Ultra-wideband Antenna Array Delay Calibration
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Solution Overview
Problem
Radar systems face challenges in accurately determining the location of objects due to time-varying internal delays in transmitters and receivers, which are influenced by ambient conditions such as temperature and supply voltage, especially in Ultra-wide-Band systems requiring high precision like 'Through the Wall Radar Systems'.
Innovation Solution
A method and system for calculating real-time internal delays of transmitters and receivers by using direct signals to determine changes in time of arrival, accounting for initial delays and ambient conditions, allowing for precise location determination of objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If internal delays are assumed constant for simplification, then device complexity is reduced, but measurement precision deteriorates due to time-varying delays caused by ambient conditions
Solution Approach 1:
The system performs preliminary calibration by transmitting test signals through all antenna elements and measuring reception times to calculate initial internal delays before actual operation. This preliminary action establishes a baseline that compensates for time-varying delays during subsequent measurements, resolving the contradiction by preparing delay compensation data in advance without adding complexity to real-time operation.
Solution Approach 2:
The system continuously monitors reception times of direct signals and compares them against expected values to detect changes in internal delays. This feedback mechanism triggers recalculation of delay values when variations are detected, allowing the system to maintain measurement precision by adapting to ambient condition changes without requiring complex continuous monitoring during normal operation.
2Measurement precision
If calibration signals are transmitted through all antenna elements to calculate internal delays, then measurement precision is improved, but loss of time increases due to the calibration process
Solution Approach 1:
The system transmits calibration signals through only a subset of antenna elements rather than all elements, calculating internal delays for the necessary channels with sufficient precision. This partial action approach achieves adequate measurement precision for location determination while significantly reducing the time required compared to calibrating every antenna element in the array.
Solution Approach 2:
The calibration process is performed once during system initialization or setup, establishing internal delay values that remain valid for extended periods. This preliminary calibration action eliminates the need for frequent recalibration, thereby minimizing time loss while maintaining measurement precision during normal operational use.
3Measurement precision
If direct signals are used to calculate time of arrival changes, then measurement precision is improved, but device complexity increases due to additional signal processing requirements
Solution Approach 1:
The system extracts and utilizes the direct signal component from the received signals to calculate time of arrival changes, separating this essential information from other signal components. By focusing only on the direct signal path between transmitter and receiver, the system achieves high measurement precision without requiring complex processing of reflected, scattered, or multipath signals.
Solution Approach 2:
The system uses the naturally occurring direct signals between antenna elements for calibration and measurement purposes, rather than requiring additional dedicated calibration signals or external reference sources. This self-service approach leverages existing operational signals to provide the necessary timing information, improving precision without adding device complexity.
Data Source
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AI summary
A method for determining changes in internal delays of RF units, the RF units including a plurality of receivers and transmitters. The method includes providing initial direct signals' time of arrivals of the RF units initial internal delays of the RF units. Following this, each transmitter transmitting a direct signal, and the real-time direct signal's time of arrivals of the RF units, are measured. Then, changes in internal delays of the RF units are calculated based on the real-time direct signals' time of arrivals and initial direct signals' time of arrivals. And finally, real-time internal delays of the RF units are calculated based on the changes in internal delays and the initial internal delays of the RF units.