SPx Server's target tracking capability is enhanced in version V1.82 to support tracking directly from radar video, rather than from extracted plots. When the new mode is enabled, tracks without an associated plot can be updated by direct reference to the radar video. This permits very weak echoes, barely observable in the radar video and not otherwise generating a plot, to be used for the update.
A weighted centroid is calculated to provide the basis of the measurement, with checks to confirm that the video is likely to be target-derived rather than background noise. The new mode can extend the tracking range for small, weak targets which would otherwise be lost when no plot is observed.
In a normal update (top), a plot is extracted and used as the basis of the measurement. For a very weak target (bottom), no plot is extracted but the video in the search gate can be centroided to provide a measurement.
A technical note describing this capability is available here
More information about SPx Server is available here