At its' highest resolution, the RAS family of Radars produce a significant quantity of data. Navigation Mode is a simple way of distilling the whole of the radar’s field of view to a much smaller dataset, containing the range and bearing of the key objects within the view. The processing to distil the radar data down to these key points can be carried out inside the radar, which reduces the network bandwidth requirements. Alternatively, the source code for this functionality is available, which allows customers to implement this processing within their own specific environment.
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The information below describes how the “Navigation Mode” output from a radar is derived from the radar’s view of the environment surrounding it.
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A much more robust, but computationally more intensive feature extraction method is CFAR - a “common form of adaptive algorithm used in radar systems to detect target returns against a background of noise, clutter and interference” (ISBN 0-201-19038-9). There are various implementations of CFAR, and this approach to feature extraction is much more capable in high clutter environments, or radar scenes where a fixed thresholding approach across all ranges and azimuths is inappropriate. |
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The Navtech RAS family of radars support a CFAR “point cloud” output over an RDP connection - more details are available here. This function is available in radar firmware 3.1.0.325 and later |
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Examples
The following images demonstrate how reducing the value of “Threshold” for a given field of view from a RAS6 radar affects the distribution of data within the Navigation Mode output.
In the scenes below, the source raw radar data is shown on the left hand side and the resultant Navigation Mode output is shown on teh right hand side.
The radar is mounted around 1.5m above ground level, and has a view of a grassed area, a roadway and some roadside hedges.
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