- The CRO display is simply a Cathode Ray Tube
within which electrons are deflected to "trace"
the input signal(s) in a visible form.
- The display is shown above and has nine divisions
on both the X and Y axes. These divisions are used to
measure the amplitude of the signal ( In volts ) on the
Y-axis and the Period of the signal ( In seconds ) on the
- The Red line on the diagram on the left
represent the most useful site to set the zero
axis of the horizontal trace ( this applies when
the input signal is zero volts ). This is because
this site allows a signal to be viewed on the
largest scale possible ( This increases
measurement accuracy ).
- The Red line is situated in the middle of
the display which is most useful if the
measurement being made is of an A.C. signal as we
require the signal to be visible on both sides of
the zero axis. It is also useful if we are unsure
of the type of signal which we are measuring.
- The example on the left is an A.C. signal
that does not have a zero voltage axis in the
center of the display which leaves us with a
reduced viewing area. This does not allow us to
make the most accurate measurement possible
to CRO Features
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Revised: 15 September 2004