Kongsberg 1007D, Operator'S Manual

Page: 43 / 49

1007D Altimeter Operators Manual 974-72007001/1.0
Tips for Successful Altimetry Page 37
Kongsberg Mesotech Ltd.
Port Coquitlam, BC - Canada
Cause Possible Solution
The acoustic returns from the
sea-bottom or target are too
narrow or weak. Decrease the minimum threshold and/or the
minimum return width and/or increase the TVG
gain offset. For long ranges a longer transmit
pulse length may be required. Target strength
will depend on its shape, size, composition, &
texture, as well as its location & orientation
with respect to the altimeter's beam. If
necessary, re-orient the altimeter to minimize
the acoustic grazing angle to the target/bottom.
Acoustic noise or spurious
additional targets are being
detected outside the range
window. This may be seen as erratic altitude
measurements due to noise, mid-water targets,
or multipath interference. These can be filtered
out by judicious adjustment of the
minimum ,
maximum range , increasing the minimum
threshold , and decreasing the TVG gain offset .
Select the " peak return " decision method for
bottom tracking applications.
If necessary, re-orient or relocate the altimeter
away from nearby objects.
Large discontinuities in the
bottom.
Increase the range window to accommodate
anticipated gradients
.
Multipath interference Reduce the altimeter ping rate to reduce the
effect of multipath. Select the "
first return "
decision method for bottom tracking
applications.
No echoes received due to air-
bubbles on transducer face. Keep transducer face clean and free of air
bubbles. If necessary, use a mild detergent.