Systems and methods for efficient multi-return light detectors
Described herein are systems and methods that may efficiently detect multi-return light signals. A light detection and ranging system, such as a LIDAR system, may fire a laser beam that may hit multiple objects with a different distance in one line, causing multi-return light signals to be received by the system. Multi-return detectors may be able to analyze the peak magnitude of a plurality of peaks in the return signals and determine a multitude of peaks, such as the first peak, the last peak and the maximum peak. One embodiment to detect the multi-return light signals may be a multi-return recursive matched filter detector. This detector comprises a matched filter, peak detector, centroid calculation and a zeroing out function. Other embodiments may be based on a maximum finder that algorithmically selects the highest magnitude peaks from samples of the return signal and buffers for regions of interests peaks.
1. A multiple-return light signal detection method for a light detection and ranging (LIDAR) system, the method comprising:
receiving a multi-return signal having a plurality of peaks in a time period;
filtering the multi-return signal based, at least in part, on a pulse shape of an emitted laser beam, to produce a filtered signal;
identifying a largest peak of the filtered signal in the time period;
eliminating the largest peak from the filtered signal;
and detecting a peak hidden in a blinding spot occurring temporally after the largest peak.
2. The method of claim 1 further comprising emitting the laser beam prior to receiving the multi-return signal.
3. The method of claim 1 , wherein filtering the multi-return signal comprises convolving the multi-return signal with a signal having the pulse shape of the emitted laser beam.
4. The method of claim 1 , wherein detecting a peak hidden in a blinding spot comprises:
selecting and storing samples for a plurality of regions of interest for the sequence of two or more peaks in the time period; and
zeroing out a contribution of a waveform of the largest peak using the samples for the regions of interest.
5. A light detection and ranging (LIDAR) system comprising:
one or more signal processing components configured to:
receive a multi-return signal having a plurality of peaks in a time period;
filter the multi-return signal based, at least in part, on a pulse shape of an emitted laser beam, to produce a filtered signal; identify a largest peak of the filtered signal in the time period;
eliminate the largest peak from the filtered signal; and
detect a peak hidden in a blinding spot occurring temporally after the largest peak.
6. The system of claim 5 further comprising a transmitter configured to emit the laser beam prior to receiving the multi-return signal.
7. The system of claim 5 , wherein filtering the multi-return signal comprises convolving the multi-return signal with a signal having the pulse shape of the emitted laser beam.
8. The system of claim 5 , wherein, detecting a peak hidden in a blinding spot comprises:
selecting and storing samples for a plurality of regions of interest for the sequence of two or more peaks in the time period; and
zeroing out a contribution of a waveform of the largest peak using the samples for the regions of interest.