Optical spread spectrum detection and ranging

1. A system comprising:

a light emitter configured to emit a light signal;

a line-image sensor configured to receive reflected light signals at a plurality of positions along the line-image sensor; and

a controller communicatively coupled to the light emitter and the line-image sensor, the controller being configured to determine whether a given reflected light signal received at the line-image sensor is a multi-path signal based on (i) an amount of time between emission of the light signal from the light emitter and reception at the line-image sensor of the given reflected light signal, and (ii) a position along the line-image sensor at which the line-image sensor received the given reflected light signal;

wherein the controller is configured to determine that the given reflected light signal is a multi-path signal by:

determining the position along the line-image sensor at which the line-image sensor received the given reflected light signal;

based on the determined position, calculating a target window of time subsequent to emission of the light signal; and

determining that the line-image sensor received the given reflected light signal at a time outside of the target window of time;

wherein the line-image sensor has a proximate end and a distal end, the light emitter being positioned nearer to the proximate end than the distal end, and

wherein the target window of time is a length of time subsequent to emission of the light signal, the length of time being proportionate to a distance from the proximate end of the line-image sensor to the determined position along the line-image sensor at which the line-image sensor received the given reflected light signal.

2. The system of claim 1 ,

wherein the light emitter is configured to emit a plurality of light signals that reflect off of an obstacle and return to the line-image sensor as the reflected light signals, and

wherein the controller is configured to estimate a distance from the line-image sensor to the obstacle based on a set of reflected light signals, wherein signals determined to be multi path signals are excluded from the set.

3. The system of claim 1 , wherein the light emitter and the line-image sensor are mounted on a rotatable component.

4. The system of claim 3 , further comprising a motor configured to apply torque to the rotatable component.

5. The system of claim 1 , wherein the light emitter is further configured to emit light signals in accordance with a particular pseudo-noise (PN) code, and wherein the system further comprises:

a filter configured to filter out reflected light signals emitted in accordance with a PN code other than the particular PN code.

6. The system of claim 5 , wherein the controller is further configured to determine the amount of time between emission of the light signal from the light emitter and reception at the line-image sensor of the given reflected light signal by correlating a PN code of the emitted light signal with a PN code of the reflected light signal and, based on the correlation, determining how much the PN code of the reflected light signal is delayed relative to the PN code of the emitted light signal.

7. The system of claim 1 , wherein the emitted light signal comprises a PN sequence component and a beacon component, and wherein the system further comprises:

a shutter system configured to activate and deactivate a shutter that blocks at least a portion of the line-image sensor from receiving the reflected light signal, wherein the shutter system is further configured to time the activation and deactivation of the shutter based on receipt of the beacon component of the emitted light signal.

8. A method comprising:

emitting a light signal from a light emitter in accordance with a particular pseudo-noise (PN) code, wherein the light signal comprises a plurality of light signals that reflect off of an obstacle and return to the line-image sensor as reflected light signals;

receiving a reflection of the emitted light signal, wherein the reflection of the emitted light signal is received at a position along a line-image sensor;

determining whether the reflection of the emitted light signal received at the line-image sensor is a multi-path signal based on (i) an amount of time between emission of the light signal and reception at the line-image sensor of the reflection of the emitted light signal, and (ii) the position along the line-image sensor at which the line-image sensor received the reflection of the emitted light signal;

estimating a distance from the line-image sensor to the obstacle based on a set of reflected light signals, wherein signals determined to be multi path signals are excluded from the set;

correlating a received plurality of lights signals to the particular PN code, and

controlling a shutter to filter out reflected light signals emitted in accordance with a PN code other than the particular PN code; and

determining the amount of time between emission of the light signal from the light emitter and reception at the line-image sensor of the given reflected light signal by determining how much the particular PN code of the reflected light signal is delayed relative to the particular PN code of the emitted light signal.

9. A collision avoidance system, comprising:

an inertial measurement unit configured to measure rotation and acceleration of a vehicle about one or more axes of the vehicle;

an obstacle detection unit comprising:

a light emitter configured to emit a plurality of light signals;

a line-image sensor configured to receive reflected light signals at a plurality of positions along the line-image sensor, wherein the reflected light signals comprise a reflection off of an obstacle of at least one of the plurality of light signals; and

a controller communicatively coupled to the light emitter and the line-image sensor, the controller being configured to determine whether a given reflected light signal received at the line-image sensor is a multi-path signal based on (i) an amount of time between emission of the light signal from the light emitter and reception at the line-image sensor of the given reflected light signal, and (ii) a position along the line-image sensor at which the line-image sensor received the given reflected light signal; and

a control system, wherein the control system is communicatively coupled with the inertial measurement unit and the obstacle detection unit, and wherein the control system is configured to control the vehicle to avoid detected objects by sending control outputs to the vehicle based on information received from the inertial measurement unit and the obstacle detection unit;

wherein the controller is further configured to estimate a distance from the line-image sensor to the obstacle based on a set of reflected light signals, wherein signals determined to be multi path signals are excluded from the set; and

wherein the light emitter is further configured to emit light signals in accordance with a particular pseudo-noise (PN) code, and wherein the control system is further configured to filter out reflected light signals emitted in accordance with a PN code other than the particular PN code.

10. The system of claim 9 , wherein the controller is further configured to determine the amount of time between emission of the light signal from the light emitter and reception at the line-image sensor of the given reflected light signal by correlating a PN code of the emitted light signal with a PN code of the reflected light signal and, based on the correlation, determining how much the PN code of the reflected light signal is delayed relative to the PN code of the emitted light signal.