You should also have a security system with motion detectors, just in case.

IT is one thing to build a motion detector for a home security system.

We've seen stores with motion detectors, and they have been able to get around them.

The other would be for the motion detector on the gate itself.

Which meant the motion detector passed, at least the safety test.

Active systems protect an area with some sort of motion detector.

"Have you got that motion detector in place, old man?"

After the war, he used that technology to create motion detectors for alarm systems.

It was just an alarm, some sort of motion detector.

He picked the motion detector off the counter and turned it over in his hand.