Monitors radio air for DEAD audio. This is a NodeRed RaspberryPi flow.
Detection of unbalanced line level audio (a.k.a. headphone jack output at loud volume) which will send a single email when audio is dead and a single email when its active.
Uses: DEAD AIR monitor for a radio station.
See: http://github.com/ClockLoop/NodeRedDeadAir for schematic.
http://github.com/ClockLoop/NodeRedDeadAir/blob/master/NodeRedDeadAir.png
http://flows.nodered.org/flow/e057b16968fa936fd652
