Digital Delay Measurement Using XOR Signal Correlation
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Solution Overview
Problem
Existing methods for determining the distance between wireless devices in wireless systems, such as radio ranging, face challenges in accuracy due to synchronization issues and require complex setups like GPS or multiple triangulation methods, which are costly and time-consuming, especially in environments with interference or for tracking high-value assets.
Innovation Solution
The use of an exclusive-OR (XOR) function to evaluate the overlap between a sent digital signal and a returned digital signal, allowing for the estimation of distance based on the time difference, which simplifies the determination of the time of flight and location of mobile devices in wireless networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS or multiple triangulation methods are used to determine distance between wireless devices, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential measurement function from complex GPS/multilateration systems by using only the time-of-flight information and simple signal correlation, eliminating the need for multiple satellites or complex triangulation infrastructure while maintaining distance measurement capability
Solution Approach 2:
The patent uses signal copying and autocorrelation techniques where the transmitted signal is correlated with the received signal to measure delay, creating a simplified measurement model that replicates the distance measurement function without requiring complex positioning infrastructure
2Measurement precision
If GPS or multiple triangulation methods are used to determine distance between wireless devices, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary signal processing by pre-generating the transmitted signal template and preparing correlation algorithms before actual distance measurement, allowing rapid comparison between transmitted and received signals to quickly determine time-of-flight
Solution Approach 2:
The patent uses signal copying and autocorrelation techniques where the transmitted signal is correlated with the received signal to measure delay, creating a simplified measurement model that replicates the distance measurement function without requiring complex positioning infrastructure
3Measurement precision
If complex synchronization methods are used in chirp signal systems, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs self-service synchronization where the receiver uses the received chirp signal itself as the reference for measuring time offset, eliminating the need for separate synchronization signals or complex coordination between transmitter and receiver clocks
Solution Approach 2:
The patent uses signal copying and autocorrelation techniques where the transmitted signal is correlated with the received signal to measure delay, creating a simplified measurement model that replicates the distance measurement function without requiring complex positioning infrastructure
Data Source
AI summary
Distance between two devices is determined by sending a digital signal from a first device to a second device, and receiving a repeated signal from the second device in the first device. The repeated signal includes the digital signal sent from the first device resent by the second device. A time difference between the sent digital signal and the received repeated signal is determined by providing both the sent digital signal and the received repeated signal to a logic gate, the output of the logic gate indicating whether the digital signal and the received repeated signal are at same or different states. The output of the logic gate is evaluated to determine an approximate distance between the first device and the second device.