Optical Rangefinding Trace Accumulation for Weak Signal Detection
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Solution Overview
Problem
Conventional optical rangefinders face challenges in accurately measuring distance and resolving signal noise ratio, particularly in adverse weather conditions, due to limitations in existing digital processing techniques that do not adapt to varying range-dependent needs.
Innovation Solution
The system employs a method involving a light source, optical detector, and analog-to-digital converter to generate an accumulated digital trace through phase shifting and accumulation techniques, allowing for improved resolution and signal-to-noise ratio by combining multiple traces and increasing the effective sample rate, enabling better detection in various weather conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If averaging technique is used to improve signal to noise ratio, then signal to noise ratio is improved, but response time increases and system becomes too slow
Solution Approach 1:
The patent divides the signal processing into multiple segments by acquiring multiple traces and accumulating them. This segmentation allows the system to process signals in discrete units that can be independently accumulated, improving signal-to-noise ratio while maintaining response time through efficient parallel processing of the segmented data.
Solution Approach 2:
The patent employs periodic acquisition of multiple traces at defined intervals, accumulating them systematically. This periodic action creates a structured approach where noise averages out over time while maintaining a predictable response rate, resolving the contradiction between noise reduction and response time.
2Measurement precision
If clock pulse delay circuit technique with integer division is used to enhance resolution, then distance measurement resolution is improved by factor N, but number of averages required increases when averaging technique is also used
Solution Approach 1:
The patent replaces the traditional clock pulse delay circuit technique with a digital processing approach using multiple trace accumulation. Instead of using hardware delay circuits and integer division to achieve resolution enhancement, the system uses software-based accumulation of multiple traces, which achieves similar resolution improvement without increasing device complexity or requiring additional averages.
Solution Approach 2:
The patent changes the processing parameter from time-delay-based resolution enhancement to accumulation-based resolution enhancement. By accumulating multiple traces and analyzing the combined signal, the system achieves high resolution without needing complex delay circuits or increasing the number of averages, thus resolving the contradiction between measurement precision and device complexity.
3Reliability
If conventional threshold-based detection is used, then false alarms from transient noise can be avoided by setting threshold high, but objects returning weak signal reflection cannot be detected
Solution Approach 1:
The patent merges multiple individual trace detections into a single accumulated trace. By combining the information from multiple traces, the system enhances weak signals through constructive accumulation while noise tends to cancel out. This merging approach allows detection of weak reflections without increasing false alarms, as the accumulated signal provides stronger evidence for genuine detections.
Solution Approach 2:
The patent uses feedback from multiple trace acquisitions to improve detection reliability. Each trace provides feedback information that is accumulated and used to refine the final detection decision. This feedback mechanism allows the system to distinguish between genuine weak signals and noise more effectively, resolving the contradiction between false alarm rejection and weak signal detection.
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 detection and measurement of object distance while optimizing performance parameters like resolution and repetition rate, effectively improving accuracy and reliability in different applications, including adverse weather conditions.
Implementation Method 1
detecting a reflection signal of the pulse by the optical detector
Implementation Method 2
determine the distance to the object from the propagation delay value; measuring the time a short pulse of light emitted from the apparatus takes to reach an object and be reflected
Data Source
AI summary
There is provided a system and a method for acquiring a detected light optical signal and generating an accumulated digital trace The method comprises providing a light source for illumination of a field of view, an optical detector, an analog-to-digital converter (ADC), emitting one pulse from the light source in the field of view, detecting a reflection signal of the pulse by the optical detector, acquiring j points for the detected reflection signal by the ADC, storing, in a buffer, the digital signal waveform of j points, introducing a phase shift of 2pi / P, repeating, P times, the steps of emitting, detecting, acquiring, storing and introducing, to store, in the buffer, an interleaved waveform of P x j points, accumulating M traces of interleaved P x j points for a total of N = M x P acquisition sets, N being a total number of pulses emitted, creating one combined trace of the reflected signal of j x P points by adding each point of the M traces Additionally, the combined trace can be compared to a detected reference reflection signal of the pulse to determine a distance traveled by the pulse