Particle Counter Pulse Detection Using Gradient Evaluation
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Solution Overview
Problem
Existing particle counter systems face challenges in accurately detecting signal pulses due to coincidence effects, drift behavior, and background noise, particularly when using threshold-based evaluation methods, which can lead to incorrect counting and failure to detect partially superimposed pulses.
Innovation Solution
A device with a gradient evaluation unit and a drift detection unit that evaluates the digital data stream from an AD converter, allowing for real-time detection and compensation of signal pulses and drift behavior, using parameters like minimum edge rise, rise time, and edge fall to identify pulses without requiring integrators or differentiators, and a threshold unit to filter out noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a threshold value is used to detect signal pulses, then simple detection is achieved, but coincidence effects cause overlapping pulses to be missed and drift behavior leads to incorrect counting
Solution Approach 1:
The patent changes the detection parameter from fixed threshold values to dynamic gradient values. Instead of comparing signals against a constant threshold, the system calculates the gradient (rate of change) between consecutive samples and compares this dynamic value against a threshold, enabling accurate detection of pulses regardless of drift in baseline signal levels
Solution Approach 2:
The patent introduces dynamic adaptation by continuously calculating gradients between adjacent samples. This dynamic approach allows the detection system to adapt to changing signal conditions and drift behavior in real-time, rather than relying on static threshold values that become invalid under drift conditions
2Measurement precision
If a high sampling rate is used to capture short signal pulses, then detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies partial action by using a moderate sampling rate (5-20 MSPS) rather than the extremely high rates that would be required to directly capture the full nanosecond-scale pulses. The gradient calculation method recovers pulse information from this partial sampling, achieving adequate detection without the complexity of ultra-high-speed sampling hardware
3Device complexity
If analog domain evaluation is used for signal pulses, then simplicity is maintained, but drift behavior cannot be detected and counting accuracy deteriorates
Solution Approach 1:
The patent substitutes the mechanical/analog threshold comparison method with a digital gradient calculation approach. By performing the detection in the digital domain through mathematical gradient computation rather than analog thresholding, the system gains the ability to detect and compensate for drift while maintaining computational efficiency
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
Enables accurate detection and counting of partially superimposed signal pulses, compensates for drift behavior, and filters out background noise, ensuring reliable particle counting with improved accuracy and maintenance scheduling.
Implementation Method 1
the digital data stream of the AD converter, the evaluation unit has a gradient evaluation unit that determines signal pulses in real time by evaluating the gradients between adjacent samples
Data Source
Figure 1~3
Figure 2
AI summary
The invention relates to a device for detecting signal pulses (2) in an analog measuring signal (1) of a particle counter. Said device comprises an AD converter (6) and an evaluation unit (10) that includes a slope evaluation unit (16) which determines signal pulses (2) in real time by analyzing the slopes between adjacent sampling points (8) in the digital data stream (7) of the AD converter (6).