GNSS Carrier Phase Correction for CRPA Anti-jamming
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Solution Overview
Problem
Active null and beam steering in controlled radiation pattern antennas (CRPAs) for GNSS positioning systems introduces phase center movements, which affect carrier phase measurements and prevent effective use of short baseline RTK information, leading to inaccurate position determination and inability to resolve carrier cycle ambiguities.
Innovation Solution
A carrier phase correction subsystem that calculates and applies phase corrections to CRPA filtered signals based on assigned weights, azimuth and elevation angles, and radiation pattern values, ensuring that carrier phase measurements have a common endpoint at the antenna phase center, allowing for precise position determination and utilization of RTK information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active null and beam steering is applied in CRPA to cancel jamming signals, then anti-jamming capability is improved, but phase center movements are introduced that degrade carrier phase measurement accuracy
Solution Approach 1:
The patent introduces an intermediary phase correction mechanism that mediates between the CRPA's null steering function and the carrier phase measurement requirement. The correction subsystem calculates phase corrections based on the weighted combination of antenna element signals and applies these corrections to compensate for phase center movements, allowing both anti-jamming and precise positioning to coexist
Solution Approach 2:
The patent changes the parameter space by introducing phase correction values that adjust the carrier phase measurements. By calculating phase corrections from the CRPA weightings and antenna element positions, and applying these corrections to the measured phases, the system transforms the degraded measurements into accurate positioning data while maintaining the null steering functionality
2Object-affected harmful factors
If CRPA weighting is applied to produce nulls for jamming cancellation, then jamming signal rejection is improved, but the ability to resolve carrier cycle ambiguities using RTK information is lost
Solution Approach 1:
The phase correction subsystem acts as an intermediary that restores the relationship between carrier phases from different antenna elements after CRPA weighting. By calculating and applying phase corrections based on the weightings and antenna geometry, the system enables RTK processing to resolve carrier cycle ambiguities even when null steering is active
Solution Approach 2:
The patent applies preliminary anti-action by pre-calculating phase corrections from the CRPA weightings and antenna element positions before carrier phase measurements are taken. These corrections are then applied to the measurements, preventing the phase center movements from interfering with RTK ambiguity resolution
3Reliability
If multiple antenna elements are weighted and combined for null steering, then anti-jamming performance is improved, but position determination accuracy degrades due to phase center movements
Solution Approach 1:
The phase correction subsystem serves as an intermediary that bridges the gap between CRPA signal combination and accurate position determination. It calculates phase corrections from the weighted antenna element signals and applies these corrections to the carrier phase measurements, ensuring that position accuracy is maintained despite the phase center movements caused by null steering
Solution Approach 2:
The system implements feedback by using the CRPA weighting information and antenna element positions to calculate phase corrections, which are then applied to the carrier phase measurements. This closed-loop approach ensures that the position determination accuracy is maintained by continuously compensating for phase center movements based on the actual weighting applied
Data Source
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Figure 3A~3B
AI summary
A carrier phase correction sub-system for use with a GNSS receiver that utilizes an active null and beam steering controlled radiation pattern antenna (CRPA) determines carrier phase corrections that compensate for antenna phase center movements in the carrier phase measurements taken from the CRPA filtered signal. The carrier phase sub¬ system utilizes measured radiation patterns, angles of incidence of the satellite signals at the CRPA, and the applied weights to determine carrier phase corrections to be applied to the CRPA filtered signals from which the carrier phase measurements are later taken or to the carrier phase measurements depending on the dynamics of the jamming signal. With the carrier phase corrected, the GNSS receiver may utilize known RTK techniques to resolve carrier cycle ambiguities.