Page 404 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

15.1.9 Sonar equations
Sonar equations look at signal losses compared to signal sources to determine the likelihood of detection of the sound source. For the passive sonar, only one-way sound transmission and noise levels are considered in deriving the minimum detection threshold, whereas on active sonar systems the sound must travel first from the sound source (the transducer of the active sonar system) through the water column to the target and then (after the backscatter) back to the receiver (Figure 15.9).
The passive sonar equation:
DT
Passive sonar
SL SL TL NL DI DT
SLTLNL1DI$DT
15.1 Sonar basics 397
Sonar equipment
DI
NL
FIGURE 15.9
DT
DI
SL
Active sonar
Sonar equipment
NL
SL 2TL TS NL DI DT
TS
Sonar equations for (a) passive and (b) active sonar.
TL
2TL