Glossary
Glossary- 4 CSA7000 Series, TDS7000 Series, & TDS6000 Series Instruments User Manual
dB
Decibel: a method of expressing power or voltage ratios. The decibel scale is
logarithmic. It is often used to express the efficiency 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:
dB =20 logᏋVi
VlᏐfor optical, dB =10 logᏋPo
Pi Ꮠ
where Viis the voltage of the incident pulse, Vlis the voltage reflected back
by the load, Pois the power out, Piis the power in, and log is the decimal-
based logarithmic function. See Optical Bandwidth on page 3--68.
dBm
A logarithmic measure of power referenced to 1 milliwatt (1 mW optical
power = 0.0 dBm):
dBm =10 log Ꮛoptical power
1mW Ꮠ
DC coupling
A mode that passes both AC and DC signal components to the circuit.
Available for both the trigger system and the vertical system.
Delay measurement
A measurement of the time between the middle reference crossings of two
different waveforms.
Delay time
The time between the trigger event and the acquisition of post trigger data.
Digitizing
The process of converting a continuous analog signal such as a waveform to a
set of discrete numbers representing the amplitude of the signal at specific
points in time. Digitizing is composed of two steps: sampling and quantizing.