Kathrein UFE 371/S - Manual (Page 15)

Operation
15
Pause and Zoom
You can use these keys to make the picture smaller, or to switch to
freeze image.
The Quality Key (Auxiliary function for antenna adjustment)
In addition to the display showing strength and quality of reception, the
receiver has also an auxiliary function with an acoustic signal for the
antenna alignment.
To use this function, change to the desired programme, and press the
Quality key.
As soon as the quality display is activated, the receiver transmits an
acoustic signal, the frequency and action replay is the same as of the
received-signal.