Laser Pulse Timing Offset for ADC Correlated Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser range finders face challenges in accurately measuring distances due to systematic noise introduced by Analog to Digital Converters (ADCs), which masks the detection of laser pulses, especially in long-range applications where the signal-to-noise ratio is low, and existing solutions are costly.
Innovation Solution
The implementation of a timing offset module that shifts the timing reference of each laser pulse before firing, realigns the digital codes generated by the ADC, and compares the total ADC output over a select number of clock pulses to identify reflected returns, effectively eliminating systematic clock errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If more pulses are fired and summed to improve signal-to-noise ratio, then detection accuracy improves, but systematic noise from ADC clock correlation limits the effectiveness
Solution Approach 1:
The patent applies periodic action by varying the number of ADC clock pulses used to convert analog signals to digital codes across different pulse groups. By changing the sampling period and clock pulse count systematically, the patent distributes systematic noise errors across multiple measurement cycles, preventing their correlation and enabling effective averaging to improve signal-to-noise ratio while maintaining detection accuracy
Solution Approach 2:
The patent changes the parameter of ADC clock pulse quantity across different pulse groups. By varying this parameter, the systematic noise that would normally correlate with fixed clock edges is distributed across different time windows, allowing the noise to be averaged out while preserving the target signal, thus resolving the contradiction between improving detection accuracy and eliminating systematic noise
2Measurement precision
If ADC resolution is increased to improve measurement precision, then detection accuracy improves, but cost and device complexity increase
Solution Approach 1:
Instead of increasing ADC resolution, the patent changes the operational parameters of the existing ADC by varying the number of clock pulses used for conversion across different pulse groups. This parameter-based approach achieves improved measurement precision through statistical averaging of distributed noise, avoiding the need for higher-resolution (and more complex/expensive) ADC hardware
3Measurement precision
If ADC resolution is increased to improve measurement precision, then detection accuracy improves, but cost increases
Solution Approach 1:
The patent achieves improved detection accuracy by changing the operational parameters (number of clock pulses) of a standard-resolution ADC rather than purchasing higher-resolution ADCs. This parameter-based solution maintains compatibility with existing cost-effective ADC hardware while achieving the desired measurement precision through systematic variation and averaging of noise across multiple pulse groups
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 significantly reduces systematic noise errors, allowing for more accurate detection of laser pulses and extending the range of laser range finders without the need for expensive avalanche photodiodes, by evenly distributing spurious signals across memory locations while maintaining the target return signal's linearity.
Implementation Method 1
a timing offset module that shifts the timing reference of each laser pulse in the set of pulses before the pulses are fired
Implementation Method 2
the ASIC then realigns digital codes generated by the ADC from the returned or reflected detected laser pulses. This realignment eliminates systematic clock error introduced by clock driven operation of the ADC
Implementation Method 3
Random noise is proportional to the summation of the square root of the number of pulses while the actual laser return signal varies linearly with the number of pulses
Data Source
AI summary
Error introduced by analog to digital conversion of a set of laser pulses can be reduced by shifting the clock reference time associated with the firing of the laser pulse. A timing offset module shifts the timing reference of each laser pulse. Digital codes generated by the ADC from the received signals are realigned and summed eliminating systematic error introduced by clock driven operations of the ADC. A comparison of the total ADC output of detected laser pulses over a select number of clock intervals enables a return signal to be distinguishable over the systematic error.