Sir, I think our passive sensors might not be working properly.

Passive infrared sensors react to changes in heat, such as the pattern created by a moving person.

"Passive sensors are operating at just seven percent efficiency," the unit answered.

We have to rely on passive sensors, which are notorious for their short range and lack of sensitivity.

Passive sensors sense the data without actually manipulating the environment by active probing.

Passive sensors can only analyze data that other entities and objects put out.

Passive acoustic sensors can detect aircraft flying low over the sea.

"Passive sensors are shown to make a valuable contribution to the air defence mission."

I want this all done with passive sensors.

Passive sensors and telescopics, combining their efforts by way of a computer, could offer a tentative picture.