Which M Ode To Use - Tektronix 2205 Operator's Manual

Which M ode to Use

P-P AUTO/TV LINE—With this mode set, the range of the LEVEL
control is confined to the values between the triggering-signal
peaks. For example, selecting P-P AUTO and rotating the
LEVEL control to the center of its range establishes a trigger
point about midway between the peaks of the triggering signal.
In this mode, the absence of a triggering signal causes the
sweep to free-run. And with signals below 20 Hz, the P-P AUTO
circuit may not find the correct level.
Whenever TRIGGER SOURCE is set to VERT MODE, the trigger­
ing signal is supplied by the channel being displayed - or as
shown in Table 2 -1 .
The P-P AUTO mode is effective for monitoring logic signals and
television lines having at least 20 Hz repetition rate.
fJ-P AUTO at the instrument front panel also sets the TV LINE
triggering mode.
NORM - This mode produces a sweep only when the triggering
signal meets the criteria set by the LEVEL and SLOPE controls.
With NORM mode selected, range of the LEVEL control is suffi­
cient to set any voltage threshold that can be displayed by the
instrument. In the absence of a triggering signal, no sweep
occurs.
Use the NORM mode for viewing infrequent events and erratic
signals.
SGL SWP - When this mode is selected, the sweep is triggered
only once. Press the RESET button once to arm the trigger cir­
cuit and illuminate the READY indicator.
occurs, the sweep runs once and the READY light extinguishes.
Use the SGL SWP mode to display or photograph nonrepetitive
or unstable signals.
TV FIELD - This mode triggers the sweep at the beginning of a
television field.
must interrupt the trigger signal by setting the input coupling
switch momentarily to GND then back either DC or AC until the
desired field is displayed.
2205.Operator' s
To change the TV field being displayed, you
Operation
Selecting
When a trigger event
2-11