Chirp Modulated Ranging System for Indoor Positioning
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Solution Overview
Problem
Existing wireless transmission systems face challenges in achieving long transmission ranges with low power consumption and simple receivers, while also ensuring accurate position information and security, as they often require high complexity, high power consumption, and are not suitable for indoor environments.
Innovation Solution
A wireless transmission scheme using chirp spread spectrum with a radio modem that employs base and modulated chirps, allowing for precise range estimation between devices over long distances with low energy consumption, featuring a transceiver architecture that includes a baseband and radiofrequency section, and utilizes chirp modulation with cyclic shifts and conjugate chirps for synchronization and security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS or satellite-based localization systems are used, then ranging precision over long ranges is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces complex satellite-based electromagnetic positioning systems with a simpler radio-based chirp signal exchange system. The mechanical/electromagnetic complexity of GPS receivers is substituted with a simpler radio transceiver that uses chirp modulation and FFT correlation, achieving comparable ranging precision through a different physical approach that is less complex and more suitable for indoor environments.
Solution Approach 2:
The patent uses a simplified model of signal exchange between two radio devices, copying the essential ranging function from complex satellite systems. Instead of receiving signals from multiple satellites and performing complex trilateration, the system copies the core principle of time-of-flight measurement using a simple two-way chirp signal exchange, achieving accurate ranging with much lower complexity.
2Measurement precision
If UWB ranging systems are used, then ranging precision is improved, but transmission range is limited
Solution Approach 1:
The patent changes key parameters of the radio signal, specifically using chirp modulation with cyclic shifts instead of traditional UWB impulsive signals. By adjusting the chirp duration, bandwidth, and using frequency hopping, the system achieves both long transmission range and accurate ranging precision, resolving the contradiction between UWB's precision and range limitations.
3Device complexity
If WiFi positioning is used, then system complexity is reduced, but position information accuracy deteriorates
Solution Approach 1:
The patent employs periodic chirp signal exchanges with structured timing, where devices alternately transmit and receive chirp signals in a synchronized manner. This periodic action enables accurate time-of-flight measurement while keeping the system simple, achieving both low complexity and high positioning accuracy by using regular, predictable signal patterns rather than continuous WiFi scanning.
4Speed
If fast impulsive chirps with large bandwidth are used, then ranging speed is improved, but transmission range is limited
Solution Approach 1:
The patent makes the chirp signal parameters dynamic, adjusting chirp duration, bandwidth, and frequency hopping patterns based on transmission conditions. This dynamic adaptation allows the system to achieve fast ranging when conditions permit while extending transmission range when needed, resolving the contradiction between speed and range by making the system flexible rather than fixed.
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 solution enables accurate range estimation over long distances with reduced complexity and power consumption, while ensuring secure and precise positioning, and is robust to errors, allowing operation in obstructed environments and indoor settings.
Implementation Method 1
a radio modem 310, 510 capable of communicating with at least one other device 521-524 by radio signals
Implementation Method 2
chirp spread spectrum with a radio modem that employs base and modulated chirps, allowing for precise range estimation between devices over long distances
Data Source
AI summary
A ranging and positioning system comprising transmitters and receiver nodes communicating together by chirp-modulated radio signals, that have a ranging mode in which ranging exchange of signals takes place between a master device and a slave device that leads to the evaluation of the range between them. The slave is arranged for recognizing a ranging request and transmit back a ranging response containing chirps that precisely aligned in time and frequency with the chirps in the ranging requests, whereupon the master can receive the ranging response, analyze the time and frequency the chirps contained therein with respect to his own time reference, and estimate a range to the slave.