Crystal Frequency Compensation Using Multiple Temperature Sensors
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Solution Overview
Problem
Temperature variations in crystals used for generating oscillation frequencies in satellite navigation systems can inhibit the ability of devices to acquire and track GPS signals effectively.
Innovation Solution
A mobile device is equipped with multiple temperature sensors to measure the temperature of a crystal and a thermally coupled component, allowing the processor to estimate the crystal's temperature and compensate for changes in the reference frequency, thereby maintaining accurate signal acquisition and tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single temperature sensor is used to measure crystal temperature, then the device complexity is reduced, but the temperature measurement precision deteriorates due to inability to account for heat transfer from thermally coupled components
Solution Approach 1:
The temperature sensing function is segmented into multiple sensors: one sensor measures the crystal temperature directly, while another sensor measures the temperature of a thermally coupled component. This segmentation allows each sensor to capture specific thermal information, and the processor combines these measurements to compensate for heat transfer effects, thereby improving overall temperature measurement precision without requiring a single complex sensor.
Solution Approach 2:
The processor acts as an intermediary that receives temperature measurements from multiple sensors and computes a compensated crystal temperature value. By introducing this computational intermediary, the system can account for heat transfer between the crystal and thermally coupled components, improving measurement precision while keeping individual sensors relatively simple.
2Measurement precision
If multiple temperature sensors are deployed to improve temperature measurement accuracy, then the temperature measurement precision improves, but the device complexity increases
Solution Approach 1:
The system uses existing thermal relationships in the device to its advantage. The thermally coupled component naturally serves as an additional temperature measurement point, and its temperature measurement automatically provides information about heat transfer effects. This self-service approach improves measurement precision by utilizing the device's own thermal characteristics rather than requiring entirely separate measurement systems.
3Reliability
If temperature compensation is not applied, then the device complexity is reduced, but the reliability of GPS signal acquisition and tracking deteriorates due to crystal frequency variations
Solution Approach 1:
The system implements a feedback mechanism where temperature measurements from multiple sensors are continuously monitored, and the processor dynamically compensates for crystal frequency variations based on these measurements. This feedback loop ensures that the reference signal frequency remains accurate despite temperature changes, improving GPS signal acquisition and tracking reliability while maintaining a relatively simple compensation approach.
Solution Approach 2:
The system changes the operational parameters of the crystal oscillator by applying temperature compensation algorithms. Based on measurements from multiple temperature sensors, the processor calculates the actual crystal temperature and adjusts the reference signal frequency accordingly. This parameter adjustment compensates for temperature-induced frequency drift, improving reliability without requiring hardware changes to the crystal itself.
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 approach enables more accurate determination of crystal temperature and frequency, improving the device's ability to maintain a stable GPS signal by accounting for heat transfer between components, leading to enhanced location determination capabilities.
Implementation Method 1
a first temperature sensor disposed proximate to the crystal and configured to measure the first temperature
Implementation Method 2
a second temperature sensor disposed and configured to measure the second temperature
Implementation Method 3
heat transfer between the component and the crystal via the electrically and thermally conductive line
Data Source
AI summary
A method in a mobile communication device includes: measuring a first temperature associated with a crystal configured to provide a reference signal having a frequency; measuring a second temperature associated with a component that is coupled to the crystal by an electrically and thermally conductive line; and compensating, based upon the measuring of the first and second temperatures, for a change in the frequency of the reference signal of the crystal.