Humminbird HELIX 9 Operation Manual page 48

Adjust the Sensitivity
Sensitivity controls how much detail is shown on the display and will adjust the sensitivity of all sonar frequencies. To eliminate the
clutter from the display that is sometimes present in murky or muddy water, decrease the sensitivity. When operating in very clear
water or greater depths, increase the sensitivity to see weaker returns.
Adjust the Sensitivity for all Sonar Frequencies
Use the following instructions to adjust the sensitivity for all sonar frequencies.
1. Sonar X-Press Menu: With a Sonar View displayed on-screen, press the MENU key once.
2. Select Sensitivity.
3. Press the RIGHT or LEFT Cursor keys to increase or decrease the sensitivity.
Adjust Beam Sensitivity
Your control head model may allow you to adjust the sensitivity of individual frequencies. The available frequencies are determined
by your control head model and the installed transducer. Use the following instructions to adjust a single beam.
1. Main Menu (Advanced User Mode): Press the MENU key twice. Select the Sonar tab.
2. Select 83 kHz Sensitivity or 455 kHz Sensitivity.
HELIX CHIRP GPS: Select Medium Sensitivity Offset or High (455 kHz) Sensitivity Offset (HELIX CHIRP DI GPS only).
3. Press the RIGHT or LEFT Cursor keys to increase or decrease the sensitivity.
For example, in the illustration shown below, the sensitivity of the 83 kHz beam in the Split Sonar View can be adjusted without
affecting the sensitivity of the 200 kHz sonar returns. For more information about this view, see Compare Sonar Beams.
frequency
Sonar (2D)
Increasing the Sensitivity of the 83 kHz Beam (83 kHz/200 kHz)
83 kHZ
lower range
200 kHZ
frequency
48
upper range
lower range