Distance Measuring Apparatus RF Filter Phase Delay Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing distance measuring apparatuses using phase detection systems face inaccuracies due to phase delays in RF filters, particularly when influenced by interfering waves, which hinder precise distance measurement between key and automobile in keyless entry systems.
Innovation Solution
Incorporating a signal interruption section between the antenna and filter sections to prevent interfering waves from affecting calibration, allowing for accurate measurement of delay phases and subsequent removal of filter delays, thereby enhancing distance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase detection system is adopted for distance measurement, then wireless communication distance measurement is enabled, but measurement precision deteriorates due to phase delay in RF filter
Solution Approach 1:
The patent performs calibration measurement in advance to obtain the delay phase of the RF filter. By measuring the phase difference between transmission and reception signals when the antenna is connected to the filter, the system pre-determines the filter's delay characteristics and stores this calibration data for later use in actual distance measurements, thereby compensating for the phase delay error.
Solution Approach 2:
The system uses the calibration results to feed back and correct the distance measurement computation. The measured delay phase from calibration is used to adjust the phase detection results during actual operation, creating a closed-loop correction mechanism that improves measurement precision by compensating for the filter's phase delay.
2Measurement precision
If calibration is performed with antenna connected to filter section, then delay phase measurement is enabled, but measurement precision deteriorates due to interfering waves
Solution Approach 1:
The patent performs calibration measurement in advance under controlled conditions (before actual distance measurement) to obtain the delay phase characteristics of the RF filter. By completing the calibration beforehand, the system captures the filter's phase delay in a stable environment, and this pre-obtained calibration data is then used to correct subsequent measurements, separating the calibration process from the actual measurement to avoid interference.
3Difficulty of detecting and measuring
If RF filter is used for band limitation, then signal filtering is improved, but measurement precision deteriorates due to filter delay phase
Solution Approach 1:
The system performs calibration measurement in advance to characterize the RF filter's delay phase. By measuring the phase difference between transmission and reception signals through the filter during calibration, the system pre-determines the filter-induced phase delay and stores this information for compensation during actual distance measurements.
Solution Approach 2:
The calibration results provide feedback that is used to correct the distance measurement computation. The stored delay phase information from calibration is applied to adjust the phase detection results, creating a compensation mechanism that maintains the filter's signal filtering benefits while eliminating its negative impact on measurement accuracy.
Data Source
AI summary
A distance measuring apparatus according to an embodiment includes, a filter section configured to perform band limitation on a transmission signal and output the transmission signal, and to perform band limitation on a reception signal from an antenna section and output the reception signal, a distance measuring section configured to perform a distance measurement computation based on the transmission signal and the reception signal, and to obtain a delay of a signal passing through the filter section and perform calibration of the distance measurement computation, a signal interruption section configured to interrupt transmission of a signal between the filter section and the antenna section, and a control section configured to control the signal interruption section to interrupt the transmission of the signal during a period of the calibration.