The RB-SD1IP Silence detection unit is an upgraded version of the RB-SD1. The unit is a 1U rack mount device used to monitor an unattended stereo studio feed and in the event of the signal going quiet after a given period the unit will switch through an alternative stereo audio signal. This signal could be a recorded message (e.g. Normal service will be resumed, etc), a feed from a flashcard player, audio from a conected USB flash drive or an alternative recorded program. Controls are provided to start external equipment and to provide remote status indication.