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1.3. Signal Processing Algorithm Overview
The conceptual overview of the sensor signal processing algorithm is shown in Figure 4:
Figure 4
: Leddar™ Signal Processing Algorithm Overview
1.3.1.
Signal Acquisition
The signal acquisition module samples the signal of the photodiode element using a patented
oversampling and accumulation strategy to maximize the signal resolution and the signal to noise
ratio. It provides the light intensity received by the sensor as a function of the time (corresponding
to distance knowing the speed of light) also called full-waveform signal. This full-waveform signal
allows the use of advanced signal processing techniques to extract the distances of the objects
and other useful information about the scene.
1.3.2.
Static Noise Removal
The static noise removal algorithm removes, as its name indicates, the static noise in the full-
waveform signal induced by undesirable light reflections due to sensor enclosure or
electromagnetic interferences. This algorithm increases drastically the distance measurement
accuracy and linearity. The static noise shape is learned during a calibration procedure during
which the waveform of the signal is captured while the reception lens of the sensor is shielded
from the backscattered light. The sensor comes with a static noise factory calibration. However,
the default calibration can be updated by the user using Leddar
TM
Configurator, see Section
4.4.12 for more details.
1.3.3.
Pulse Detection
The objects in the sensor field of detection create a particular signature in the full-waveform
signal called pulses. The pulse detector analyzes the full-waveform signal in order to recognize
these pulses and compute their distance. By nature, time-of-flight sensor using full-waveform
analysis is able to detect several distinct objects with a single photodiode element.
Pulse Detector
Time-of-
Flight Raw
Data
Temperature
Compensation
Smoothing
Algorithm
Calibration Offsets
Sensor
Temperature Data
Echoes
Signal Acquisition
Thresholding
Led Intensity,
Oversampling,
Accumulation and
Number of Sample
Points
Smoothing
Parameters
Static Noise
Removal
Static Noise Template
Learned during the
Calibration Process
Accurate and
Precise Distance
Measurements
Threshold Table
Saturation
Compensation
Pulse Classifier
Saturated
Echoes
Normal
Echoes
Echoes with Significant
Magnitude
Distance Offsets from
Calibration Process
Pulse of Light
Automatic Led
Intensity Control
Summary of Contents for LeddarOne
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