![](/images/new-backgrounds/1255746/25574633x1.webp)
1.10 Erasing Weak Echoes
Dirty water or reflections from plankton may be painted on the display in green or light- blue. These weak echoes may be erased as follows:
1.Press the SIG LEV key. The following display appears.
| SIGNAL LEVEL |
| SIGNAL LEVEL | ||||
| ▲ OFF |
| ▲ OFF | ||||
|
| SL1 |
|
| SL1 | ||
|
| SL2 |
|
| ▼ | SL2 |
|
|
| SL3 |
|
| SL3 |
| |
|
| SL4 |
|
|
|
| |
|
|
| (At | ||||
|
| SL5 |
| ||||
|
|
|
|
|
| ||
| ▼ SL6 |
|
|
|
| ||
|
|
|
|
|
|
|
|
(At |
|
|
|
Figure 1-21 Signal level display
2.Press the SIG LEV key again to select sig- nal level (echo color) to erase. The color deleted disappears from the color bar and is replaced with
Weak echoes
Signal level adjusted
Figure 1-22 How SIG LEV works
1.11 Measuring Depth
The VRM (Variable Range Marker) functions to measure the depth to fish schools, etc.
1.Press the [▲] or [▼] key to place the VRM on an echo.
2.Read the VRM range just above the VRM.
200k
0.0 0
VRM (green) | 20 |
39.8
40
60
49.6![](/images/new-backgrounds/1255746/25574633xi5.webp)
![](/images/new-backgrounds/1255746/25574633xi6.webp)
![](/images/new-backgrounds/1255746/25574633xi7.webp)
![](/images/new-backgrounds/1255746/25574633xi8.webp)
![](/images/new-backgrounds/1255746/25574633xi9.webp)
![](/images/new-backgrounds/1255746/25574633xi10.webp)
![](/images/new-backgrounds/1255746/25574633xi11.webp)
![](/images/new-backgrounds/1255746/25574633xi12.webp)
![](/images/new-backgrounds/1255746/25574633xi13.webp)
![](/images/new-backgrounds/1255746/25574633xi14.webp)
80![](/images/new-backgrounds/1255746/25574633xi16.webp)
![](/images/new-backgrounds/1255746/25574633xi17.webp)
Figure 1-23 How to measure depth
with the VRM
9