Part of that warning_results structure are 3 data values. For normal WARN products,
these contain the average and maximum data values within the detected centroid. When
generated with the target detection algorithm, these contain:
• The average and maximum height of the target returns (km).
• The average and maximum pile height.
• The average and maximum elevation angle of the target returns in degrees.
5.3.5 Target Detection: Input Task and Product Optimization
The airborne target detection, tracking and warning features of the DWELL algorithm are
designed to detect aircraft or flocks of migrating birds and issue automatic warnings.
Aircraft and migratory bird flocks tend to move with a fairly constant speed and direction
and this property is used to distinguish between airborne targets and other targets. In many
cases, targets embedded in weak weather targets or clear air echoes can be distinguished.
As with any automatic detection algorithm, there is a direct tradeo between the probability
of detection and the false alarm rate. For best performance, you must optimize the scan task
and the input product generation.
Scan Task Optimization
Target detection requires that extraneous targets such as clutter, second trip echo and noise
be eliminated. The update rate should be fairly rapid to resolve the target motion and
provide more continuous information on the target locations. Some knowledge of the likely
altitudes of flight is required to construct the volume scan task.
Table 15 Optimizing Scan Task for
DWELL Target Detection
Parameter Description
Maximum range 60 ... 100 km (37.3 ... 62.1 mi).
The maximum range of detection depends on the performance
characteristics of the radar.
Typically about 60 km (37.3 mi) detection range can be expected for a 1
to 1.5° beam width antenna.
Maximum resolution permitted by
the signal processor
For example, 125 meters (410 ft 1 in).
This depends on the processor performance characteristics.
Maximum PRF and minimum pulse
width
--
2nd trip echo cancellation On magnetron systems, SQI thresholding of the dBZ may be used
instead of this.
This discards non-coherent targets such as 2nd trip echoes.
Ground clutter filtering with an
aggressive CSR threshold (lower
value). alarms.
The value depends on the radar phase stability performance
characteristics but is typically be in the range 10 ... 20 dB.
The goal is to eliminate strong clutter targets which could produce false
alarms.
SQI Adjusted higher than usual. For example, approximately 0.45
This is to eliminate velocity speckles which could produce false alarms.
Chapter 5 – Configuring and Scheduling Optional IRIS Products
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