Modulated Beacon Light Source DC Bias for Indoor Positioning
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Solution Overview
Problem
Existing indoor positioning systems face challenges in accuracy due to the limitations of GPS in indoor environments and the unpredictability of radio wave propagation in complex indoor settings, necessitating a more reliable and accurate method for locating mobile devices within buildings.
Innovation Solution
A light-based positioning system utilizing modulated beacon light sources, where LEDs transmit identification information through visible light, allowing mobile devices to determine their position by capturing and demodulating the light signals, leveraging photogrammetric techniques for precise location calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light source is modulated to transmit positioning data, then positioning accuracy is improved, but thermal heating of the light source increases causing drooping effect
Solution Approach 1:
The light source is modulated using periodic action where the modulation signal alternates between high and low states. By carefully designing the duty cycle and frequency of this periodic modulation, the system achieves accurate positioning data transmission while controlling the average power output to minimize thermal heating and drooping effects.
Solution Approach 2:
The system dynamically adjusts modulation parameters including frequency, amplitude, and duty cycle to optimize positioning accuracy while maintaining thermal conditions within acceptable ranges. By changing these parameters adaptively, the system resolves the contradiction between achieving high measurement precision and controlling temperature rise.
2Reliability
If the peak output level of modulation is increased to improve signal strength, then positioning reliability is improved, but thermal heating increases causing drooping effect
Solution Approach 1:
The modulation scheme uses periodic action with optimized duty cycle where the light source operates at high peak output levels during active modulation periods but rests during inactive periods. This periodic on-off pattern allows achieving reliable positioning signals while controlling average power and thermal heating through appropriate duty cycle selection.
Solution Approach 2:
The system employs dynamic modulation where the peak output level, frequency, and duty cycle are adjusted in real-time based on positioning requirements and thermal conditions. This dynamic adaptation allows maintaining high reliability when needed while preventing excessive thermal heating through reduced power periods.
3Measurement precision
If modulation frequency is increased to improve positioning precision, then measurement accuracy is improved, but energy consumption increases
Solution Approach 1:
The system optimizes modulation frequency as a variable parameter, selecting the minimum frequency required to achieve the desired positioning precision. By dynamically adjusting the frequency parameter based on actual positioning requirements rather than using fixed high frequencies, the system achieves high measurement precision while minimizing unnecessary energy consumption.
Solution Approach 2:
The modulation scheme uses partial action where the light source is modulated only during necessary periods rather than continuously. By applying modulation intermittently at optimized frequencies rather than continuous high-frequency modulation, the system achieves sufficient positioning precision while significantly reducing overall energy consumption.
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
The system provides accurate indoor positioning with high precision, enabling reliable location-aware services and content delivery by using highly directional optical signals, overcoming the limitations of traditional GPS and radio-based methods.
Implementation Method 1
LEDs transmit identification information through visible light
Implementation Method 2
mobile devices to determine their position by capturing and demodulating the light signals
Data Source
AI summary
In one aspect, the present disclosure relates to a method for modulating a beacon light source in a light based positioning system. In some embodiments, the method includes selecting a modulation scheme for the light source, the modulation scheme periodically varying an output of the light source from a peak output level to a bottom output level, applying the modulation scheme to the light source, and adding a DC bias to the modulation scheme, the DC bias reducing the peak output level and increasing the bottom output level of the modulation scheme. In some embodiments, the peak output level is increased beyond an un-modulated output of the light source and an average output of the light source is substantially equal to the un-modulated output of the light source. In some embodiments, the peak output level includes an un-modulated output of the light source.