Graphics Programs Reference
In-Depth Information
Multiple Target Tracking
Track-while-scan radar systems sample each target once per scan interval,
and use sophisticated smoothing and prediction filters to estimate the target
parameters between scans. To this end, the Kalman filter and the Alpha-Beta-
Gamma ( ) filter are commonly used. Once a particular target is detected,
the radar may transmit up to a few pulses to verify the target parameters, before
it establishes a track file for that target. Target position, velocity, and accelera-
tion comprise the major components of the data maintained by a track file.
αβγ
The principles of recursive tracking and prediction filters are presented in
this part. First, an overview of state representation for Linear Time Invariant
(LTI) systems is discussed. Then, second and third order one-dimensional
fixed gain polynomial filter trackers are developed. These filters are, respec-
tively, known as the and filters (also known as the g-h and g-h-k fil-
ters). Finally, the equations for an n -dimensional multi-state Kalman filter are
introduced and analyzed. As a matter of notation, small case letters, with an
underbar, are used.
αβ
αβγ
9.5. Track-While-Scan (TWS)
Modern radar systems are designed to perform multi-function operations,
such as detection, tracking, and discrimination. With the aid of sophisticated
computer systems, multi-function radars are capable of simultaneously track-
ing many targets. In this case, each target is sampled once (mainly range and
angular position) during a dwell interval (scan). Then, by using smoothing and
prediction techniques future samples can be estimated. Radar systems that can
perform multi-tasking and multi-target tracking are known as Track-While-
Scan (TWS) radars.
Once a TWS radar detects a new target it initiates a separate track file for
that detection; this ensures that sequential detections from that target are pro-
cessed together to estimate the targetÓs future parameters. Position, velocity,
and acceleration comprise the main components of the track file. Typically, at
least one other confirmation detection (verify detection) is required before the
track file is established.
Unlike single target tracking systems, TWS radars must decide whether each
detection (observation) belongs to a new target or belongs to a target that has
been detected in earlier scans. And in order to accomplish this task, TWS radar
systems utilize correlation and association algorithms. In the correlation pro-
cess each new detection is correlated with all previous detections in order to
avoid establishing redundant tracks. If a certain detection correlates with more
than one track, then a pre-determined set of association rules is exercised so
Search WWH ::




Custom Search