Sennheiser EK 300 IEM G2 Instructions For Use Manual page 49

"MUTE" display
The "MUTE" display appears on the display panel when the RF signal of the
received transmitter is too weak.
"PILOT" display
The "PILOT" display
evaluation is activated (see "Activating/deactivating the pilot tone
evaluation (receiver only)" on page 66).
RF signal indication
The green LED (RF) at the front of the receiver lights up when an RF signal
is being received.
However, the green LED (RF) does not light up when the audio output is
muted because
the RF signal of the received transmitter is too weak,
the transmitter is set to mono operation and the receiver's pilot tone
evaluation is activated.
Display backlighting
After pressing a button, the display remains backlit for approx. 15 seconds.
appears on the display panel when the pilot tone
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