Garmin GPSMAP 235 Sounder - Manual (Page 45)

Sounder Setup Page (con’t.)
• Noise Rejection: Removes cross talk from other sounders or ignition noise from poor
boat motor installations (non-shielded plugs, etc.).
There are three options:
• Off: The unit will not remove anything it thinks is cross talk noise. The noise will
be displayed on the screen.
• On: The unit will always remove anything it thinks is cross talk noise, and attempt
to ‘repair’ the damage done by suspected interference with real echoes.
• Auto: Auto is the default setting. Auto identifies the presence of cross talk noise,
and turns the rejection on when it needs to. When the noise disappears, it turns the
rejection off.
To set Noise Rejection:
1. Highlight the ‘Noise Rejection’ field and press T . A submenu will appear.
2. Select the Noise Rejection setting and press T .
• Keel Offset: Allows you to set the point from which the sounder will measure depth.
Keel offset makes it possible to measure depth from the bottom of your keel instead of
from the transducer's location. A positive number will measure depth from a deeper
point while a negative number reflects a shallower point.
To set Keel Offset:
1. Highlight the ‘Keel Offset’ field and press T . Use the R to enter the keel
offset value and press T .
• Frequency: Allows you to select a transducer frequency. Frequency refers to the
“pitch” of the sound that the transducer sends and receives. Typically, low frequencies
(50 kHz) provide the deepest readings. High frequencies (200 kHz) provide better res-
olution and detail. The dual frequency modes of the GPSMAP 235 combine low-and
high-frequency operation which gives you the advantages of both.
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SOUNDER PAGE
Noise Rejection and Keel
Offset Setup
A. Auto is the noise rejection default setting. Auto
identifies the presence of cross talk noise and
turns the noise rejection on when it needs to.
When the noise dissapears, turns the rejection
off.
B. Keel offset allows you to precisely set the point
from which the sounder will measure depth.
A B
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