The IED Model 540S Remote Sensor is a component of the IED Ambient Analysis System. It operates with the 500 series Announcement Control System, 9000 series Titan digital audio platform, and the 8000 series TIPS system. The function of the 540S is to detect the ambient sound level (desired signal level plus undesired background level) in the areas to be controlled, to convert this level and to send this information back to the 540 Ambient Analysis System.

The 540S consists of an omnidirectional condenser microphone, a preamplifier, and an analog conversion module. The analog conversion module converts the audio signal to a varying DC waveform for use by the system. The 540S-2 includes a 2-gang brushed aluminum mounting plate for easy installation.