Listening and Surveillance Devices Act 1972
surveillance device means a visual surveillance device or a tracking device; (ii) used a surveillance device that was not installed through the exercise

US Surveillance Laws
(1) the acquisition by an electronic, mechanical, or other surveillance device of the contents of any wire or radio communication sent by or intended to be

Patent 4264978: Device for locating audio surveillance apparatus
is sensed by an audio surveillance device and retransmitted as modulated whereby the display indicates the distance to the surveillance device.

InformationWeek > Wireless Surveillance Device > Cops Play
The Eye Ball R1 wireless camera and microphone gives police a 360-degree view of a crime scene.