Distance Measurement Circuit Delay Compensation for Key Ranging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing distance measuring devices face challenges in accurately measuring the distance between a key and a vehicle due to difficulties in accurately obtaining and compensating for circuit delay times, particularly because previous methods fail to account for differences in delay times at transmission and reception, and do not accurately measure delays in filters and amplifiers.
Innovation Solution
The proposed distance measuring device includes a configuration with multiple switching circuits and impedance adjustments to measure delay times at different loops, allowing for accurate compensation of total transmission and reception delays, thereby enabling precise distance calculation between movable devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional distance measurement methods are used, then the measurement process is simple, but the distance measurement accuracy is insufficient due to unaccounted circuit delay times
Solution Approach 1:
The patent divides the delay time measurement into separate segments: transmission delay time (Ttx) and reception delay time (Trx) are measured independently through distinct circuit loops. The transmission loop measures Ttx by transmitting a signal from the transmission circuit through the filter and amplifier to the reception circuit, while the reception loop measures Trx by transmitting a signal directly to the reception circuit. This segmentation allows accurate compensation of total circuit delay (Ttx + Trx) for precise distance measurement.
Solution Approach 2:
The patent performs preliminary measurement of transmission and reception delay times before actual distance measurement. By pre-measuring Ttx and Trx through the switching circuits that can configure different signal loops, the system obtains accurate delay values that are stored and used for compensation during subsequent distance measurements, eliminating the need for real-time delay calculation.
2Measurement precision
If delay time compensation is implemented, then distance measurement accuracy improves, but the device complexity increases due to additional switching circuits and measurement loops
Solution Approach 1:
The switching circuits in the patent serve multiple functions: they configure the transmission loop for Ttx measurement, configure the reception loop for Trx measurement, and enable actual distance measurement mode. The same transmission circuit, reception circuit, filter, and amplifier are reused across different measurement modes, reducing the need for dedicated separate circuits for each function.
Solution Approach 2:
The system performs self-measurement of its own transmission and reception delay times using its existing hardware components. The transmission circuit transmits test signals that loop back through the reception circuit, and the reception circuit processes these signals to determine delay times, eliminating the need for external delay measurement equipment.
3Reliability
If accurate delay measurement is performed, then the reliability of distance measurement improves, but the measurement time increases due to multiple loop measurements
Solution Approach 1:
The patent implements continuous operation of the measurement system by quickly switching between different measurement loops using the switching circuits. The transmission loop measurement and reception loop measurement are performed in rapid succession, and the system can transition to actual distance measurement mode without significant interruption, maintaining continuous useful action.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A distance measuring device according to an embodiment includes a filter, a first switching circuit, an impedance adjustable circuit, a second switching circuit, a third switching circuit, and a fourth switching circuit. The filter restricts a signal for distance measurement transmitted from the transmission circuit and a signal for distance measurement received by an antenna within a desired frequency band. The impedance adjustable circuit is adjusted to have a higher impedance than an impedance of the antenna. The second switching circuit switches conduction and non-conduction between the impedance adjustable circuit and the transmission circuit. The third switching circuit switches conduction and non-conduction between the impedance adjustable circuit and the reception circuit. The fourth switching circuit switches conduction and non-conduction between the impedance adjustable circuit and the second switching circuit and between the impedance adjustable circuit and the third switching circuit.