Input Capture Counter Timing Measurement for Variable Signal Periods
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Solution Overview
Problem
Existing input capture devices face limitations in measuring the timing characteristics of input signals with variable periods, leading to low resolution and potential aliasing issues due to restricted counter clock rates to prevent rollover.
Innovation Solution
The method involves setting the counter rate to the maximum counting value divided by the delta period, allowing for precise measurement of timing characteristics by maximizing the counter's useful bandwidth and preventing aliasing, while adjusting the counter rate based on detected out-of-range periods using secondary counters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the counter rate is restricted to prevent rollover, then measurement reliability is maintained, but measurement precision deteriorates due to low resolution
Solution Approach 1:
The patent divides the measurement task into two segments: a primary counter operating at high rate for precise measurements within the expected period range, and a secondary counter operating at lower rate to detect out-of-range periods. This segmentation allows each counter to be optimized for its specific function, resolving the contradiction between reliability and precision.
Solution Approach 2:
The secondary counter acts as an intermediary that monitors for out-of-range conditions and triggers appropriate handling. It mediates between the high-rate primary counter and the system control logic, enabling the primary counter to maintain high precision while the system overall maintains reliability through the secondary counter's oversight.
2Measurement precision
If the counter rate is increased to improve measurement precision, then measurement precision improves, but device complexity increases due to need for multiple counters
Solution Approach 1:
The patent segments the counter system into two distinct components with different functions: a primary high-rate counter for precision measurement and a secondary low-rate counter for range monitoring. This segmentation enables each component to be simple and focused, reducing overall system complexity while achieving high precision.
Solution Approach 2:
Both counters serve multiple purposes: the primary counter provides precise measurements for normal operation, while also serving as the basis for RMS calculations and phase-locked loop synchronization. The secondary counter provides range monitoring and can trigger adjustments to the primary counter's operating parameters, making the system adaptable without requiring complete redesign.
3Productivity
If the counter rate is set high to maximize useful bandwidth, then productivity improves, but loss of information increases due to potential aliasing
Solution Approach 1:
The secondary counter performs preliminary detection of out-of-range periods before the primary counter would potentially alias. By monitoring for abnormal period lengths in advance, the system can prevent aliasing errors from occurring in the primary counter's measurements, thus preserving information integrity while maintaining high productivity.
Solution Approach 2:
The system implements feedback through the secondary counter's monitoring of period ranges. When the secondary counter detects out-of-range conditions, it provides feedback that triggers system response (such as adjusting the primary counter's clock rate or flagging the measurement), preventing aliasing and information loss while allowing the primary counter to operate at high speed for normal conditions.
Data Source
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AI summary
Aspects are directed to systems and methods of determining a value of a characteristic related to timing between sequential events of an input electronic signal using an input capture counter having a maximum counting value, the input electronic signal having an expected variable period between events whose value is between a maximum period value and a minimum period value with a delta period value equal to a difference between the maximum period value and the minimum period value.