Diver6 User Manual
Section 2: Page 13 of 87
Expected Range
The expected range of the Diver6 System will be dependent upon the conditions of deployment. Extensive
range testing of the Diver6 System has demonstrated the following ranges:
1.
Over 1,000 m in “ideal” conditions
2.
Over 800 m in a marina environment
Limitations on Range
The effect of thermoclines
One of the environmental constraints of acoustic diver tracking is the interference of thermoclines. A
thermocline typically happens in calm waters where a layer of warmer water is sitting on top of a layer of
colder water (Figure 2).
The interface between the
warmer water and the
colder water can (in certain
circumstances)
cause
significant
acoustic
interference and restrict
the range of the Diver6
System.
If the diver is below the
thermocline
and
the
Topside Modem is above
the thermocline, part of the
acoustic signal between the
two can be bounced off the
thermocline. This effect is
known as an acoustic mirror.
An acoustic signal that approaches the thermocline will partially travel through the thermocline with the
balance of the acoustic signal being reflected. The signal is therefore dependent upon environmental
conditions.
Thermoclines can significantly reduce the effective range of the Diver6 System: physical ranges in severe
thermoclines have been reduced to about 60m. The best mitigation for this effect is to either lower the
Topside Modem below the thermocline, or reduce the range between the Topside Modem and the diver.
If both the diver and the Topside Modem are on one side of the thermocline, the acoustic signal path will
be better and possibly behave much in the same way as an unobstructed signal path. If either the Diver
Modem or the Topside Modem is in the thermocline, then the acoustic signal can be absorbed within the
thermocline.
Figure 2: Thermocline Diagram
