Just through perimeter sensors.

"I don't see any of the usual data routes- " "We've taken over the perimeter sensors and reconfigured them."

Stirling induding some views taken by the perimeter sensors as the hulk barreled in, so they could see the havoc caused by collision and too-rapid deceleration.

On Earth, Omnius's perimeter sensors detected the invading force.

The Tiburonian was installing a perimeter sensor into one of the native jopka trees, facing toward Baldakor.

I checked the perimeter sensors.

In addition to perimeter sensors, modern alarm systems have motion detectors that sense the presence of a person in the prohibited space.

As service returned, it became apparent that something had destroyed some seventy degrees of perimeter sensors below the ten-meter level.

And, oh yes, the perimeter sensors are shorted between 17 and 18.

"Activate all perimeter sensors."