GNSS Multipath Mitigation Using Image Sensor Obstruction Detection
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Solution Overview
Problem
GNSS devices face significant accuracy issues due to multipath errors caused by signal reflections from nearby surfaces, which distort pseudo-range and carrier phase measurements, making it challenging to achieve high precision positioning, especially in handheld devices.
Innovation Solution
A handheld GNSS device that incorporates an image sensor and orientation sensors to determine obstruction regions, allowing it to exclude or de-weight signals from satellites within these regions, thereby mitigating multipath errors by using image data and orientation information to accurately position the device based on clear satellite signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If GNSS device uses signals from all visible satellites for positioning, then the number of available satellites increases, but positioning accuracy deteriorates due to multipath errors from reflected signals
Solution Approach 1:
The patent segments the satellite signals into two categories: direct signals and reflected signals. By using the image sensor to identify obstruction regions, the system separates satellites whose signals are likely to be reflected (those positioned near or within obstruction regions) from those providing direct signals. This segmentation allows the device to selectively process only the reliable direct signals for positioning calculations.
Solution Approach 2:
The patent performs preliminary identification of obstruction regions using the image sensor before processing GNSS signals. By capturing images and determining obstruction regions in advance, the system pre-identifies which satellites are likely to provide reflected signals. This preliminary action allows the device to exclude problematic satellites before positioning calculations begin, preventing multipath errors from degrading accuracy.
2Measurement precision
If GNSS device excludes signals from satellites in obstruction regions, then positioning accuracy improves by reducing multipath errors, but the number of available satellites decreases
Solution Approach 1:
The patent changes the selection parameter for satellite signals from purely geometric visibility to a combined criterion that includes obstruction region proximity. By introducing the obstruction region parameter into the satellite selection process, the system can identify and exclude satellites whose signals are likely to be reflected, even if they are geometrically visible. This parameter change enables more accurate filtering of multipath-affected signals.
3Measurement precision
If GNSS device uses image sensor and orientation sensors to identify obstruction regions, then positioning accuracy improves through multipath mitigation, but device complexity increases
Solution Approach 1:
The patent makes the image sensor serve multiple functions: it captures images for obstruction region identification and also provides data for determining satellite positions relative to obstructions. By using the same sensor for both imaging and multipath mitigation purposes, the system avoids adding separate dedicated components, thereby reducing overall device complexity while still achieving improved positioning accuracy.
Data Source
AI summary
A method for mitigating the effects of multipath errors in GNSS devices is provided. Signals from GNSS satellites are received. Image data from an image sensor is received. Orientation data from an orientation sensor is received. The orientation data describes the orientation of the image sensor. Obstruction data is determined based on the image data. The obstruction data includes an obstruction region that indicates the sky in that region is obstructed by a structure. Based on the orientation data, obstruction data, and GNSS satellite location data, the position of GNSS satellites with respect to the obstruction region is determined. The location of the GNSS device is determined based on signals from some of the GNSS satellites and the position of GNSS satellites with respect to the obstruction region.