Graphics Programs Reference
In-Depth Information
Surface and Volume Clutter
Chapter 6
6.1. Clutter Definition
Clutter is a term used to describe any object that may generate unwanted
radar returns that may interfere with normal radar operations. Parasitic returns
that enter the radar through the antennaÓs main lobe are called main lobe clut-
ter; otherwise they are called sidelobe clutter. Clutter can be classified into two
main categories: surface clutter and airborne or volume clutter. Surface clutter
includes trees, vegetation, ground terrain, man-made structures, and sea sur-
face (sea clutter). Volume clutter normally has a large extent (size) and
includes chaff, rain, birds, and insects. Surface clutter changes from one area
to another, while volume clutter may be more predictable.
Clutter echoes are random and have thermal noise-like characteristics
because the individual clutter components (scatterers) have random phases and
amplitudes. In many cases, the clutter signal level is much higher than the
receiver noise level. Thus, the radarÓs ability to detect targets embedded in
high clutter background depends on the Signal-to-Clutter Ratio (SCR) rather
than the SNR.
White noise normally introduces the same amount of noise power across all
radar range bins, while clutter power may vary within a single range bin. Since
clutter returns are target-like echoes, the only way a radar can distinguish tar-
get returns from clutter echoes is based on the target RCS , and the antici-
pated clutter RCS (via clutter map). Clutter RCS can be defined as the
equivalent radar cross section attributed to reflections from a clutter area,
σ
t
σ
c
A
c
.
The average clutter RCS is given by
σ
0
A
c
σ
c
=
(6.1)
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