Verifying that the bottom is correctly detected
Locating the bottom (seafloor) is important for the ME70 system. The ME70 needs this bottom lock to locate the correct depth, and to stay on it during the operation, even if the depth changes continuously. Occasionally, difficult environmental, water or bottom conditions may inhibit a bottom lock.
Context
The Bottom Detection parameters provide separate limits for minimum and maximum depth. These limits may be used to obtain a bottom lock on the depth when the ME70 is transmitting. The Bottom Backstep parameter allows you to manually modify where on the bottom echo the depth will be detected.
Tip
If you have problems with bottom detection, you may consider disabling it. This can be useful if you only wish to study targets in the water column.
Procedure
1 Open the Active menu.
2 Select Bottom Detection.
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3 Set Minimum Depth and Maximum Depth to values fit for the depth at your current location.
•  The Minimum Depth setting eliminates all unwanted bottom detections from the transducer face and down to the depth you have chosen.
•  Set the Maximum Depth to approximately 50 % more than the expected depth.
If you set maximum depth to a value identical or smaller than the minimum value, the bottom detection algorithm will be disabled. The ME70 will not detect the bottom at all, and the displayed depth will be 0.00 m.
Tip
If you have problems with bottom detection, you may consider disabling it. This can be useful if you only wish to study targets in the water column.
4 Select OK to save the selected settings and close the dialog box.
Result
If the ME70 should loose bottom detection due to air or other disturbances, it will try to relocate the depth within the minimum and maximum depths you have defined.