Page 366 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

358 CHAPTER 13 Communications
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Power in watts (log scale)
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Fiber-optic power conversion (dB to watts)
FIGURE 13.32
Fiber-optic power conversion chart.
5. Any amplifier should increase the power level (positive dB gain). 6. Referenceof10dB510X
7. Referenceof3dB52X
8. Referenceof0dB51X
9. Referenceof210dB50.1X 13.2.8 Baseband transmission
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Baseband transmission is described as the raw electrical signal transmission typically surrounding some zero value. A signal is considered “baseband” when it includes frequencies at or near 0 Hz up to the highest frequency in the signal. For instance, a baseband digital transmission signal emanates a series of 0s and 1s from a PC to some other device. For an analog device, such as a telephone, human voice impresses an alternating current over a conductor of a phone line to transmit sound to the receiver. Baseband signals can be distance limited; therefore, some type of modulation scheme is necessary in order to condition the signal for long-distance transmission. The physical device used for modulating and demodulating a carrier signal is typically colocated on to the same device called a modem (or modulator/demodulator).
13.2.9 Modulation
IEEE defines modulation as “a process whereby certain characteristics of a wave, often called the carrier, are varied or selected in accordance with a modulating function.” Modulation is the process
Power in dBm
Power in dBμ