CRPA GNSS Pseudorange Correction via Frequency Domain Phase Shift
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Solution Overview
Problem
Global Navigation Satellite Systems (GNSS) using Controlled Reception Pattern Antennas (CRPA) face challenges in compensating for group delay errors, which affect the accuracy of pseudorange measurements, particularly due to the complexity of multiple antenna element outputs and dynamic beam steering, unlike single-element antennas where simple subtraction methods can correct directionally dependent errors.
Innovation Solution
A generalized frequency-domain pseudorange correction method that compensates for channel-dependent errors such as group delay and wave propagation differences by using a CRPA with a signal conditioner and processor to convert signals into frequency domain, apply group delay calibration corrections, and combine signals using beam forming techniques to obtain compensated frequency domain signals, which are then converted back to time domain for accurate pseudorange measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a CRPA with multiple antenna elements is used to improve jamming resistance and signal-to-noise ratio, then reliability is improved, but device complexity increases and group delay errors affect measurement precision
Solution Approach 1:
The patent divides the CRPA system into multiple antenna elements that can be independently processed. Each element's signal is separately corrected for group delay errors through frequency domain processing, allowing the complex multi-element system to be managed as independent manageable segments rather than a monolithic complex system
Solution Approach 2:
The patent transforms the signal processing from time domain to frequency domain, where group delay corrections can be applied as simple phase shifts. This parameter transformation simplifies the correction process and enables efficient handling of the complex multi-element CRPA system
2Ease of operation
If simple subtraction methods are used to correct directionally dependent errors, then ease of operation is improved, but manufacturing precision and measurement precision deteriorate due to inability to correct CRPA-specific errors
Solution Approach 1:
The patent replaces simple time-domain subtraction methods with frequency-domain phase correction. By transforming the correction mechanism from mechanical/time-based subtraction to frequency-based phase adjustment, the system achieves both operational simplicity and high measurement precision for CRPA systems
Solution Approach 2:
The patent changes the correction approach from time-domain amplitude subtraction to frequency-domain phase adjustment. This parameter transformation allows for precise correction of group delay errors while maintaining ease of implementation through standard signal processing techniques
3Measurement precision
If frequency domain correction is applied to compensate for group delay errors, then measurement precision is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent implements a universal frequency domain correction framework that handles multiple CRPA elements, different satellite signals, and various error sources through a single integrated processing approach. This multi-functional system reduces overall complexity by unifying correction operations rather than requiring separate processing for each error type
Solution Approach 2:
The patent applies group delay corrections as preliminary phase adjustments in the frequency domain before subsequent signal processing steps. By pre-correcting the signals, the system simplifies downstream processing and reduces the computational complexity of later stages
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively reduces pseudorange errors by eliminating group delays inherent in receiver hardware, achieving high precision GNSS accuracy comparable to single-element antenna systems, even in dynamic platforms like aircraft, by applying phase shifts in the frequency domain and using delay-locked loops for accurate tracking.
Implementation Method 1
The processor is configured to convert the time domain digital signals into a plurality of frequency domain digital signals
Implementation Method 2
This method effectively reduces pseudorange errors by eliminating group delays inherent in receiver hardware, achieving high precision GNSS accuracy comparable to single-element antenna systems, even in dynamic platforms like aircraft, by applying phase shifts in the frequency domain
Implementation Method 3
combine for each GNSS transmitter and frequency the compensated frequency domain digital signals by using a beam forming technique
Implementation Method 4
track code modulations of the time domain filtered signals and convert the time domain filtered signals into GNSS pseudorange measurements for the plurality of GNSS transmitters
Data Source
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AI summary
Global Navigation Satellite System (GNSS) pseudorange measurements must be compensated for receiver hardware and directionally dependent antenna errors to obtain desired accuracies for high precision GNSS positioning applications. The problem of pseudorange measurement errors resulting from directionally dependent group delays is not an issue in Fixed Reception Pattern Antenna (FRPA) GNSS sensors. However, for the complex case of a GNSS receiver employing a controlled reception pattern antenna (CRPA) and dynamic beam steering, the multiplicity of combinations of antenna element outputs makes compensation of directionally dependent antenna induced errors more difficult, as the simple subtraction that might be used for FRPA compensation does not work with a CRPA. Example embodiments provide for frequency domain correction of GNSS pseudorange measurements in CRPA receivers. The correction takes place in the signal processing of the satellite signals, after they have been converted to the frequency domain, but before they are formed into beams for the respective satellites.