Protection level
The protection level sets how much error protection a DAB+ service carries. More protection makes the signal more robust but uses more capacity.
The protection level is a setting in the DAB+ signal that decides how much error protection a programme gets. Higher protection means the signal survives poorer conditions, but it takes more capacity from the multiplex.
Broadcasters balance the two. SRF points out that for use in shelters DAB+ can switch to a more robust profile called EEP-1A. For ordinary programmes the broadcaster picks a level that suits the coverage area.
Listeners do not set this. It is chosen at the transmitter, and the radio adapts automatically.