Figure 9.3: The noise test display
Common sources of underwater noise include passing boats, snapping shrimp and other biological
noise, intensive rain or the sound of nearby breaking surface. By default, PILOT will simply adjust its
sensitivity ‘to deal’ with whatever noise might be present. However, you can also conduct a noise
test to find what noise is there, and then set the surface station detection threshold manually (the
mobile station will always auto-adjust, as there is no link to control it manually during an operation).
While you can do without a noise test, doing one and then setting the detection threshold is a
prudent step just to be aware of the noise on the site, and estimate the impact in terms of tracking
range reduction that it might have on your operations today.
But, be aware! Once you set the detection threshold, you have overridden the system’s auto adjust
and it will maintain your setting until you switch the system off and on again. So, if noise levels
should rise (and they DO frequently grow and then recede again underwater), you must adjust the
threshold again. Noise test and threshold adjust is a very simple procedure. Here is how it’s done:
1.
Insure that the surface transducers are the water and select Noise Test from the Action
menu.
2.
Press the Start Test button.
