Tektronix TDS1000B Series Operator's Manual page 22

1
Introduction to Oscilloscopes and Probes
In analog oscilloscopes, the CRT limits the range of sine
wave frequencies that the oscilloscope can display. At low
frequencies, the signal appears as a bright, slow-moving dot
that does not display the waveform. When signal
frequencies exceed the display speed of the CRT, the
displayed signal is distorted, attenuated, or both.
You can use an analog oscilloscope to display rapidly
varying signals in real time. The phosphor-based display of
an analog oscilloscope has an intensity grading feature,
which makes the trace appear brighter where the signal
features occur most frequently. You can then distinguish
between signal details by observing the intensity levels of
the displayed waveform.
1-8 TDS1000B and TDS2000B Series Oscilloscopes – Operator Training Kit