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Acquiring Waveforms
3-68
CSA7000 Series, TDS7000 Series, & TDS6000 Series Instruments User Manual
Figure 3- 20: Vertical setup menu with optical controls
First select Ch1 in the Waveform section of the menu. Then touch the Wave-
length button that matches your system.
You select the mask, bandwidth, and Bessel-Thompson filter appropriate for
your optical standard using the Masks menus. If the Bessel-Thompson filter is
on, the instrument is a reference receiver. For detailed information on using
masks, see the CSA7000, TDS7000 & TDS6000 Series Option SM Serial Mask
Testing and Option ST Serial Triggering User Manual.
Optical Bandwidth
CSA7000 Series: Traditionally bandwidth is defined as the frequency at which
the power out is one half the power out at a frequency near DC. In the voltage
domain the power dissipated into a resistive load (such as a 50 Ω termination of
an input) is the V
RMS
2
/R where V
RMS
is the RMS of the voltage swing seen at
the resistive load, and R is the resistance value. A logarithmic scale using
decibels is typically used to describe the frequency dependent response. A value
expressed in terms of a decibel relative to a reference is defined as:
dB = 10 log
Ꮛ
value
reference
Ꮠ