Crystal Oscillator Temperature Sensing via Communication Timing
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Solution Overview
Problem
Current thermal detection methods in electronic circuits, such as lighting systems, often require complex and costly dedicated thermal sensors or probes, which can compromise circuit stability and reliability, especially when using crystal oscillators with high temperature dependency.
Innovation Solution
A temperature sensing device that uses a second controller with a higher clock speed to measure time intervals between communications with a remote device, allowing for temperature determination based on the frequency-temperature characteristics of the remote device's crystal oscillator without the need for additional sensors or hardware modifications, utilizing statistical analysis of multiple challenge and response signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated thermal sensors or probes are used for temperature detection, then temperature measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The crystal oscillator in the remote device performs dual functions: its primary function of generating clock signals and its secondary function of serving as a temperature sensor. By measuring the oscillator frequency drift caused by temperature changes, the system obtains temperature information without adding dedicated sensing components. This self-service approach eliminates the need for separate thermal sensors while maintaining measurement capability.
Solution Approach 2:
The patent makes the crystal oscillator universal by enabling it to perform both time-keeping and temperature sensing functions. The same hardware component (the crystal oscillator) is used for generating clock signals for normal operation and for detecting temperature through frequency measurements, thereby eliminating the need for separate dedicated components.
2Measurement precision
If crystal oscillators with high temperature dependency are used for temperature sensing, then temperature sensitivity is improved, but frequency stability deteriorates
Solution Approach 1:
The patent segments the system into a master device with high-stability oscillator and remote devices with temperature-sensitive oscillators. This segmentation allows each component to be optimized for its specific role: the master device provides stable timing reference while remote devices provide temperature sensing capability, resolving the contradiction between stability and sensitivity.
Solution Approach 2:
The master device acts as an intermediary that receives frequency measurements from remote devices and converts them into temperature readings using calibration data. This intermediary approach allows remote devices to use simple temperature-sensitive oscillators while the master device handles the complex temperature calculation, separating the sensing function from the processing function.
3Measurement precision
If accurate frequency measurement of crystal oscillators is performed, then temperature determination accuracy is improved, but measurement difficulty increases for low temperature dependency oscillators
Solution Approach 1:
The system uses periodic challenge-response communication between master and remote devices. The master device sends periodic challenge messages and measures the time until the remote device responds. This periodic measurement approach accumulates statistical data that improves temperature determination accuracy while using simple timing measurements that are easy to implement.
Solution Approach 2:
The master device sends challenge messages to remote devices and measures the response timing feedback. This feedback mechanism allows the master device to calculate temperature based on the time delay caused by the remote device's clock frequency, which is affected by temperature. The feedback loop enables accurate temperature determination through simple time measurements.
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 method enables accurate temperature measurement without compromising circuit stability, using existing communication interfaces and software, and can monitor thermal conditions in lighting systems without the need for additional thermal sensors or complex circuits, thus improving reliability and cost-effectiveness.
Implementation Method 1
a first crystal oscillator having a frequency-temperature characteristics
Data Source
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AI summary
The invention provides a temperature sensing system and method. A chain of repeated sequential communications is made between a temperature sensing device having a first controller which is clocked by a first crystal oscillator and a remote device having a second controller which is clocked by a second crystal oscillator. The environment of the remote device has a less stable temperature than the environment of the temperature sensing device. A time interval associated with the chain of repeated communications is measured and from this a clocking frequency and hence the temperature at the remote device can be derived, based on knowledge of the frequency-temperature characteristics of the second crystal oscillator.