Multichannel Receiver Phase Measurement Multipath Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing navigation systems face challenges in maintaining high precision due to multipath effects, which cause random jumps in signal phase measurements, affecting accuracy, especially in local positioning systems.
Innovation Solution
The method involves transmitting navigation signals with diverse pseudo-random codes, carrier frequencies, and polarizations from base stations to a mobile station, using a multichannel correlation receiver to measure phase differences and apply nonlinear filtration to eliminate anomalous phase changes, ensuring accurate coordinate calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase measurements are used for high-precision positioning, then positioning accuracy is improved, but multipath effects cause random jumps in signal phase that deteriorate measurement accuracy
Solution Approach 1:
The patent divides the signal reception system into multiple independent channels, each receiving signals through different paths or with different characteristics. By segmenting the measurement process across multiple channels, the system can identify and exclude multipath-contaminated measurements while retaining accurate direct-path measurements, thus resolving the contradiction between using phase measurements for precision and avoiding multipath effects.
Solution Approach 2:
The patent introduces an intermediary processing stage that analyzes signal characteristics (such as signal strength, phase stability, and correlation properties) to distinguish between direct and multipath signals. This intermediary analysis allows the system to filter out harmful multipath effects while preserving accurate phase measurements from direct signals, maintaining both precision and accuracy.
2Reliability
If multiple radio channels with different parameters are used to transmit navigation signals, then multipath effect compensation is improved, but device complexity increases
Solution Approach 1:
The patent makes the radio channels multi-functional by using the same physical infrastructure (antennas, receivers) to perform multiple tasks: signal transmission, signal reception, multipath analysis, and position calculation. The channels serve both as communication pathways and as measurement probes for characterizing multipath effects, thereby improving compensation capability without proportionally increasing complexity.
Solution Approach 2:
The patent exploits parameter changes across different radio channels (such as varying carrier frequencies, polarization types, or time-varying characteristics) to distinguish between direct and multipath signals. By analyzing how signal parameters behave differently across channels under multipath conditions, the system achieves reliable compensation while using the same hardware for multiple measurement purposes.
Data Source
AI summary
Method of reducing multipath effects on phase measurements, including receiving radio signals with different pseudo-random codes transmitted by at least four base stations, each at particular frequency received by one channel; measuring delay difference and phase difference from different pairs of base stations; calculating a current position of the receiver based on the measured phase differences and delay differences, wherein the base stations differ in pseudo-random codes at same frequencies or differ in carrier frequency or polarization type if using the same pseudo-random codes, and wherein a number of channels in the receiver exceeds a number of channels needed for the calculating of the current position; detecting anomalous jumps in phase of one or more channels, based on first or second derivative of the phase, as being indicative of multipath signal reception; removing those channels from calculation of current position; and calculating current position based on remaining channels.