within a predetermined threshold range, determining that the target comprises a blockage on the window.

19 . The method of claim 18 , further comprising:

determining a type of the blockage on the window at least in part based on one or more of the following: a size, a width, a magnitude, a power level, or an energy level of a peak in the received signal that corresponds to the blockage on the window.

20 . A system, comprising:

a light source configured to emit an output beam comprising a plurality of light pulses through a window;

a receiver, wherein the receiver is configured to detect a reference signal, the reference signal corresponding to one of the plurality of light pulses reflected from the window, and wherein the receiver is configured to detect a received signal, the received signal comprising a signal portion corresponding to one of the plurality of light pulses scattered by a target located at a distance; and

a processor configured to:

determine a compensating signal by adding a copy of the reference signal that is shifted by a predetermined time offset to the reference signal; and

determine the distance to the target using the received signal, including by being configured to subtract the compensating signal from the received signal.