Rf Level; Noise Level; Headphone Level - Garmin Apollo SL40 User Manual

The RF Level function shows the relative signal strength

RF Level

of the frequency you are listening to. The range
displayed is between 0 and 255. The value will
constantly change as you are viewing it as signal
conditions change.
The Noise Level function shows the relative received

Noise Level

noise level of the frequency you are listening to. The
range displayed is between 0 and 255. The value will
constantly change as you are viewing it as signal
conditions change.
The Headphone Level function allows you to adjust the
Headphone
headphone audio level. Turn the Small knob to change
Level
the value. Setting the value to 0 slaves the headphone
audio level to the volume control knob. The range is
from 0 to 255.
RFLVL
NOISE
Hdphon Lvl
123
017
System Functions
11