6-30
The horizontal sweep frequency of the scope should always be kept lower than, or equal to, the
waveform frequency; it should never be higher. If the sweep frequency were higher, only a portion of the
waveform would be presented on the screen.
If, for example, three cycles of the waveform were to be displayed on the screen, the sweep
frequency would be set to one-third the frequency of the input signal. If the input frequency were 12,000
hertz, the sweep frequency would be set at 4,000 hertz for a three-cycle scope presentation. For two
cycles, the sweep frequency would be set at 6,000 hertz. If a single cycle were desired, the setting would
be the same as the input frequency, 12,000 hertz.
DUAL-TRACE OPERATION
The information presented in the previous sections served as a general overview of basic single-trace
oscilloscope operation using one channel and operating controls. Now, you will be introduced to DUAL-
TRACE operation.
Dual-trace operation allows you to view two independent signal sources as a dual display on a single
CRT. This operation allows an accurate means of making amplitude, phase, time displacement, or
frequency comparisons and measurements between two signals.
A dual-trace oscilloscope should not be confused with a dual-beam oscilloscope. Dual-beam
oscilloscopes produce two separate electron beams on a single scope, which can be individually or jointly
controlled. Dual-trace refers to a single beam in a CRT that is shared by two channels.
Q-17. Scopes that produce two channels on a single CRT with a single beam are referred to as what
types of scopes?
Components Used to Select Vertical-Deflection Operating Mode
The VERT MODE controls (figure 6-34) allow you to select the operating mode of the scope for
vertical deflection.
