Ranging System Time of Arrival Delay Cancellation
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Solution Overview
Problem
Conventional ranging systems face challenges in accurately measuring time of flight due to unpredictable processing delays in transponders, which affects the reliability and accuracy of distance determination in ranging and location applications.
Innovation Solution
A ranging system protocol that decouples processing time from signal propagation time by using a challenge signal and a ranging signal with a calculable time interval, allowing the transponder to process and store a response signal before sending it upon receipt of the ranging signal, ensuring accurate time of flight calculation and enhancing security against unauthorized access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the transponder processes the challenge signal in real-time before responding, then the system complexity is reduced, but the timing accuracy deteriorates due to unpredictable processing delays
Solution Approach 1:
The transponder pre-calculates and stores the response signal to the challenge signal before receiving the ranging signal. This preliminary action eliminates unpredictable processing delays during the actual ranging measurement, as the response is already prepared and can be transmitted immediately upon receiving the ranging signal, thereby improving timing accuracy without increasing system complexity
2Loss of time
If the transponder transmits the response signal immediately after processing the challenge signal, then the response time is reduced, but the reliability deteriorates due to timing uncertainties and vulnerability to hijacking attacks
Solution Approach 1:
The patent introduces an intermediary ranging signal from the interrogator that triggers the transmission of the pre-calculated response signal. This intermediary mechanism allows the system to maintain fast response times while ensuring reliability, as the ranging signal acts as a controlled trigger that synchronizes the response transmission with the time of flight measurement, eliminating timing uncertainties and preventing unauthorized hijacking attacks
3Device complexity
If the system uses a simple reflector for ranging, then the device complexity is minimized, but the functionality deteriorates due to lack of authentication and data communication capabilities
Solution Approach 1:
The patent segments the transponder functionality into distinct modules: a signal receiver for receiving the challenge signal, a signal processor for pre-calculating the response signal, a buffer for storing the response signal, and a signal transmitter for transmitting the response. This segmentation allows the transponder to provide authentication and data communication capabilities while maintaining clear functional separation, enabling enhanced functionality without excessive complexity
Data Source
AI summary
The invention relates to a ranging system for measuring the distance between an interrogator and a transponder. The transponder includes: a signal receiver for receiving a challenge signal from an interrogator; a signal processor for processing the challenge signal and generating a response signal in response to the challenge signal; a buffer for storing the response signal generated by the signal processor; and a signal transmitter for sending the response signal stored in the buffer when the signal processor receives a ranging signal from the interrogator, wherein a time interval between the challenge signal and the ranging signal is known to both transponder and the interrogator.