Page 410 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition
P. 410
propagation distance and the penetration depth into the medium being insonified. The higher the frequency, the lesser the penetration into the medium, allowing for a more detailed surface paint of the target for target shape and texture classification.
For small-item surface discrimination, the wavelength of the pulse must be no larger than the target—and much shorter for any detailed imaging of the target. For better small-object discrimination, the higher the frequency the better. What suffers at very high frequencies
FIGURE 15.14
Destructive no sound
P1
Constructive max sound
d = λ/2 P2
Constructive max sound
Destructive no sound
15.1 Sonar basics 403
Constructive dipole projection of sound along a beam axis.
Table 15.3 Some Advantages and Disadvantages of ROV-Mounted Single and Multibeam Sonar Systems
Sonar System Advantages Disadvantages
Single beam Multibeam
• Able to view 360 around vehicle
• Up to 10 frames per second image update rate at short range
• Slow image generation
• ROV-mounted projector allows narrow reception beam width
• Higher computing power needed drives cost upward
