491 Echo Sounder Operations Manual
Page 69
Manual controls
Gain
0 to 75 db
Clutter
0 to 9
Signal level
0 to 5
Noise limiter
ON/OFF
White level
Any single color
Other
Screen color palette
Depth marker
Position marker
Zoom in/out
Shift
Ranges
15, 30, 60, 120, 200, 400, 800, 1000, 2400 feet
5, 10, 20, 40, 80, 150, 300, 500, 800 meters
Advance
speed
1/8 to 2/1
Depth units
Feet, meters, fathoms
Installation
calibrations
Include speed, temperature, gain, and transducer
type
Table 4: 491 echo sounder features (Continued)