Antenna Channel Calibration Using Correlation-Based Timing Alignment
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Solution Overview
Problem
In high-speed modulation transmission systems, delay variations among channels degrade the accuracy of amplitude and phase estimation, and phase variations occur during calibration, necessitating a precise calibration method for timing, amplitude, and phase in antenna systems with multiple antenna elements.
Innovation Solution
An antenna system comprising a reference signal generator producing a high auto-correlation signal, a delay unit generating delayed signals with varying delays, a calibration network combining output signals, and an analyzer determining timing, amplitude, and phase variations, allowing each transmission unit to calibrate its output signals based on analysis results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed modulation is used to increase transmission capacity, then productivity is improved, but delay variation among channels occurs which degrades measurement precision
Solution Approach 1:
The patent performs timing calibration before amplitude and phase calibration. The timing calibration unit adjusts timing offsets of each channel based on correlation detection, establishing proper time alignment before the subsequent amplitude and phase calibration processes. This preliminary timing adjustment prevents delay variation from degrading the precision of later calibration steps, enabling high-speed modulation to maintain both high productivity and measurement precision.
2Measurement precision
If orthogonal codes are used for signal separation to improve measurement precision, then amplitude and phase estimation accuracy is improved, but timing alignment must be perfect which is difficult to maintain due to delay variation
Solution Approach 1:
The patent segments the calibration process into three distinct units: timing calibration, amplitude calibration, and phase calibration. The timing calibration unit first adjusts timing offsets using correlation detection, then the amplitude calibration unit adjusts amplitude ratios, and finally the phase calibration unit adjusts phase differences. This segmentation allows each unit to focus on one parameter, making the overall calibration more reliable and less sensitive to timing variations.
Solution Approach 2:
The patent employs feedback mechanisms in each calibration unit. The timing calibration unit uses correlation detection to measure timing offsets and feeds this information back for adjustment. Similarly, the amplitude and phase calibration units use feedback from their respective measurements to adjust their parameters. This feedback approach ensures that each calibration step maintains optimal performance despite variations in the system.
3Reliability
If calibration is performed to minimize amplitude and phase variations, then reliability is improved, but device complexity increases due to additional calibration networks and procedures
Solution Approach 1:
The patent uses a universal calibration approach where the same correlation-based timing calibration unit serves multiple purposes: it provides timing offset information for the timing calibration unit, and the correlated signals are also used by the amplitude and phase calibration units. This multi-functional use of the correlation detection mechanism reduces the need for separate dedicated components for each calibration function, thereby reducing overall device complexity while maintaining high reliability.
Data Source
AI summary
A reference signal generator generates a reference signal having high auto-correlation. A delay unit delays the reference signal to generate delayed reference signals and outputs the reference signal and the delayed reference signals to the transmission units, respectively. A calibration network combines the output signals of the transmission units. An analyzer analyzes a correlation between a demodulated signal and the reference signal to determine variations of timing, amplitude and a phase of the output signal of each transmission unit. Each transmission unit calibrates the timing, amplitude and phase of the output signal based on a corresponding determination result.