Analog Pulse Pile-Up Rejection Using Timing Comparison
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Solution Overview
Problem
Current methods for addressing pulse pile-up distortion in signal detection systems, such as those used in nuclear medicine and astrophysics, are inefficient due to high power consumption and complexity, particularly in high-density channel applications or those with limited power budgets, and often require additional ADC and off-line processing.
Innovation Solution
An apparatus and method for pulse pile-up rejection using a delay value application and comparison constituents to determine pulse acceptance or rejection based on peak-occurrence time values, implemented in Application-Specific Integrated Circuits (ASICs), which calculates an adjustable delay value from time jitter and walk values to minimize distortion and increase sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital signal processing methods are used to correct pulse pile-up distortion, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts only the essential timing information (threshold-crossing time and peak-occurrence time) from the pulse signal, rather than processing the entire pulse waveform digitally. By isolating and comparing these specific time parameters, the system achieves pile-up rejection without requiring complex digital signal processing of the full signal, thus reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent performs preliminary timing measurements by detecting threshold-crossing times and peak-occurrence times before any pile-up correction is needed. These preliminary time stamps are stored and later used to identify and reject piled-up pulses, eliminating the need for complex post-acquisition digital processing and reducing overall system complexity.
2Measurement precision
If additional ADC and off-line processing are used to address pulse pile-up, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The system uses its own existing timing measurement capabilities (threshold-crossing detection and peak-detection circuits) to perform pile-up rejection, rather than requiring additional ADC converters and off-line processing resources. The timing information already captured for spectral analysis is reused for pile-up identification, making the system self-sufficient and avoiding additional power-consuming components.
3Measurement precision
If complex pile-up correction algorithms are implemented, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent changes the approach from complex algorithmic correction to simple parameter comparison. By transforming the pile-up detection problem into a straightforward comparison of time parameters (threshold-crossing time versus peak-occurrence time), the system achieves high measurement precision through simple operational logic that is easy to implement and operate.
Data Source
AI summary
A method and apparatus for pulse pile-up rejection are disclosed. The apparatus comprises a delay value application constituent configured to receive a threshold-crossing time value, and provide an adjustable value according to a delay value and the threshold-crossing time value; and a comparison constituent configured to receive a peak-occurrence time value and the adjustable value, compare the peak-occurrence time value with the adjustable value, indicate pulse acceptance if the peak-occurrence time value is less than or equal to the adjustable value, and indicate pulse rejection if the peak-occurrence time value is greater than the adjustable value.