Real-Time Clock Compensation Using IIR Oscillator Temperature Estimation
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Solution Overview
Problem
Existing real-time clocks in electricity meters face inaccuracies in temperature compensation, leading to errors in timing due to indirect temperature measurements, which are not sufficient to meet stringent industry standards like ANSI C12.1-2001 requirements, especially under rapid ambient temperature changes.
Innovation Solution
A temperature compensated real-time clock system that uses an infinite impulse response filter to estimate the temperature of a crystal oscillator, considering thermal gradients and masses, and adjusts the clock's frequency based on this estimation to provide accurate compensation factors, incorporating a temperature sensor and digital logic within a system on a chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensor is used to measure temperature for compensation, then temperature compensation is provided, but the measurement precision deteriorates because the sensor does not directly measure the crystal oscillator temperature
Solution Approach 1:
The patent introduces an infinite impulse response filter as an intermediary computational model that indirectly estimates the crystal oscillator temperature by processing ambient temperature readings through a thermal response model. This mediator translates imperfect ambient temperature measurements into accurate crystal temperature estimates without requiring direct thermal contact.
Solution Approach 2:
The patent replaces the direct thermal coupling mechanism (physical thermal contact between sensor and crystal) with a computational substitution using digital signal processing. The infinite impulse response filter algorithm substitutes for the physical thermal path, calculating the crystal temperature based on the thermal response characteristics rather than direct measurement.
2Measurement precision
If a time delay is added to the temperature measurement to improve accuracy, then compensation accuracy improves slightly, but the solution deteriorates under rapid temperature shifts
Solution Approach 1:
The patent implements a dynamic infinite impulse response filter that continuously adapts to changing thermal conditions. Unlike a fixed time delay, the IIR filter dynamically processes temperature readings with varying weights based on the thermal response model, allowing it to accurately track crystal temperature during both slow and rapid temperature transitions.
Solution Approach 2:
The infinite impulse response filter incorporates feedback mechanisms where previous temperature estimates inform current calculations. This feedback loop allows the system to anticipate and accurately track rapid temperature changes by continuously refining the crystal temperature estimate based on the thermal model and new ambient temperature readings.
3Device complexity
If direct temperature measurement is used without compensation modeling, then device complexity is reduced, but manufacturing precision deteriorates due to inability to meet accuracy standards
Solution Approach 1:
The patent transforms the temperature compensation approach by changing the parameter processing method. Instead of using raw ambient temperature readings directly, the system applies parameter transformation through the infinite impulse response filter, converting ambient temperature data into accurate crystal temperature estimates that enable precise clock compensation.
Solution Approach 2:
The patent performs preliminary computational action by pre-establishing the thermal response model and infinite impulse response filter coefficients during manufacturing. This preliminary setup enables the system to automatically and accurately compensate for temperature effects during operation without requiring complex real-time adjustments or calibration procedures.
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 solution significantly enhances the accuracy of real-time clocks, meeting stringent accuracy standards and reducing compensation errors, even under rapid temperature shifts, thereby improving competitiveness and compliance with industry regulations.
Implementation Method 1
performing a transfer function for the temperature estimate as a function of the temperature and treating the oscillator as a first thermal mass on a first thermal gradient and treating the temperature sensor as a second thermal mass on a second thermal gradient
Implementation Method 2
The frequency of this crystal oscillator is a function of temperature
Data Source
AI summary
Systems and methods of a temperature compensated real-time clock are disclosed. The systems and methods can include measuring a temperature with a temperature sensor, detecting a temperature dependent frequency from an oscillator, inputting the temperature and determining a temperature estimate for the oscillator with an infinite impulse response filter, and determining a compensation factor, for the oscillator.