Deepace KC908 Manual page 88

(8) Observe the position of the curve on the screen, if its upper part
exceeds the top of the screen, simply increase REF. If the curve is miles away
from the top of the screen, or its bottom part exceeds the screen bottom, the
REF should be decreased. If the gain is set to be relevant to the reference, the
lower the reference level, the higher the receiving sensitivity, and the weaker
the anti-interference ability.
Reference level and other settings that are relevant to signal intensity are
all in LEVEL menu. To modify these settings, press LEV button, input digits,
and select unit on the soft menu and press ENTER to confirm. Knobs and
left/right key (+,-) can also be used.
If GAIN is set to be relevant with REF(MLC mode), then smaller the REF,
higher the receiving sensitivity, and weaker the anti-interference ability.
In circumstance where the curve is well within the screen, yet the
background noise is high and the shape of the signal is obviously abnormal,
it's possible that the receiver is jammed by a strong interference. Moreover,
the interference could be outside the spectrum and thus cannot be directly
observed on the screen. To cope with it, continue raising the REF or set it to
ALC. On the other hand, manually increase attenuation (ATT) or reduce gain
(AMP) would help. These settings are all included in LEV menu.
(9) Set SPAN appropriately by pressing SPAN button. The narrower the
width, the higher the resolution, the lower the background noise, and slightly
better the anti-interference ability. Vice versa. With other demands satisfied,