Tektronix 222 Operator's Manual page 93

Section 6-222 DSO Operators
SECTION 6
MORE ON HOW IT WORKS
The detailed explanations contained in this section are for reference
when the user requires more information on certain controls and
features. The reference paragraphs are indicated in Tables 3-1,3-2,
and 3-3, the Operator's Quick Reference tables.
6.1 AUTO SETUP
The VOLTSIDIV, SECIDIV, and Vertical POSITION controls are set to
provide the user with a quick setup for viewing the waveform when
AUTO SETUP is used. Autoranging takes place on a priority basis,
with channel 1 having the number one priority when signals are
applied to both channel probes. If a signal is applied to only one
probe, autoranging for VOLTSIDIV, SECIDIV, Trigger LEVEL, and
vertical position occurs on that signal, and the channel without a
signal applied is turned off (except channel 1 will not be turned off if
neither channel has a signal applied). When a signal is applied to
both channels, the channel 1 signal determines the SECIDIV setting
and Trigger LEVEL; both signals are autoranged bertically and
positioned within the crt display area. The channel 1 signal is
positioned in the top half of the graticule area, and the channel 2
signal is positioned in the bottom half. The Vertical input coupling is
set to ON, and the trigger level is set for triggering on the signal. See
Table 6-1 for a list of all the default settings that occur when an auto
setup is done.
Auto Setup will not set the SECIDIV setting into the SCAN or ROLL
ranges (0.1 sec per division and slower). The practical lower
frequency limit is about 20 Hz. Signals having a too low frequency or
repetition rate, will not be auto ranged correctly. Signals of too high a
frequency will be autoranged vertically but will require further setting
of the SECIDIV control to produce a usable display of the signal's
wave shape.