Real Time Clock Module With Atomic Clock Accuracy
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Solution Overview
Problem
Existing real-time clocks (RTC) in electronic devices suffer from low accuracy due to inexpensive crystal oscillators, leading to significant time drift over extended periods, making them unsuitable for applications requiring precise timekeeping without constant external updates.
Innovation Solution
Integration of a high-precision oscillator, such as an atomic clock, with a programmable logic device (CPLD) to maintain accurate time in low power standby mode and provide a pulse-per-second signal for reinitializing the timing system upon power restoration, ensuring subsecond accuracy without external references.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a low-cost crystal oscillator is used in the RTC, then the device cost is reduced, but the time accuracy deteriorates significantly over extended periods
Solution Approach 1:
The patent combines a low-cost crystal oscillator with a microprocessor and software-based timekeeping algorithms to achieve high accuracy. The microprocessor continuously monitors and adjusts the time based on multiple factors including oscillator drift compensation, achieving accuracy comparable to expensive atomic clocks while using inexpensive components.
Solution Approach 2:
The patent dynamically changes operating parameters of the crystal oscillator through voltage control and temperature compensation techniques. By adjusting the oscillator's operating conditions and using software algorithms to compensate for environmental variations, the system maintains high time accuracy without requiring expensive temperature-controlled oven designs.
2Measurement precision
If a high-precision oscillator or atomic clock is integrated into the RTC module, then the time accuracy is significantly improved, but the device complexity increases
Solution Approach 1:
The patent uses a microprocessor to simulate and replicate the functionality of expensive atomic clocks through software algorithms. Instead of physically integrating complex atomic clock mechanisms, the system uses digital processing and mathematical models to achieve similar timekeeping accuracy, dramatically reducing hardware complexity.
Solution Approach 2:
The microprocessor serves multiple functions: it acts as the central processing unit, the timekeeping engine, the temperature sensor, and the compensation algorithm executor. This multi-functionality eliminates the need for separate dedicated circuits for each function, reducing overall module complexity while maintaining high accuracy.
3Reliability
If the RTC is designed to maintain accurate time without external updates, then the operational autonomy is improved, but the initial time setting complexity increases
Solution Approach 1:
The RTC system automatically performs timekeeping, drift compensation, and accuracy maintenance without requiring external intervention. The microprocessor continuously monitors time accuracy and adjusts for oscillator drift autonomously, eliminating the need for manual time setting or external synchronization after initial setup.
Solution Approach 2:
The system performs preliminary time synchronization and calibration during initial setup, storing compensation parameters and configuration data in non-volatile memory. This preliminary action enables the RTC to operate autonomously for extended periods without external updates, as the compensation algorithms are pre-configured based on manufacturer testing and characterization.
Data Source
AI summary
A device implementing a real time clock integrated module for outputting data indicating a time-of-day. The real time clock integrated module includes: a high-precision oscillator or atomic clock having an accuracy of 50 ppb (parts per billion) or better; a timing circuit for generating time-of-day data according to a clock signal outputted from the oscillator or atomic clock; a power source allowing the timing circuit to maintain time when the device is powered off. The timing circuit includes a real time clock and a logic device storing a timestamp. The timing circuit is configured when the device is powered off to update the timestamp value based on the oscillator or atomic clock and to generate a time reference signal and to provide to the device the updated timestamp value and the time reference signal that the device can use as a time reference once the device is powered up again.