Active Sensors

“Active” sensors detect objects by
bouncing energy off them and analyz-
ing the returned signal. Radar (TL6),
imaging radar (TL7), and ladar (TL8)
emit electromagnetic radiation, while
sonar (TL6) uses sound.
Active sensors never suffer dark-
ness penalties. They can sense objects
out to their rated maximum range at
no range penalty; each doubling of
range beyond that gives -2 to skill. The
major limitation of all such sensors is
that specialized but inexpensive detec-
tors can detect the scanning pulse at
up to twice their range. Each technol-
ogy also has a number of specific capa-
bilities and drawbacks; for details, see
the Scanning Sense advantage (p. 81).
Before TL9, only vehicular or
mounted units are likely to provide an
actual picture of the surroundings. At
TL6-8, a portable active sensor (e.g., a
police radar gun) usually only gives
the range and speed of objects it
detects.