Common Mode
A circumstance where a signal is induced in phase on both sides of a
differential network.
dB
Decibel: a method of expressing power or voltage ratios. The decibel scale is
logarithmic. It is often used to express the ef
fi
ciency of power distribution
systems when the ratio consists of the energy put into the system divided by
the energy delivered (or in some cases, lost) by the system. One milliwatt of
optical power is usually the optical reference for 0 dBm. The formula for
decibels is:
where V
i
is the voltage of the incident pulse, V
l
is the voltage re
fl
ected
back by the load, P
o
is the power out, and P
i
is the power in. (See page 21,
Electrical versus Optical Bandwidth
dBm
A logarithmic measure of power referenced to 1 milliwatt (1 mW optical
power = 0.0 dBm).
Degradation
A deterioration in a signal or system.
Differential Mode
A method of signal transmission where the true signal and its logical
compliment are transmitted over a pair of conductors.
Digital signal
A signal made up of a series of on and off pulses.
Digital transmission system
A transmission system where information is transmitted in a series of on
and off pulses.
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80C12B Optical Sampling Module User Manual