IEEE Aerospace and Electronic Systems Magazine - June 2020 - 10

The Development From Adaptive to Cognitive Radar Resource Management

Figure 2.
Example airborne scenario comprising various air targets with
differing trajectories.

searches a region using a static pattern comprising multiple
(typically sequential) beams and provides the resulting
measurements to a tracker. In terms of a transition from
mechanical beam steering to electronic beam steering, this
would be the simplest first step, which is simply to emulate mechanical beam steering behavior with electronic
beam steering.
The track accuracy and track completeness can be
seen in Figure 3(a) and (b), respectively. The performance
serves as a baseline for the following techniques.

ALERT-CONFIRM

Figure 1.
Cognitive radar architecture, including locations of the components
in typical subsystems. (a) Cognitive radar architecture indicating
locations of existing techniques. Each level constitutes a perception-action cycle. Generally data and information is processed
upwards and management is executed downwards. The times on the
right indicate the reaction time of each perception-action cycle.
(b) Location of the architecture components in typical subsystems.

the root-mean-squared error in the tracking results averaged over the multiple targets and multiple simulated
Monte Carlo runs. Track completeness is the fraction of
the targets that are under track, averaged over the simulated Monte Carlo runs.

TRACK-WHILE-SCAN
A radar system performing only track-while-scan does not
use adaptive radar resource management. Track-while-scan
10

The first step in incorporating adaptive radar resource
management is applying alert-confirm [11]. Alert-confirm
is an adaptive process that reacts by immediately scheduling a second dwell when a measurement generated in the
search cannot be associated to an existing track. The purpose of the second dwell is to determine whether a new
target is truly present or if the measurement is due to a
false alarm. The second dwell is scheduled immediately to
benefit from the temporally correlated radar cross section
that generated the original alert measurement. Alert-confirm enables a new track confirmation to be achieved on a
single search scan, without having to wait for consecutive
search scans. Consequently, the radar can acquire tracks
on targets quicker, resulting in an increased track acquisition range for inbound targets.
In Figure 3(b), the difference between track-while-scan
and alert-confirm can be seen for our example airborne scenario. It can be seen that the track completeness is significantly improved since tracks are confirmed earlier. The
drawback is that the additional dwells used for confirmations reduce the time available for other functions. However, this is generally a price worth paying when searching
in a noise limited environment. Correlated clutter returns
or jamming can reduce the effectiveness and, hence, the
applicability of alert-confirm.

IEEE A&E SYSTEMS MAGAZINE

JUNE 2020

IEEE Aerospace and Electronic Systems Magazine - June 2020

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