Wireless Terminal Elevation Estimation Using Temperature and Pressure Compensation
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Solution Overview
Problem
Existing methods for estimating the elevation of a wireless terminal in tall buildings are inaccurate due to the 'stack effect,' which alters the relationship between atmospheric pressure and elevation, leading to potential life-threatening errors in locating the terminal during emergencies.
Innovation Solution
A system that receives measurements of barometric pressure and temperature at the wireless terminal, combines these with location-dependent traits of radio signals, and uses a stack-effect compensation model to generate an accurate estimate of elevation, accounting for the unique pressure and temperature conditions within tall structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If atmospheric pressure measurements are used to estimate elevation in tall buildings, then the method is simple and widely applicable, but the accuracy deteriorates due to the stack effect altering pressure-elevation relationships
Solution Approach 1:
The patent changes the parameters used for elevation estimation from relying solely on atmospheric pressure to combining atmospheric pressure with temperature measurements. This parameter change allows the system to account for stack effect variations by observing how temperature correlates with pressure deviations, thereby maintaining simplicity while improving accuracy in tall building environments
Solution Approach 2:
Temperature acts as an intermediary parameter that helps decode the relationship between pressure and elevation in the presence of stack effect. By measuring temperature alongside pressure, the system can infer the stack effect's influence and compensate for it, transforming the unreliable pressure-only measurement into an accurate elevation estimate
2Ease of operation
If standard atmospheric pressure models are applied in tall buildings, then the calculation is straightforward, but the results become unreliable due to altered pressure relationships
Solution Approach 1:
The patent performs preliminary measurements of both temperature and atmospheric pressure before conducting the elevation calculation. This preliminary action captures the environmental conditions that define the stack effect characteristics, allowing the subsequent calculation to adjust for these conditions and produce reliable results without complex real-time adjustments
3Device complexity
If only atmospheric pressure is measured for elevation estimation, then the device complexity is low, but the measurement accuracy is insufficient in tall structures
Solution Approach 1:
The patent merges temperature sensing and atmospheric pressure sensing into a unified elevation estimation system. By combining these two measurement types, the system maintains relatively low device complexity (using standard smartphone sensors) while achieving sufficient measurement accuracy through the complementary information that temperature provides about stack effect conditions
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 significantly improves the accuracy of elevation estimation for wireless terminals in tall buildings, reducing errors and ensuring timely and precise location determination during emergencies.
Implementation Method 1
atmospheric pressure, PA, decreases logarithmically with elevation, ZA, according to the formula: PA=P0×e−ZA/H
Implementation Method 2
generating an estimate of the elevation of the wireless terminal based on: (i) the estimate of the lateral location of the wireless terminal, and (ii) the measurement of barometric pressure at the wireless terminal
Data Source
AI summary
A method for estimating the elevation of an wireless terminal inside of a tall structure is described that compensates for differences in temperature and atmospheric pressure between the inside and outside of the structure.