Mark Feldstein & Associates SP4080 Wireless Indoor Outdoor Speakers - #SP4080 - Manual (Page 6)

Signal LED on the Transmitter would be cut off automatically if there is no/weak
operation input signal from audio source for 4 minutes. When the signal comes
back, the transmitter will work again automatically.
NOTE :
You should now be able to place the speakers freely from room to room without
disruption. If disruption should occur (signal breaks up), press the “AUTO SCAN”
button under the speakers to maximize best reception.
If you hear interference from other components, switch the channel control of
transmitter, and then move the speakers to other free location. You can re-adjust
the tuning control by moving it among channels of the transmitter, then pressing
“AUTO SCAN” button of the speakers for best reception.
When transmitting / receiving over long distances, the signal from the system will
become weaker.