Laser Range Finder Noise Compensation via Signal Correlation
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Solution Overview
Problem
Existing laser range finders face challenges in accurately measuring long distances due to noise errors in echoed signals, which affect the determination of phase shifts and thus the accuracy of distance measurements.
Innovation Solution
A system and method that utilize a correlator to normalize the amplitude of the transmitted signal to match the reflected signal, employing cross-correlation techniques to calculate the phase shift between the transmitted and reflected signals, and using a polarizing splitter to average signals with different polarizations to reduce noise errors, allowing for more accurate distance calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If cross-correlation method is used to determine phase shift, then measurement range is extended to long distances, but measurement precision deteriorates due to noise errors in echoed signals
Solution Approach 1:
The patent introduces an intermediary signal processing step between the echoed signal and the correlation calculation. A reference signal is generated and used to correlate with the echoed signal, serving as a mediator that enhances the extraction of phase shift information from noisy long-range echoes. This intermediary reference signal allows the system to achieve both long measurement range and high precision by providing a stable comparison baseline.
Solution Approach 2:
The system implements feedback through iterative correlation processing where the determined phase shift is used to adjust and refine subsequent measurements. The correlation results feed back into the system to improve the accuracy of phase shift determination, creating a closed-loop measurement process that compensates for noise errors and enhances precision in long-range measurements.
2Measurement precision
If time of flight method is used for direct measurement, then measurement precision is improved, but device complexity increases due to requirement of fast electronics
Solution Approach 1:
The patent replaces the direct time-of-flight measurement approach with an indirect phase shift measurement method. Instead of using fast electronics to directly measure the time of flight, the system uses phase modulation and correlation techniques that can be implemented with simpler, slower electronics. The phase shift of the modulated signal carries the time information, allowing measurement of long distances without requiring ultra-fast electronic timing circuits.
3Ease of operation
If periodic signal analysis is used, then ease of operation is improved, but measurement range is limited to short or medium distances
Solution Approach 1:
The patent employs dynamic signal processing where the correlation window and reference signal are adaptively adjusted based on the expected time of flight. The system dynamically modifies the analysis parameters to optimize for different range conditions, allowing the simple periodic signal analysis to effectively measure long distances by adapting the time base and correlation parameters to the specific measurement scenario.
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
The system provides improved accuracy in measuring long distances by compensating for noise errors and simplifying the system structure, enabling more precise phase shift determination and distance measurement.
Implementation Method 1
using a polarizing splitter to average signals with different polarizations to reduce noise errors
Data Source
AI summary
A system and method is described for determining a distance to a desired target via correlating a pulse modulated signal with its corresponding reflected signal, while compensating for noise error in the reflected signal to allow for a more precise distance determination. Further details and features are described herein.