Page 202 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

FIGURE 8.40
Instrument 1 Instrument 2
Instrument 8
RS232 RS232
RS232
Analog input 1 Analog input 2
Analog input 16
8.5 COTS underwater connectors 191
DC power supply
RS232 RS422
Modem
Modem
DC power supply
If no internal battery
Computer
LinkQuest acoustic modem connection diagram.
Acoustic modems
(Courtesy LinkQuest.)
Acoustic modems (Figure 8.40) are commercially available from several vendors, providing reliable and long-range data rates up to 38.4 kb/s. Characterization of the water path is needed for higher data rates. Changing environmental conditions may also affect data rates.
Radio frequency
WFS Technologies has demonstrated RF systems (Figure 8.41) that provide data rates of up to10 Mb/s at very close ranges (12 m), decreasing to 10 bps at longer ranges. Longer ranges are possible in fresh water or through a ground path. An air path is also possible under site- specific conditions. Unlike acoustical and optical communications, transmission through water is not affected by bubbles, thermal stratification, ambient noise, or turbidity.
Connectorless power transfer
An inductive recharge system (Figure 8.42) developed by Florida Atlantic University (FAU) is up to 88% efficient, operating at 4.25 kHz. The unit can transfer up to 1000 W, 070 V, 030 A.