Multi-Frequency Phase Comparison for GNSS Positioning
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Solution Overview
Problem
Current Global Navigation Satellite Systems (GNSS) face challenges in accuracy and availability, particularly in dense urban environments and indoors, where traditional positioning methods fail due to unreliable satellite signal reception.
Innovation Solution
A method utilizing a single transmitter that broadcasts signals at two different frequencies, allowing two separate receivers to determine position and/or time by comparing the phases of these signals, which can increase coverage and precision by using phase relationships across a wider frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional GNSS trilateration using single-frequency satellite signals is used, then the system is simple to implement, but positioning accuracy and availability deteriorate in dense urban environments and indoors
Solution Approach 1:
The patent applies parameter changes by utilizing multi-frequency signals instead of single-frequency signals. The receiver measures carrier phases at multiple frequencies (e.g., L1, L2, L5 bands) and uses the phase differences between frequencies to calculate position. This changes the fundamental parameter of signal frequency from single to multiple, enabling improved accuracy through phase comparison while maintaining system feasibility
Solution Approach 2:
The patent introduces an additional dimension by comparing phases across different frequency dimensions. Instead of relying solely on time of arrival measurements, the system measures carrier phases at multiple frequencies and computes phase differences, adding a frequency-differential dimension to the positioning calculation that enhances accuracy particularly in challenging environments
2Reliability
If traditional single-frequency GNSS signals are used, then the system has low complexity, but availability deteriorates in environments with unreliable satellite signal reception
Solution Approach 1:
The patent changes the signal parameter from single-frequency to multi-frequency by receiving and processing carrier phases at multiple frequency bands simultaneously. This allows the system to maintain reliability when one frequency is blocked or degraded by using phase measurements from other frequencies, thereby improving availability in urban canyons and indoor environments
Solution Approach 2:
The patent uses the carrier phase as an intermediary measurement that can be derived from multiple frequency signals. By measuring the phase of carrier waves at different frequencies and comparing them, the system creates an intermediate measurement product that is more robust to signal blockage than traditional time of arrival measurements alone
3Measurement precision
If multi-frequency phase comparison is implemented, then positioning accuracy improves, but the complexity of phase measurement and comparison increases
Solution Approach 1:
The patent segments the positioning problem into separate frequency components by measuring carrier phases independently at each frequency band (L1, L2, L5) and then combining these segmented measurements through phase comparison. This segmentation approach simplifies the measurement process by handling each frequency separately before integration, making the complex multi-frequency measurement manageable
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 approach enhances positioning accuracy and availability by generating additional measurements from pairs of signals at different frequencies, improving precision and coverage, even in environments where traditional GNSS systems are unreliable.
Implementation Method 1
a first phase of a first wireless signal transmitted by a transmitter at a first frequency and received by a first receiver
Implementation Method 2
characterizing a first phase of a first wireless signal transmitted by a transmitter at a first frequency
Data Source
AI summary
Methods and apparatus for assisting positioning or timing calculations. In one aspect the invention provides a method for assisting a determination of a position or a time, the method comprising: obtaining first phase information, the first phase information characterizing a first phase of a first wireless signal transmitted by a transmitter at a first frequency and received by a first receiver at a first location; and obtaining second phase information, the second phase information characterizing a second phase of a second wireless signal transmitted by the transmitter at a second, different frequency and received by a second receiver at a second, different location. The method further comprises comparing the first phase information with the second phase information to produce phase comparison information; and using the phase comparison information to assist in the determination of a position or a time.