LIDAR ADC Gain Control for Long-Range Dynamic Range
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Solution Overview
Problem
Light detection and ranging (LIDAR) systems face signal loss issues due to distance, which limit their effective dynamic range and require high data rates and power consumption in data interfaces between the analog-to-digital converter (ADC) and signal processor.
Innovation Solution
An ADC system with a digitally programmable gain stage and control circuit adjusts gain settings based on elapsed time from a laser firing instance to compensate for signal loss on a sample-by-sample basis, increasing the effective dynamic range and reducing data rate and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the LIDAR system uses a fixed gain ADC system, then the system structure is simple, but the effective dynamic range is limited due to signal loss over distance
Solution Approach 1:
The patent implements a time-varying gain structure where the ADC gain is dynamically adjusted based on the elapsed time since laser firing. The control circuit receives a trigger signal at the laser firing instance and generates gain settings that vary with time, transforming the static ADC system into a dynamic one that adapts to the changing signal characteristics over the measurement range.
Solution Approach 2:
The patent changes the gain parameter of the ADC system as a function of time elapsed since laser firing. The control circuit outputs gain settings that are based on elapsed time from the laser firing instance, allowing the system to optimize its dynamic range for different distances by adjusting this critical parameter.
2Measurement precision
If the LIDAR system uses a high dynamic range data interface to support full range specifications, then the measurement range is extended, but the data rate and power consumption increase
Solution Approach 1:
The patent applies dynamic gain adjustment to match the signal characteristics at different time points, allowing the ADC to operate at optimal resolution for each time window. This dynamic adaptation reduces the need for excessively high data rates across the entire measurement range, as each time segment uses only the resolution necessary for that specific range.
Solution Approach 2:
By changing the gain parameter over time based on elapsed time from laser firing, the system optimizes the signal amplitude for each time window, reducing the dynamic range requirements of the data interface and subsequently lowering power consumption and data rate requirements.
3Loss of information
If the LIDAR system uses a high data rate interface to maintain full dynamic range, then the signal fidelity is preserved, but the power consumption and system complexity increase
Solution Approach 1:
The time-varying gain structure ensures that the signal is optimized for each time window, maintaining signal fidelity without requiring uniformly high data rates across all ranges. The control circuit dynamically adjusts gain settings based on elapsed time, preserving information while reducing overall data interface requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the dynamic range of the ADC system, reduces data rate and power consumption, and eliminates the need for the data interface to support the full dynamic range, improving the efficiency of LIDAR systems.
Implementation Method 1
an ADC circuit configured to generate a representation of a light pulse
Implementation Method 2
a digitally programmable digital gain stage coupled to an output of the ADC circuit or an ADC full scale adjustment circuit coupled to an input of the ADC circuit, the gain stage having a gain to modify the representation of the light pulse
Data Source
AI summary
Techniques to adjust a gain of an analog-to-digital converter circuit (ADC) and/or an ADC full scale from one sample to the next of an analog input signal to compensate for the signal loss over distance, which can increase an effective dynamic range of the system. The benefit of compensating for the signal loss due to distance is that a data interface between the ADC of the receiver of the LIDAR system and a signal processor no longer needs to support the dynamic range from the range specification.