Page 421 - Fundamentals of Radar Signal Processing

FIGURE 5.41 The concept of clutter mapping for detection of strong targets in
clutter.

Instead of using the zero-Doppler output of a pulse Doppler processor

(typically an FFT of the slow-time data), many clutter maps systems pass the I/Q
slow-time data through a separate “zero velocity filter” as shown in Fig. 5.42.
The zero velocity filter serves the opposite purpose of an MTI filter. It is a
lowpass design, the output of which consists only of ground clutter and crossing
target returns. The design of the zero-Doppler filter can be optimized for the
clutter environment at a specific radar site and can also be made adaptive to

clutter changes, for instance due to weather in the area.

FIGURE 5.42 Zero-Doppler filter used to isolate low-Doppler targets and
ground clutter.

5.6.2 The Moving Target Detector
The moving target detector (MTD) is a term applied to the Doppler processing
system used in many airport surveillance radars. The MTD combines most of
the techniques discussed previously and others to achieve good overall moving