TDC Delay Correction for Voltage Drop in Distance Measurement
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Solution Overview
Problem
Distance measuring apparatuses face accuracy issues due to voltage drop variations during calibration operations, which affect the delay elements in TDC circuits, leading to potential measurement errors during distance measurement operations.
Innovation Solution
A TDC apparatus with a delay circuit, storage elements, an edge detection unit, and a delay amount correction unit that generates a delay conversion table and corrects delay times using a specific equation to account for voltage drop variations, ensuring accurate distance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If calibration operation is performed by continuously inputting a large number of pulses in a short period, then calibration speed is improved, but voltage drop variation increases causing delay element accuracy to deteriorate
Solution Approach 1:
The patent applies preliminary action by measuring the voltage drop during calibration operation in advance, storing it in a voltage drop storage unit, and then using this pre-measured value to correct delay amounts during subsequent distance measurement operations. This allows the system to perform fast calibration without compromising measurement accuracy, as the voltage drop information is captured beforehand and reused.
Solution Approach 2:
The patent implements feedback by using the measured voltage drop value from calibration operation to correct the delay amounts during distance measurement. The correction unit adjusts the delay amounts based on the stored voltage drop information, creating a feedback loop that compensates for voltage variations and maintains measurement precision across different operating conditions.
2Measurement precision
If delay amount correction is performed based on calibration data, then measurement accuracy is improved, but device complexity increases due to additional correction units and voltage drop storage
Solution Approach 1:
The patent merges the voltage drop measurement function with the existing calibration operation. The voltage drop measurement unit operates during the same calibration period when delay elements are already being tested, combining two measurement functions into one operational phase. This reduces overall system complexity by eliminating separate measurement periods and integrating multiple functions into unified operational sequences.
Data Source
AI summary
A TDC apparatus includes a TDC circuit having a delay circuit including a plurality of stages of delay elements configured to sequentially delay a measurement signal and a plurality of storage elements configured to respectively hold outputs of the plurality of stages of delay elements in response to a measurement clock input thereto; an edge detection unit that detects at least a rising edge of the measurement signal based on switching of the outputs of the plurality of storage elements; and a delay amount correction unit configured to output a delay time of the measurement signal whose delay amount has been corrected by adding or subtracting a correction delay amount to or from a delay amount corresponding to the detection stage of the delay element in a delay conversion table relating to the detection stage of the delay element and a delay amount of the plurality of delay elements.