Cooperative GPS Multipath Rejection via Intermediary Signal Filtering

Solution Overview

Problem

Satellite-based position determination systems, such as GPS, face accuracy issues due to interference from multipath signals, particularly in urban environments where reflections from buildings and structures degrade the direct path range estimate, leading to poor tracking accuracy and potential misdirection of GPS navigation.

Innovation Solution

The system improves location determination by using a reference-receiver to receive distance information from unknown-location receivers and beacon-distance information from beacons, filtering correlation coefficients to compute the likely locations of unknown-location receivers, and applying geometric constraints to reject incorrect position estimates caused by multipath signals, thereby enhancing accuracy in high-noise environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If GPS receivers use direct path range estimates from satellite signals, then positioning can be achieved, but accuracy deteriorates in urban environments due to multipath signals from buildings and structures

Engineering Contradiction:

Improvepositioning accuracyVSAvoidmultipath interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary processing system that receives signals from multiple satellites and multiple receivers, then uses statistical signal processing to separate direct path signals from multipath reflections. This intermediary analysis layer filters out harmful reflected signals before position calculation, resolving the contradiction between achieving positioning and maintaining accuracy in multipath environments.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent combines signals from multiple satellites and multiple receivers to create a system where the direct path signal emerges as the dominant consistent component through statistical analysis. By merging multiple signal sources and using correlation techniques, the system identifies and extracts the true direct path signal while rejecting multipath reflections, thereby maintaining positioning accuracy in urban environments.

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If multiple satellites are used to determine receiver position, then positioning accuracy improves, but the system becomes more vulnerable to multipath interference from surrounding structures

Engineering Contradiction:

Improvepositioning accuracyVSAvoidsignal reflections from buildings

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary processing system that receives signals from multiple satellites and multiple receivers, then uses statistical signal processing to separate direct path signals from multipath reflections. This intermediary analysis layer filters out harmful reflected signals before position calculation, resolving the contradiction between achieving positioning and maintaining accuracy in multipath environments.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses feedback from multiple receiver measurements and satellite signal correlations to continuously refine the separation between direct and reflected signals. By analyzing the consistency of signal characteristics across multiple measurements and using this feedback to adjust signal processing parameters, the system maintains accuracy even as multipath conditions vary in urban environments.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If GPS navigation is used in urban areas with building reflections, then navigation can be provided, but tracking accuracy becomes poor causing misdirection

Engineering Contradiction:

Improvenavigation functionalityVSAvoidtracking accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary processing system that receives signals from multiple satellites and multiple receivers, then uses statistical signal processing to separate direct path signals from multipath reflections. This intermediary analysis layer filters out harmful reflected signals before position calculation, resolving the contradiction between achieving positioning and maintaining accuracy in multipath environments.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful multipath reflections into beneficial information by using the statistical properties of reflected signals across multiple receivers and satellites. The system identifies patterns in multipath interference and uses these patterns to refine signal separation, effectively turning the presence of building reflections from a source of error into a means of verifying and improving position accuracy.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS10330790B2Multipath rejection using cooperative GPS receivers

Publication Date: 2019.06.25 KBR WYLE SERVICES LLC

AI summary

Systems and methods are disclosed for improving the speed and accuracy of terrestrial tracking with more than one receiver. Furthermore, terrestrial tracking of more than one receiver can be improved in areas where terrestrial tracking has been difficult to accomplish with acceptable accuracy, such as in rural areas where buildings can reflect satellite, and other, signals. For example, fast and precise position estimation in a short delay multipath environment can be solved by simultaneously estimating the position of multiple receivers using receiver to receiver distance ranges.